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Let Me Be a Pony
August 24th, 2015, 12:16 PM
Thread ain't fully complete.
This thread will cover: Depth of field, aperture, shutter speed, ISO settings, focal lengths, focus point, crop sensors, angle of view, angles, types of shots, types of lenses, positive and negative space, distortions, size within the frame, camera movement, dolly shots, panning and more.
An important thing to know is that this thread is severely based on DSLR cameras, for now.

Source(from post 1 and 3) - http://www.cambridgeincolour.com/tutorials/wide-angle-lenses.htm http://www.digitalcameraworld.com/2012/05/16/apertures-photography-cheat-sheet-when-to-go-small-and-when-to-go-wide/ http://www.nikonusa.com/en/Learn-And-Explore/Article/g3cu6o2o/understanding-focal-length.html http://www.steves-digicams.com/knowledge-center/point-of-focus-and-depth-of-field.html#b https://photographylife.com/what-is-crop-factor http://www.imaging-resource.com/news/2015/03/31/what-do-telephoto-lenses-really-do https://en.wikipedia.org/wiki/Ultra_wide_angle_lens https://en.wikipedia.org/wiki/Wide-angle_lens http://www.slrlounge.com/school/cropped-sensor-vs-full-frame-sensor-tips-in-2/


This thread will start out with the simple parts of photography and it will build up daily with even more information. Photography is highly connected with cinematography, this is why I'm starting off with this.


Depth of field


The wider the aperture, the faster the shutter speed. The narrower the aperture is, the slower the shutter speed can be.
The only difference between the flowers below is the aperture.

http://i.imgur.com/ymDpkgz.jpg?1

On the image on the left, the aperture is F25. On the right, the aperture is F5.6.
F5.6 is a larger aperture (opening), thus it lets in more light quicker (causing a shorter shutter speed), and it gives a shallower depth of field. Shallow depth of field places more of the areas outside the point of focus into blur.

The depth of field is controlled by the following factors:

• Focal length
• The distance of the objects(As you get closer to your subject , the lesser the depth of field is).
• Aperture - F- number
• Focus point

Focal length

The Focal Length is not:

• The length of the lens.
• Half the length of the lens.
• The diameter of the lens.

Focal length is the measurement(in millimeters) from the optical center of the lens to the camera's sensor.

The optical center is also known as the focal point.
For all lenses(including primes) the focal length changes depending on what the lens is focussing on.
For example, a 50mm lens when focusing to infinity will have a focal length of 50mm, but when focusing on an object 1 meter away the focal length needs to be moved 2.6mm further away from the camera sensor in order for the image to be in focus. Thus what you thought was a 50mm image is actually a 52mm image.

The focal length tells us the angle of view—how much of the scene will be captured—and the magnification—how large individual elements will be.

- The longer the focal length, the narrower the angle of view and the higher the magnification. The shorter the focal length, the wider the angle of view and the lower the magnification.

- Focal length is not a measurement of the actual length of a lens, but a calculation of an optical distance from the point where light rays converge to form a sharp image of an object to the digital sensor or 35mm film at the focal plane in the camera.

- You can change the depth of field using a different focal length. For example, so-called "long" lenses (telephoto ) - from 80 mm to 600 mm take pictures with a shallower depth of field.
A wide-angle lens - 35 mm takes shots with a far greater depth of field.

- The longer the focal length, the narrower the angle of view and the higher the magnification. The shorter the focal length, the wider the angle of view and the lower the magnification.

Focal length is not a measurement of the actual length of a lens, but a calculation of an optical distance from the point where light rays converge to form a sharp image of an object to the digital sensor or 35mm film at the focal plane in the camera.
Technically speaking, the focal length of a lens is the distance between the lens and the back of the camera, where the image is formed. For example, in a 55mm lens, there are 55 millimeters between the lens and the camera’s image sensor.
There are also 55 millimeters between the lens and the spot where light focuses in front of the camera. This works in a similar way to the way that your eyes work. Try this: place your hand a foot away from your face and focus on it with your eyes until it looks crystal clear. Now, slowly move your hand towards your face. Keep trying to focus on your hand as you move it.
No matter how hard you try to keep your hand in focus, at a certain distance you just won’t be able to do it anymore. When this happens, you have passed the focal point of your eyes. Most human eyes focus at or near 50 millimeters, so that means that the focal point of your eyes is 50 millimeters away from your face.


Wide lenses with a very short focal distance bend light much stronger than ordinary lenses, bringing objects to a focus in a shorter distance. Additionally, the shorter the focal length of the lens, the shorter the distance needed to obtain the same FOV(field of view) compared to a longer focal length lens.
This is the main reason why the ultra-wide lenses take everything into focus.
http://i.imgur.com/M5vsShm.png
Diagram of how the light is bent when it's faced against a short focal length and a long focal length.

The lower the focal length, the wider the field of view is.

It's also important to note that short focal lengths increase the depth of field.
Longer focal lengths got a more shallow depth of field. Already forgot if I even mentioned this before.

Aperture – F – number

What is an F-stop?
F- stop is the ability of a lens to collect light, depending on the aperture and focal length.

Wider apertures (smaller F numbers) provide limited depth of field and vice versa - small apertures (Higher F numbers) increase the range of the sharp focus .
Narrow apertures can have a far slower shutter speed than wider apertures.
Wider apertures can have a much faster shutter.

http://i.imgur.com/kajsFxd.jpg
The picture above summarizes the basics you'd need to know about apertures. More things connected with apertures will be covered below.


Shutter speed + Aperture

In photography, shutter speed or exposure time is the length of time when the film or digital sensor inside the camera is exposed to light, also when a camera's shutter is open when taking a photography.
The amount of light that reaches the film or image sensor is proportional to the exposure time.

http://i.imgur.com/ykkEJZW.jpg

Let's say we want to take a picture using the first example aperture f/11 and shutter speed 1/15.
If you stop your aperture at f/8 , it will let in half the amount of light from f/11 , so you have to double the amount of shutter speed to 1/30.

Opening up a lens by one stop allows twice as much light to fall on the film in a given period of time. Therefore, to have the same exposure at this larger aperture as at the previous aperture, the shutter would be opened for half as long (i.e., twice the speed, faster).
If you want to skip setting the shutter speed to match the aperture,
you can always use Aperture Priority mode.



http://i.imgur.com/UZn4HMS.jpg

The picture above was shot with a shutter speed of 1/8 seconds. The movement and the object are blurred.
Something interesting to note is that if you shoot an object that moves from one side of the frame to the other, it will come out more blurred and it will have blurry outlines when moving. The opposite could be said when shooting a subject that is approaching or moving away from you.
Also, the closer the object is, the more effective the shot will be at a slower speed.


What is aperture priority?


Aperture priority, often abbreviated A or Av (for aperture value) on a camera mode dial, is a setting on some cameras that allows the user to choose a specific aperture value while the camera selects a shutter speed to match, thereby ensuring proper exposure.
Remember the diagram above, the one with the shutter speed and aperture connection? This is where this might come in handy. Aperture priority does this automatically for you.

What is a focus point?

When a photographer uses the term "point of focus", he is referring to that object in a photograph at which he wants to draw the most attention.
"Focus" itself refers to the amount of the image that is sharp. Both the point of focus and the amount of focus affect the resulting image. In short, altering each one changes the look of the final photograph.

http://i.imgur.com/ru9EbAs.jpg

In these two images, the point of focus was the same, the coneflower. However, the amount of the photo in focus, or the amount of sharpness, also called "depth of field", is different.


Further explanation on the point of focus:

Every photograph has a specific location at which the photographer wants the viewer's eye to rest. Seen through the lens of the camera, this can be a single point or multiple points. In upper-end digital cameras, photographers have the option to choose between the number of these points and their location.

http://i.imgur.com/BK73Qgv.jpg

In these first two examples, there is only one focal point(point of focus), as indicated by the red square in each. However, the location of the red square is altered compared to the first photo. As you can readily see, this greatly modified the look of the photo. One is visually more pleasing than the other.


Here is an important tip: If your camera doesn't allow you to move your point of focus from within the lens, you can still do so. Press your shutter button halfway to lock the focus on your chosen focal point, and then physically shift your camera to arrange for the composition you desire. Be careful though not to alter the distance from your lens to your focal point, as this will disrupt the overall sharpness of the image.

In the flower photos above, the photographer’s choice of a focal point was simple. He wanted to feature the forward flower.
However, what point would you choose for a wide-angle scene? In these situations, when you desire to show the general appearance of a location, it often works best to set your camera to use a wider focus range, it sampling from multiple points. In some cameras, this is called "dynamic range" focus.

In the photo below, there are ten separate squares. The camera sampled from each of these areas to give the image the largest amount of sharpness. The photographer also used a smaller aperture to enable more of the objects in the image to be in focus.

http://i.imgur.com/mhqZSlN.jpg


Film speed (ISO)

Generally you want to keep film speed low. High film speeds cause a grainy look with film and a "noisy" look with digital - both cause many small specks to appear as part of the image and most people don't find the affect pleasing (some people do like film grain but it's generally agreed that digital "noise" does not look good). The main reason to ever increase film speed is to compensate for a low light situation and allow you to use a shutter speed and/or aperture that you could not otherwise use. Increasing the film speed is similar to increasing the amount of light, although you are not really increasing the light, you are just making the film or digital sensor more sensitive to it.
The point is that by increasing film speed by one stop, you can then use a faster shutter speed or make the aperture one stop smaller and still have the same overall exposure level.


Types of lenses

Zoom lenses

Zoom lenses have a zoom ring so you can change the focal length.

What are the advantages of using a zoom lens?

-The most obvious reason for buying zoom lenses is their versatility. Zoom lenses can be great when a photographer needs to be sure he can handle a variety of different situations – you can go from wide-angle to telephoto in a quick turn of the zoom ring without the need to physically move. Landscape and wildlife photographers, for example, are often limited to a particular spot or area, so being able to zoom to an area of interest can be invaluable for properly framing a shot.

-Image stabilization. Modern zoom lenses often offer 3-4 stop image stabilization systems, be it Canon’s Image Stabilization (IS), Nikon’s Vibration Reduction (VR), Sigma’s Optical Stabilization (OS) or Tamron’s Vibration Compensation (VC). Even if you have an f/4 lens you can still get sharp images when shooting non-moving subjects in dark environments. Thanks to the image stabilization technology, your lens will make some of its internal optical elements move and shift to counter camera shake, which lets you use extremely slow shutter speeds.
Image stabilization is not just limited to zoom lenses. Some of the newer fixed focal length lenses also boast image stabilizer technologies, such as the newly announced Canon 35mm f/2 IS. Lastly, do keep in mind that image stabilization can be present on lenses or camera bodies. Sony and Pentax DSLRs, for example, have sensor-based image stabilization, which will work with pretty much any mounted lens.

-Portability. A single zoom lens can replace two or three prime lenses. This also means that you only need to worry about moving around with a single attached lens. A single zoom lens might save you from carrying a large backpack. In a way, certain zoom lenses allow you to reduce weight, because you don’t need to bring several primes to cover the whole range. Less lens swapping also means cleaner sensor and optical elements.

Prime lenses

Prime lenses has a fixed focal length, so it can't zoom in or out. Buy the lens that matches the focal length you like best. When you compose your shots, you have to physically move closer or farther away.
Prime lenses are much cheaper than zoom lenses, because of their simple structure.

What are the advantages of using a prime lens?

-To get higher quality images. Because prime lenses aren’t built to zoom, they have a much simpler design. This leads to fewer visual defects and aberrations. In short, you get a much less distorted and more technically correct image when you shoot with a prime lens.

-To get a better aperture at a lower cost. Wide apertures (low F-numbers) have their cost, especially when you add them to zoom lenses. Have you ever seen a giant zoom lens sports photographers use a 500mm lens and wondered why it needs to be so big? The reason is the aperture. To get the lens to zoom with a big aperture, you need a much bigger lens. Making the lens really really big also makes it really really expensive. That’s why they cost so much too.

Prime lenses are great for scenes that have low light, because of their wide aperture.

Ultra wide angle lenses. F <21mm
Wider lenses tend to magnify distance between objects while allowing greater depth of field.
Ultra wide angle lenses(including wide angle lenses) are good for making close up objects look huge so we can see a lot of their details while making far away objects look very far away.
You see, the shorter the focal length, the larger the distance is between the objects.

Here's an example of this:

https://upload.wikimedia.org/wikipedia/commons/e/e5/Focal_length.jpg
F - 18mm, the blue bottle looks as if it's far away from the red one, although it's not.

Keep in mind that there is a distortion(this may depend if your lens is curvilinear or rectilinear) in ultra wide angle lenses(including wide angle lenses). The distortion is called "barrel distortion".
I'll make a new post about the types of distortions later on, but I'll explain what a barrel distortion is in short.
A barrel distortion is when the lines are curved towards the edges of the frame. Look at the picture of the red and blue bottle. Notice how the red bottle is curved a little when being shot at a 18mm? You can also see a small curve on the 34mm shot. There are no curves on the 55mm shot, because 55mm lenses are "normal lenses". Imma cover what those are further below, after I cover wide angle lenses.
You can be creative with a barrel distortion. A distortion doesn't always mean it's bad.
Barrel distortion lenses, they're mostly used for special effects in photos.

There are 2 types of (ultra)wide angle lenses.
First one is Rectilinear. They don't have barrel distortion.
Second is Curvilinear(Also known as a fisheye lens). These do have barrel distortion. If you want to limit the barrel distortion, you can always increase the focal length to include less of it.

Wide angle lenses F = 21-35 mm
Wide angle lenses are quite similar to ultra wide angle lenses. Everything I said about ultra-wide angle lenses applies for wide angle lenses.
They are a great option if you want to include details of both the foreground and the background.
Wide lenses(including ultra-wide) with a very small focal length bend light more strongly than ordinary lenses which puts everything that your camera sees into focus very quickly.

Kit lenses (normal lenses). F = 35mm-70mm

This category includes the so-called "normal" lenses not that the others are abnormal. These lenses are suitable for street photography, but also for documentary. The lenses that come with your camera (often called "kit lenses") usually have the parameters of 18-55 or 18-70 mm and do a great job for beginners.

While telephoto lenses flatten the perspective and wide angle lenses stretch it, 50 millimeter lenses show the spatial location almost exactly as it is visible to the human eye.
Unlike superzoom lenses where the difference in perspective is large, at a 50 millimeter lens will find very little difference between what you see through the viewfinder directly. Just the optical zoom without distortion, the perspective and angle of view are the reasons these lenses are called "normal".

Near-telephoto lenses F = 60-70mm

Near-telephoto runs from 35 to 50mm for cropped-frame cameras. Full frame cameras have a near-telephoto range of approximately 60–70mm. Also known as medium telephoto.
I'll explain in another post what a cropped-frame camera is, alongside a full frame camera.

Telephoto lenses F = 135mm-300mm


Telephoto is considered proper telephoto. Typical telephoto focal lengths are from 70–200mm for cropped-frame and 135–300mm for full-frame cameras.

Zoom lenses are the most popular DSLR lenses at present and come in a range of configurations and levels of quality. Obviously the benefit of zooms are that you do not need to physically get closer to your subject to get a tighter framing of the image. These lenses can have quite narrow ranges or quite long ones.

Keep in mind that if you buy one with a long focal length (for examples you can get them in lengths ranging up to 300mm or longer) that the longer your focal length the more impact that camera shake has on your images. More and more lenses these days are being released with Image Stabilisation (IS) to combat camera shake.

The main use of a telephoto lens is NOT to “bring things close.” In fact, professionals often use their long lenses when they could easily get much closer to their subjects and use a different lens. Yes, telephoto lenses do appear to bring things close, but that’s the blunt end of the instrument.

The two most common uses of a telephoto lens by a professional photographer would be:

To put backgrounds out of focus.
To change the perspective of the picture.

http://i.imgur.com/Yn5Kwop.jpg

Amateurs always think that long lenses are for “bringing things close”, but putting a background out-of-focus is a much more common use for a long lens in a professional’s hands.

Here’s how to use a telephoto lens to put a background out-of-focus:

The out-of-focus effect of f2.8 on a background is much greater with a 200mm lens then with a 50mm lens. So if you wanted to dramatically put a background out-of-focus, and you had the choice, it would be best to use a 200mm lens. And the tighter you get on the subject—just head and shoulders, for example—the more pronounced the effect.

So if you wanted to do everything you could to put a background out-of-focus for a head shot you would:

-Use your largest aperture. That’s the smallest number.
-Use the longest lens you have.
-Get as close as you can to your subject to fill the frame.
The closer you get, the more out-of-focus the background.

Here’s how to change the perspective of a picture with a telephoto lens:

-Position your subject against the background and then use the longest lens you have to compose the picture.
-This time you need to carefully consider your f-stop. Using a large aperture (small number) may actually put the background out of focus too much. And using a smaller aperture may force you to use a shutter speed that will be difficult to hand hold without camera shake. Turning up your ISO or using a tripod would both be ways to prevent camera shake.

Let Me Be a Pony
August 24th, 2015, 03:20 PM
Admins/mods, the reason I'm making a new post rather than editing the prior post is because I can only have no more than 10 images in a single post.

Will be continuing with the type of shots.

Source: http://www.thewildclassroom.com/wildfilmschool/gettingstarted/camerashots.html https://www.youtube.com/watch?v=K6N2SpA2XPI

Type of shots

Full shot

http://i.imgur.com/1HygsbM.jpg

A full shot is great for providing context, as well as orienting your audience geographically
within your world.
A Full Shot allows more than one character to be in the frame at the same time, and it’s wide
enough to allow your characters to use body language to express themselves.

Full Medium shot

http://i.imgur.com/wXCI0DB.jpg

This shot is similar to the Full Shot, but instead of cropping below the feet, we are making our first cut just below the subject’s knees.

Medium shot(cowboy shot)

http://i.imgur.com/BlGGArp.png

Enough space is left just below of the waist of the subject, so if they drop their hands, their wrists will not be cut off from the bottom wall of the shot.
This shot is helpful for people who need quick access to holsters/pockets.
This shot is equally important for subjects who wish to put their hands down to their sides.

Medium close-up

http://i.imgur.com/uEvgsa7.png

From the waist up.
A medium close up is great when you want to include even less environment, and gain more insight into the emotional state of the character.
Small emotional nuisances may start to register within this image size.
This shot is still wide enough to fit multiple elements within the frame.
This shot allows you to multitask the character's emotional state with their body language, whilst at the same time giving you the opportunity to include other characters, props or surroundings.

Close shot

http://i.imgur.com/WIXFUQN.png

From the chest upwards.
One of the first shots which usually focusses on the emotional world of the character.
The head of the character must be slightly below the top frame of the composition.
The actor’s face is the main tool used to convey information when you are this close.
As we continue to move even closer to the actor, his body can still communicate expressiveness, but the actor's face(specifically the eyes) start to become the centrepiece for these shots.

Wide close-up


http://i.imgur.com/XyUJ4RB.png

From the shoulders upwards.
Close-Up shots are used to gain access into the inner world of the character.
The top part of the frame usually rides just above the top of your character’s head.

Full close-up

http://i.imgur.com/3oXG9VM.png


This shot may become awkward if we begin to lose the subject’s eyes or chin.
The eyes, they must be above the top two thirds of the frame(Rule of thirds is next on my list, since it has a lot to do with framing shots properly).
You don’t want to clip the subject’s chin with the bottom frame of the composition.
A little bit of the top head of the character is allowed be cut off. In this shot, a little bit of the shoulders were included.

Medium close-up

http://i.imgur.com/RJrCHj6.png

We are starting to lose even more of the top of the head.
The chin is also getting dangerously close to the bottom of the frame.
Plus of the shot: It allows you to dig even deeper under the character’s skin, to see
what is beneath the words they are saying.

Extreme close-up

http://i.imgur.com/sxv16TP.png

An extreme close-up shot goes a step further.
We allow the chin to dip itself into the bottom frame.
In this shot, the bottom wall is framed just below the subject's lips.
This is as close as we can get into the inner world of a character, before moving into macro close-ups.

Edit: Adding macro close-ups now.

Macro close-up

http://i.imgur.com/ZNIXVno.png

Macro close-ups allow us to feature a particular part of the body, for example a wrist watch as we see in this case.
Macro close ups should help progress your narrative and not be used as a "filler", for instance a character walking down a desolate highway at night by themselves. The film maker in this case may decide to shoot a macro close up of the character's ear to help punctuate the sight. By shooting a macro close up of the ear when the scene is quiet for example, we increase the detail for a viewer.

Most common mistakes when framing shots:

-Too much room above the head, which creates dead space.
-Too little room above the head. In some shots, clipping the top of the head is a mistake, unless we are taking the subject into close-up shots or even further This is not advisable for full and medium shots.
-Cutting off the joints of the limbs.

There are more shots that I'll talk about later on, shots connected with angles and such.

Next post will be connected with the rule of thirds.
After that, I'll cover the camera sensors and crop factors.

Let Me Be a Pony
August 25th, 2015, 04:11 AM
Rule of thirds.

The rule of thirds involves mentally dividing up your image using 2 horizontal lines and 2 vertical lines, as shown below. You then position the important elements in your scene along those lines, or at the points where they meet.

http://i.imgur.com/qMRNrcH.png
Important elements (the shed, and the border between the ground and the trees) are positioned along the lines and at the intersections.

The idea is that an off-centre composition is more pleasing to the eye and looks more natural than one where the subject is placed right in the middle of the frame. It also encourages you to make creative use of negative space.

What is positive and negative space?

Positive space is that, which usually takes the eye of the viewer. Negative space is that, which doesn't attract much attention.

Negative and positive space can work in both ways. For example, look at the image below.

http://i.imgur.com/LIUu54N.png

What took your attention at first? When you first took a look of the picture, did the buildings take your eyes first, or was it the key?
That which has taken your attention is considered as positive space. The opposite is for negative space.

Another picture of positive and negative space:

http://i.imgur.com/hyK8BWW.png?1

The plum line’s positive space is intersecting within the negative space(The negative space in this picture is obviously the black background).

Who gave birth to the rule of thirds?

Painters. It has existed centuries before photography.
If I remember correctly, an early Renaissance Italian painter and architect called "Giotto" first used this.
Famous Renaissance painters, such as Leonardo Da Vinci, Michelangelo, Caravaggio and others helped popularize it.
PS, photography is highly connected with painting in a way. A lot of general photography knowledge has been given to us by painters.

Sensor size

Let’s think of a pocket camera. Have you ever noticed that when you shoot with such a camera you almost never get a shallow depth of field and everything is sharp in focus? That's because the sensor of the pocket cameras is so small. But if we take a look at cameras with bigger sensors, for example full frame cameras or with a crop factor of 1.5/1.6, you will see that the depth of field is more shallow.
To summarize, a bigger sensor size allows you to achieve a shallower depth-of-field.

http://i.imgur.com/GCo95ov.png

Generally, a full frame sensor can provide a broader dynamic range and better low light/high ISO performance yielding a higher quality image than a crop sensor. Full frame sensors are also preferred when it comes to architectural photography due to having a wider angle which is useful with tilt/shift lenses.
On the other side, while a crop sensor DSLR doesn’t provide the same level of image quality as a full frame DSLR, it does offers major advantages when it comes to cost. It can also be very effective for telephoto photography for the extra reach gained from the crop sensor multiplier. For example, this can be very useful when shooting, wildlife and other types of photojournalism. Just imagine that on a Canon crop frame body such as a Canon 7D; your Canon 70-200mm f/2.8 lens is effectively a 112-320mm lens!

What do crop sensors do exactly?

When making pictures with a crop sensor, the field of view that you lose in the shorter focal lengths is quite big – have a look at the photos below for comparison.

http://i.imgur.com/H9iCNhz.png

As you can see, the size of the sensor and its crop factor(I'll elaborate further on the crop factor further below) can have a drastic effect on the equivalent focal length of a lens. A 200mm lens on a small sensor with a 2.7x multiplication factor (Nikon’s CX cameras) produces an equivalent focal length of 540mm.

The focal length of a lens is the physical property of a lens and it never changes irrespective of the camera sensor.

Sadly, this is where things can get confusing for many photographers.
The focal length of a lens is the physical property of a lens and it never changes irrespective of the camera sensor. So when you look at the above table, always keep in mind that the smaller sensor is not magically transforming your lens into a longer lens - it is just cropping a lot of the image, as shown in the below illustration:

http://i.imgur.com/LoKgfU3.png
Full-Frame vs APS-C vs M43 vs CX

Digital cameras have complicated things somewhat. Film has been replaced by sensors which are usually smaller than 35mm film.
Because they're physically smaller, they capture a smaller area of the projected image, resulting in a photo which covers a narrower angle of view.
Putting a lens meant for a full frame camera onto a body with a crop sensor produces the crop factor.

Today, when evaluating DSLR lenses, you will often come across lenses that are made specifically for crop sensor cameras. Since these lenses have a smaller image circle, they will either not work at all on full-frame cameras, or will work (provided that they have the same lens mount, as shown below), but display very dark corners, as shown below:

http://i.imgur.com/XCw9cpi.png

How do I find out if my camera has a crop sensor?

Look at the kit lens that came with your camera.
Crop sensors are designed to work with your camera body by providing a smaller lens projection; their focal lengths will be shorter than a full frame camera – staring at 18mm, rather than 24mm.

There will also be your camera brand’s marking to indicate which body it was made for.

Here are the most popular brands, designed for crop sensors:

Canon — EF-S
Nikon — DX
Sony — DT
Pentax — DA
Sigma — DC
Tamron — Di-II

If you decide to upgrade to a full frame camera, these lenses will no longer work on your Full Frame body, unless you use an extension for the crop Size lenses; buy carefully.
Extensions may make it possible for crop lenses to work on full frame bodies, but there are drawbacks to that.
One of the main drawbacks is that there will be severe vignetting when taking shots.

http://i.imgur.com/z91PbwP.png?1

Another drawback is that you won’t be able to take images of objects that are far away, although you gain a closer macro.

50mm is a great focal length when you’re using a full frame camera but that’s not so good on a crop sensor because it’s unnaturally "zoomed". If you’re a Nikon user and want to buy a f/1.8 lens, It would always be recommend to buy the 35mm over the 50mm for a much more natural appearance.

How do I find out the angle of view i’m getting?

You have to know what your crop factor is. After you know your camera’s crop factor, multiply that crop factor to the millimeters of your lens.

A Canon crop sensor has a 1.6x crop factor which causes a 28mm lens to have the same angle of view as a 45mm lens would on a 35mm film camera or full-frame DSLR.
Multiply 1.6 with 28. You get the angle of view of a 44.8 mm lens.

If you multiply a lens's focal length by the camera's crop factor, you get the "equivalent focal length", which is the focal length needed to produce the same angle of view on a 35mm camera. This is why you might also hear crop factor referred to as the "focal length multiplier" (or "FLM").

http://i.imgur.com/CfpamXu.png
Here's another table to help you understand this.
The top green side defines the crop factor.
The left green side defines the millimeters of a lens.

Pluses of full frame sensors.

-Shallower depth of field.
You may have noticed that although your point-and-shoot camera has an f/1.8 lens, it is nearly impossible to accomplish short depth-of-field on most point-and-shoots. The reason is that the sensor size affects apparent depth-of-field. Since a 35mm equivalent (full frame) sensor is larger, it can accomplish more shallow apparent depth of field than an APS-C sized (crop sensor) camera.

-Provides a broader point of view.

-Better low/high ISO performance.
Digital imaging sensors have tiny little light sensors that record light and produce a pixel. The tiny sensors are called photosites. Naturally, the larger the photosite, the more ability it has to capture weak light signals. Picture it like a satellite dish. Therefore, when all other factors are equal, a full frame sensor will always perform with less noise at high ISOs than “crop frame” DSLR cameras.

-Viewfinder brightness.
Because full frame cameras use larger lenses, they can produce a brighter viewfinder image. Very handy.

-Higher image quality than a crop sensor.

Pluses of crop sensors.

-Effective for telephoto photography, for the extra reach gained from the crop sensor multiplier.

-Lighter.
A crop sensor Canon 18-200mm weights in at 595g vs a full frame super-zoom Canon 28-300mm at 1670g.
If you read anything of what I read on this post, you can understand why i'm comparing a 18-200mm lens on a crop sensor camera to a 28-300mm lens with a full frame sensor camera.
The crop factor gives you a range advantage over a full frame coverage.
100mm will appear as if shot with a 160mm lens on an APS-C DSLR.
The sensor itself barely adds any weight to the DSLR, but the full frame sensor requires larger, heavier, and more expensive lenses. This means that the gear can be much more cumbersome and awkward to use.

-Cheaper.

-Easier to auto-focus.
It’s easier to auto-focus on an APS-C DSLR because the focus points are more spread out compared to a full frame DSLR.

-Broader depth of field.
Depth-of-Field advantage using a crop sensor camera (macro or landscape) because you are further away from the subject. You simply get a broader depth-of field using an APS-C DSLR.
Full frame users will argue that you can’t get nice bokeh on a crop sensor camera body.

Let Me Be a Pony
August 26th, 2015, 02:34 AM
Source: http://www.britannica.com/art/motion-picture/Expressive-elements-of-motion-pictures#ref508579 https://en.wikipedia.org/wiki/Panning_(camera) http://www.mediacollege.com/video/shots/dolly.html http://www.elementsofcinema.com/cinematography/camera-moves.html http://www.videomaker.com/article/14221-camera-movement-techniques-tilt-pan-zoom-pedestal-dolly-and-truck https://en.wikipedia.org/wiki/High-angle_shot http://www.mediaknowall.com/camangles.html https://newasthodgson.wordpress.com/2015/04/21/camera-shots-angles-and-movements/ http://www.videoeditingsage.com/camera-angles-objective-and-subjective.html http://www.mediacollege.com/video/shots/over-shoulder.html https://en.wikipedia.org/wiki/Over_the_shoulder_shot

Movement shots

Tilting

Moving the cameras lens up or down while keeping its horizontal axis constant. Nod your head up and down - this is tilting.

29D-IgQDIHU
Example of a tilt shot.

Panning shot(Panorama shot)


One of the simplest and most common movements is to turn, or pan (from the word panorama), the camera horizontally so that it sweeps around the scene. It can also be tilted up or down in a vertical panning shot or in a diagonal pan, as when it follows an actor up a stairway.

Tracking, dollying, and tracking can even be combined with panning in a complex movement that may require the adjustment of focus or aperture. One such camera movement that is often used imitates the gaze of a traveler who turns in a moving automobile or train to focus on a stationary point of interest.
Very rapid camera movements may express a sudden surge of emotion or a contemplated action

xD0HoBxDaAg
Example of a pan shot.

To create a smooth pan it's a good idea to practice the movement first. If you need to move or stretch your body during the move, it helps to position yourself so you end up in the more comfortable position. In other words you should become more comfortable as the move progresses rather than less comfortable.

Achieving a smooth pan in photography:

When photographing a moving subject, the panning technique is achieved by keeping the subject in the same position of the frame for the duration of the exposure.
The length of the exposure must be long enough to allow the background to blur due to the movement of the camera as the photographer follows the subject in the viewfinder.

The exact length of exposure required will depend on the speed at which the subject is moving, the focal length of the lens and the distance from the subject and background. An F1 car speeding along a straight might allow the photographer to achieve a blurred background at 1/250th of a second, while the photographer might need to go as slow as 1/40th to achieve the same amount of blur for a picture of a running man.

http://i.imgur.com/tB1J83X.jpg

Dolly shot

When the entire camera is moved forward or backward, this move is called dolly. If the camera is on tripod, the tripod will also be moved.
Dollies are often used when recording a subject that moves away or toward the camera, in which case the goal would probably be keeping the subject at the same distance from the camera. For an optimal dolly, the camera should be mounted on a wheeled-platform, such as an actual dolly, or a shopping cart, depending on the budget. Moving the camera forward is called dolly in. Moving the camera backward is called dolly out.

d1W2_WoA04I
Example of a dolly shot.


What is the difference between zooming and dollying, besides the fact that zooming requires the camera operator to be in a static position?
A zoom shot is a magnification of the image, whereas when you’re actually dollying, you’re moving through space - You displace objects and you give the audience a much more three dimensional field on this two dimensional surface we are viewing.

Dolly counter zoom

A dolly counter zoom(also known as the Vertigo shot) is a rare type of shot of great stylistic effect. To accomplish it, the camera must dolly closer or further away from the subject while the zoom is adjusted so the subject’s size remains the same. Notably, Hitchcock’s Vertigo (1958), Spielberg’s Jaws (1975), and Scorsese’s Goodgellas (1990) used dolly counter zoom to demonstrate a character’s uneasiness.


As you pull the dolly out, you have to zoom in at the same time, trying to match the speed of the zoom with the speed of the dolly.
Now if you want the opposite effect, you got to dolly in from here while zooming out. Either way, most like to start with the dolly all the way in to get an idea of what zoom they want to start with or end with.

Getting this effect takes a lot of practice to get just right, as the speed which you need to dolly will change depending on where you are in the focal length range. Just keep doing the shot over and over again until you get it right – just know that it takes a bit of time.

LutRaK8YmA0
Example of a dolly counter zoom.

Tracking shot

Tracking is similar to dollying. The main difference being that in dollies the camera is moved towards or away from the subject, whereas in a tracking shot, the camera is moved sideways, parallel to an object, keeping track of the object.

s_HuFuKiq8U
Example of a tracking shot.

Camera Angles

Bird's-eye view

http://i.imgur.com/dtePUmO.png

This shows a scene from directly overhead. Familiar objects viewed from this angle might seem totally unrecognisable at first. This shot does, however, put the audience in a godlike position, looking down on the action. People can be made to look insignificant, ant-like, part of a wider scheme of things. Hitchcock (and his admirers, like Brian de Palma) is fond of this style of shot.

High angle shot

http://i.imgur.com/sxjbUup.png

Not so extreme as a bird's eye view. The camera is elevated above the action using a crane to give a general overview. High angles make the character seem smaller, and less significant (or scary).
The object or character often get swallowed up by their setting - they become part of a wider picture.

Eye level shot

http://i.imgur.com/VM9QdI1.png

A fairly neutral shot; the camera is positioned as though it is a human actually observing a scene, so that the actor's heads are on a level with the focus. The camera will be placed approximately five to six feet from the ground.
It's like the viewer is standing alongside the subject but still sees exactly what the subject sees.

When using this camera angle the other actors in the scene may look directly into the camera to create the illusion that the audience is now the character.
When used in this way, the camera angle still remains objective, since the viewer is still an unseen observer in the scene but he is close enough to the subject that he is seeing exactly what the subject is seeing.

This shot is also used in interviews.

Over the shoulder shot(OSS)


http://i.imgur.com/E4vJFvq.jpg

This shot is framed from behind a person who is looking at the subject. The person facing the subject should usually occupy about 1/3 of the frame.
OSS helps to establish the position of each person, and get the feel of looking at one person from the other's point of view.

This type of shot is very common when two characters are having a discussion and will usually follow an establishing shot which helps the audience place the characters in their setting.

If in our first scene the camera is over the right shoulder of our character, then in the next scene the camera has to be over the left shoulder of our other character and vice-versa. This rule is extremely important.

Low angle shot

http://i.imgur.com/5D3iolu.jpg

These increase height (useful for short actors like Tom Cruise or James McAvoy) and give a sense of speeded motion. Low angles help give a sense of confusion to a viewer, of powerlessness within the action of a scene. The background of a low angle shot will tend to be just sky or ceiling, the lack of detail about the setting adding to the disorientation of the viewer. The added height of the object may make it inspire fear and insecurity in the viewer, who is psychologically dominated by the figure on the screen.

Dutch shot(canted angle)

Sometimes the camera is tilted (ie is not placed horizontal to floor level), to suggest imbalance, transition and instability (very popular in horror movies). This technique is used to suggest POINT-OF-View shots (ie when the camera becomes the 'eyes' of one particular character,seeing what they see — a hand held camera is often used for this.

Dutch shots can sometimes give the feeling of movements.

http://i.imgur.com/up1MrHJ.png
Example of how a dutch shot can be used to give out the effect of movement. Photo by VT user goodnightxmoonx

Tomorrow I'll continue with the size within the frame, light painting and types of distortions.

wolf g
August 26th, 2015, 08:50 AM
thank you for informations

lightPainting
August 28th, 2015, 05:42 PM
WOW..............................................nice job...*clapping*

ImCoolBeans
August 29th, 2015, 10:24 PM
This is awesome, really great thread with great information!

Let Me Be a Pony
August 30th, 2015, 01:11 AM
This post is connected with distortions.
Source: https://photographylife.com/what-is-distortion https://en.wikipedia.org/wiki/Distortion_(optics) http://photo.net/beginner-photography-questions-forum/00THUb http://digital-photography-school.com/why-are-my-buildings-falling-over-a-short-guide-to-perspective-distortion-and-correction-in-photography/ https://en.wikipedia.org/wiki/Chromatic_aberration http://digital-photography-school.com/chromatic-aberration-what-is-it-and-how-to-avoid-it/ https://photographylife.com/what-is-chromatic-aberration


Types of optical distortions

Barrel distortion

When straight lines are curved inwards in a shape of a barrel, this type of aberration is called “barrel distortion”. Commonly seen on wide angle lenses, barrel distortion happens because the field of view of the lens is much wider than the size of the image sensor and hence it needs to be “squeezed” to fit. As a result, straight lines are visibly curved inwards, especially towards the extreme edges of the frame. Here is an example of strong barrel distortion:

http://i.imgur.com/XkKVIBX.png

Note that the lines appear straight at the very center of the frame and only start bending away from the center. That’s because the image is the same in the optical axis (i.e. the center of the lens), but its magnification decreases towards the corners.

Barrel distortion is typically present on most wide angle prime lenses and many zoom lenses with relatively short focal lengths. The amount of distortion can vary, depending on camera to subject distance. Even standard 50mm prime lenses can potentially yield barrel distortion at close distances. Barrel distortion can be decreased significantly by using compensating optical elements, but completely eliminating such distortion is nearly impossible. Some lenses like Nikon 14-24mm f/2.8G have a number of such distortion compensating elements, which heavily increase both the weight and the size of the lens. This is why wide-angle lenses are typically bigger and heavier than standard / normal lenses.

Fisheye lenses, which take hemispherical views, utilize this type of distortion as a way to map an infinitely wide object plane into a finite image area.
In a zoom lens, barrel distortion appears in the middle of the lens's focal length range and is worst at the wide-angle end of the range.

You can easily fix barrel distortion in photos with Photoshop(though the format of the picture is recommended to be RAW).

How can you dodge barrel distortion?

By using rectilinear lenses. I've written the difference between rectilinear and curvilinear lenses in my first post.

Again, rectilinear lenses stretch out the image, henceforth the reason why they do not have barrel distortion.
They yield straight lines without bending them (resembling human vision).

Curvilinear lenses(fisheye lenses), they do not stretch the image, but they can achieve barrel distortion, depending on the focal length.

http://i.imgur.com/gOE3QNw.png

Rectilinear and curvilinear lens verbiage is typically applied only to wide angle lenses.

Pincushion distortion

Pincushion distortion is the exact opposite of barrel distortion – straight lines are curved outwards from the center. This type of distortion is commonly seen on telephoto lenses, and it occurs due to image magnification increasing towards the edges of the frame from the optical axis.
This time, the field of view is smaller than the size of the image sensor and it thus needs to be “stretched” to fit. As a result, straight lines appear to be pulled upwards in the corners, as seen below:

http://i.imgur.com/vy9M2Wp.png

Pincushion distortion is also a very common aberration(distortion), especially on zoom lenses. Expensive super telephoto prime lenses have compensating elements that can significantly reduce pincushion distortion to negligible levels, but most consumer and even pro-level zoom lenses like
Nikon 80-400mm VR suffer from pincushion distortion. In fact, pincushion distortion can be very heavy on consumer-grade lenses, something that you will quickly notice in images.

It is important to note that most zoom lenses that go from wide angle to standard or telephoto focal lengths typically suffer from barrel distortion at the shortest focal lengths, which gradually transitions to pincushion distortion towards the longest end. A good example of such behavior is the Nikon 18-300mm VR, which starts out with strong barrel distortion at 18mm, then quickly switches to pincushion distortion at 28mm and stays that way till 300mm.

Mustache distortion

A mixture of both types, sometimes referred to as mustache distortion (moustache distortion) or complex distortion, is less common but not rare.

Straight lines appear curved inwards towards the center of the frame, then curve outwards at the extreme corners, as shown below:

http://i.imgur.com/vZ3mxa6.png

This is the reason why mustache distortion is often referred to as “complex” distortion, because its characteristics are indeed complex and can be quite painful to deal with. While this type of distortion can be potentially fixed, it often requires specialized software. You cannot just use the built-in tools in Lightroom and Photoshop, unless a specific lens profile is already built to combat such distortion. If you attempt to deal with such distortion as barrel-type, you will end up curving the extreme corners a lot more. And if you attempt to compensate for pincushion distortion, you will end up curving it for even stronger barrel distortion towards the center.

Perspective distortion

Another distortion type that is often seen in images is perspective distortion. Unlike optical distortion, it has nothing to do with lens optics and thus, it is not a lens error.
When projecting three dimensional space into a two dimensional image, if the subject is too close to the camera, it can appear disproportionately large or distorted when compared to the objects in the background.
This is a very normal occurrence and something you can easily see with your own eyes. If you take a smaller object like your mobile phone, then bring it very close to your eyes, it will appear large relative to say your big screen TV in the background (and the farther your phone is from your TV, the smaller the TV will appear relative to your phone). The same thing can happen when photographing any subject, including people.

For example, if you photograph a person with an ultra wide angle lens up close, their nose, eyes and lips can appear unrealistically large, while their ears can look extremely small or even completely disappear from the image.

http://i.imgur.com/YhbG1yN.png
NIKON D700 + 24-70mm f/2.8 @ 27mm, ISO 200, 1/250, f/8.0

Look at the size of his head – it appears disproportionately large relative to his body. His eyes, nose and lips are very much enlarged, while his ears are dwarfed. You can imagine what it would look like if I got closer to his face or used a wider lens at a shorter distance.

You might hear some photographers say that one should use longer focal lengths to photograph people, or they will get distorted due to the lens’ short focal length. This is a mostly false statement, because
lenses have no perspective. Other than fisheye lenses, all lenses have the same perspective – it is the camera to subject distance that determines perspective, not the focal length. There is an illusion of different perspective of lenses, because with long focal lengths you have to stand further away from the subject to frame them the same way. If you were to stand at the same distance, the subject would appear exactly the same! So if you take a 50mm lens and an 85mm lens, there is no difference in perspective between the two, as long as you stand in the same spot and keep the subject to camera distance the same. Yes, the subject would certainly appear smaller with the 50mm lens due to shorter focal length / wider field of view, but the perspective and proportions would be the same on both. So the point of longer focal length lenses in such cases, is the possibility to enlarge the subject in the frame, while keeping normal perspective. Telephoto lenses do not magically fix perspective distortion – they force you to move back from the subject, which is what changes the perspective.

http://i.imgur.com/rbznGol.jpg
NIKON D3S + 14-24mm f/2.8 @ 14mm, ISO 200, 1/125, f/8.0

The car looks completely distorted, because the photographer stood very close to it and photographed it with a wide-angle lens (Nikon 14-24mm). Note that the left part of the car looks disproportionately big – even the left light looks about 50% bigger than the one on the right, although you know that they are both the same in size.
The car is occupying the majority of the frame and everything in the background looks relatively small. If the photographer used a normal lens and stood in the same spot, he would have ended up with only a part of the car filling the whole frame. Yet, if he were to crop both images for the same field of view by heavily cropping the wide angle shot, the perspective distortion effect would be the same on both.

Perspective distortion is caused only by distance, and has nothing to do with focal length or sensor size by itself.

The viewing angle only seems to be related because people often fill the frame with the subject, which puts them much closer with a wide angle lens than a telephoto lens.

How much perspective distortion is too much is a matter of opinion that will vary from person to person, but a rough range would be from 2 to 4 meters. Too close tends to make noses look big, and too far tends to make ears look like they stick out.

Chromatic aberration

Chromatic aberration (also known as color fringing or dispersion) is a common problem in lenses which occurs when colors are incorrectly refracted (bent) by the lens, resulting in a mismatch at the focal point where the colors do not combine as they should.

A function of light conditions or using a lens incorrectly, chromatic aberration can ruin a photograph and reduce the amount of detail captured by the camera. While lenses and cameras are developed with technology to reduce these glitches, the simple fact of the matter is they still pop up under the right (or wrong?) conditions.

http://i.imgur.com/pGOafcl.png

The image above is a good example of chromatic aberration. Parts of the image appear soft, which could be partly from the lens being slightly out of focus, except that the aberration is almost certainly causing a loss of detail resolution. Notice the blue halo on the left hand side of the image and scattered throughout in various areas.

http://i.imgur.com/KQEcZ7B.png

Lenses can change the speed light moves through it, and this is a function the frequency of that light. As the light travels through the lens, the different wavelengths (colors) move at different speeds and fall in different places on the sensor. Sometimes using a lens in a way it was not designed can cause an aberration—like this shot, using a lens that was possibly inappropriate at such an extreme close-up. As a result, the red, green, and blue converge on different points and create image channels that don’t line up.

Why does chromatic aberration occur?

Chromatic aberration happens because your lens acts as a prism; bending light depending on the various properties of the glass, and much like the triangle-shaped one made famous by Pink Floyd, colors passing through it are split at different angles.

How to avoid chromatic aberration?

http://i.imgur.com/WJrx8T3.jpg

-Avoid high contrast scenes.
Chromatic aberrations tend to flare up in high contrast scenes. Particularly guilty are shots against white backdrops, landscape shots against a bright sunrise, or, as in the example of this Cheetah, where the light source is behind the subject.

This means that sometimes there’s nothing to do except try and reframe your shot. Swap your backdrop out to something which better matches your subject’s primary color, or wait for more favorable lighting conditions. If you absolutely must capture this shot as-is, then swap over to RAW and get your fingers ready for the possibility that you may need to do some touch-ups in post-production.

-Check your focal lengths.
Although it’s nice to have access to a wide range of focal lengths, the fact is that most zoom lenses will exhibit various aberrations at the shorter and longest extremes of their focal range. So being able to choose a different focal length will usually help to remove the issue of visible chromatic aberration.

Likewise, using a zoom lens at a wide angle will usually introduce not just chromatic aberrations but various other defects in your image. Instead, consider choosing a prime wide angle lens to handle the job, or, perhaps more practical for your case, make a panorama at a focal length that does not exhibit the chromatic aberration issue and then join the photos in post-production for a flawless result.

-Stop down your aperture.
Chromatic Aberration can be dramatically reduced by stopping down the lens(using a smaller aperture). Although this will depend on the exact type of lens you are using, stopping down your aperture will usually help to play down the noticeable effects of most lens defects, including chromatic aberrations. Remember that you may need to consider dropping the shutter speed or boosting the ISO to compensate for the light loss if working in a non-studio setting. Red, Green, Blue or a combination of these colors can appear around objects. Fast aperture prime lenses are typically much more prone to chromatic aberration than slower lenses.

If you have access to lighting or flashes, then be sure to experiment with the effect of boosting and adding in extra light.

-Reframe your subject to the centre of the frame.
Chromatic aberrations tend to occur more frequently as you move further away from the center of the frame. This is generally as a result of the curvature of the lenses within the barrel. Therefore, being able to reframe your subject closer to the middle may help to reduce, or even completely eliminate, issues with chromatic aberration and other lens-based defects.
This means that you may need to crop your image after shooting to achieve the desired frame, which may be an issue if you absolutely have to maintain every pixel in your photo.

You can always use Photoshop and other image editing post-production programs to remove the chromatic aberration, but it's much more convenient to not have the hassle to do all that in the first place.

goodnightxmoonx
August 30th, 2015, 05:03 PM
This is so informative!! Thank you for using my photo in the dutch shot explanation!

Let Me Be a Pony
December 5th, 2015, 07:52 AM
So much shit to correct... I'll edit the prior posts whenever I got free time. Gotta add more information and to correct some parts from prior posts.

Source from this post:

http://www.digitalcameraworld.com/2015/11/13/how-and-when-to-use-nd-filters-and-what-the-numbers-mean-2/
http://www.cambridgeincolour.com/tutorials/neutral-density-filters.htm
https://luminous-landscape.com/understanding-graduated-neutral-density-filters/
http://www.cambridgeincolour.com/tutorials/polarizing-filters.htm

Filters

Neutral Density(ND) Filters.

Neutral density (ND) filters reduce the amount of light entering the camera, enabling a longer exposure time than otherwise possible. This can emphasize motion, or make an otherwise tumultuous scene appear surreal and quiescent. Alternatively, an ND filter also enables larger apertures, which can produce a shallower depth of field, or achieve a sharper photo.
ND filters give you the flexibility to set the aperture and shutter speed you want, rather than what the conditions dictate.

An ND filter can be used on a sunny day to slow things enough to create a sense of movement, but they’re even more effective around dawn or dusk, when they can turn an already-slow exposure into one several seconds long, enabling you, for example, to turn a surging tide into a gentle mist.

ND filters aren’t just for blurring the elements – you can use them to make moving people disappear. You’ll need a really long exposure of several minutes, but people walking through a scene will simply vanish – architecture photographers use this trick when shooting crowded tourist hotspots.
And it’s not just slower shutter speeds that can be obtained by using ND filters. If you’re shooting portraits on a bright, sunny day, for example, you may find you can’t shoot at wide apertures to obtain a shallow depth of field because it requires a shutter speed that exceeds the fastest available.
Adding an ND filter will enable you to select a wider aperture.

An ND filter is nothing more than a semi-transparent piece of glass that gets placed in front of your lens. What makes it special, however, is that it obstructs a precisely controlled fraction of incoming light, and does so uniformly — thereby not altering image contrast or sharpness. The obstruction also aims to be equal across the visible spectrum, thereby not introducing a color cast (although this isn't always the case). This last characteristic also happens to be why it's called a neutral density filter.

http://i.imgur.com/hwSWlgg.jpg
Basically, when you're browsing filters, the filter has a number(ND6 for example). That number implies how many F stops the filter reduces.
The table above explains more on this subject.

Common uses of ND filters:

• Modest increases in exposure time, such as with waterfalls.
• Extreme increases in exposure time,such as blurring in broad daylight.
• Shallower depth of field. Although ND filters are primarily used to achieve longer exposures, a less common application is to enable a shallower depth of field in very bright light. For example, most SLR cameras have a maximum shutter speed of 1/4000 second, so a subject in direct sunlight might therefore require an f-stop greater than about f/4.0 (at ISO100). With a 2-stop ND filter, one could reduce this to F/2.0 — yielding a dramatic improvement in background blur and subject isolation.

One can often instead adjust the aperture, ISO or shutter speed by one stop without substantially changing the image.

Longer exposure times can achieve a wide variety of artistic effects, including softening the appearance of turbulent water, blurring waves of blowing grass, or emphasizing motion within a crowd of people.
However, let's focus on a specific waterfall example. Without a filter, one would use both the smallest aperture and the lowest ISO speed available.
With a waterfall under soft daylight, F/22 and ISO100 might yield an exposure of 1/10 second. Unfortunately, not only is this duration insufficient, but the f-stop also had to be increased to the point of reducing sharpness due to diffraction.
Using an ND filter allows you to address both of these problems, but the extent to which either is improved depends on how you choose to allocate its effect. With a 5-stop ND filter, the same settings would yield a 32X longer exposure time — giving the water a much silkier appearance. Alternatively, one might feel that a 16X (4-stop) exposure time increase is sufficient when weighed against the potential for having a sharper photo, and could instead also decrease the f-stop to F/16.

http://i.imgur.com/poENpiS.jpg
F/22, ISO100, exposure of 1/10 seconds.

http://i.imgur.com/Ku6ndVo.jpg
F/16, ISO100, exposure of 2 seconds.

Graduated Neutral Density Filters

Graduated ND filters(sometimes also referred to as split neutral density filters) are clear on the bottom and slightly opaque on the top, with either an abrupt or a gradual shift in the middle. They are used to darken the brighter part of a scene so that it falls within the dynamic range of the camera.

In the examples below,the same scene has been photographed three times, whilst a different graduated filter is being held each time. In each case, the transition line between light and dark has been placed over the horizon.

http://i.imgur.com/PXMcWfq.png

You can see in each image that the sky around the filter is virtually pure white, but that part visible through it has retained detail.
Filters are available in a number of strengths, usually given in ‘stops’. One stop is a halving of the light coming through the opaque part of the filter. So a one stop filter will darken the bright area by a factor of two, a two stop by a factor of four and a three stop by a factor of eight.

• First picture with the filter was shot with a one stop graduated filter. Note that this is the mildest result, just barely retaining detail in the clouds.
• A two stop graduated filter was used in the second image. This one produces the most balanced result in this case, darkening the clouds enough to give an image that’s closest to the way the scene looked at the time.
• Third image was shot with a three stop graduated filter. This one has darkened the clouds too much, producing a heavy effect that is at odds to the way the scene actually looked.

Notice in each case, that only the sky is affected! The filters were placed with the transition zone right over the horizon, so the foreground grass is just as bright seen through the filter as it is on the sides and bottom of the frame.

http://i.imgur.com/Rz9zhO5.jpg

In the field, the filters aren’t held as they've been shown above – they are attached to the front of the lens via an adapter ring and a rotating filter holder, as seen in the image above.

This setup allows the filter to be moved up and down as well as rotated, permitting the photographer to position it exactly as they wish. The holder also allows multiple filters to be held simultaneously. This is useful when stronger filtration is needed than the darkest filter you have. Two filters, positioned the same way, will behave like a single, stronger one.

In general, if the scene has a contrast range that exceeds the dynamic range of your camera, use of these filters is a must.

Polaryzing Filters

Polarizing filters can increase colour saturation and decrease reflections — and are one of the only lens filters which cannot be replicated using digital photo editing.
Polarizers are placed in front of your camera lens, and work by filtering out sunlight which has been directly reflected toward the camera at specific angles.

• A polarizing filter will be capable of its maximum effect when one's line of sight (in red below) is perpendicular to the direction of the sun:

http://i.imgur.com/oY3ioTM.png

A good way to visualize this is to aim your pointer finger at the sun while holding your thumb straight up. Everywhere your thumb points when you rotate your hand (while still pointing at the sun) is where the polarizer is capable of the strongest impact.

However, just because the filter is capable of its maximum effect in the above directions, this doesn't necessarily mean this is where the image will appear most effected. Rotating your filter will toggle the angle (relative to the sun) that appears most polarized.


• One of the first characteristics that you're likely to notice with polarizers is how they increase colour saturation:

http://i.imgur.com/dXrSds0.png

When direct reflections are reduced, a greater fraction of the subject's light is of the diffuse variety — resulting in a more colourful representation. Foliage will be rendered with a brighter green, skies will have a deeper blue and flowers will appear more intense.

• Polarizing filters reduce contrast. Since polarizers reduce direct reflections, this often has the consequence of also reducing image contrast. This can make it easier to capture scenes with a broad dynamic range, such as trying to balance a bright sky with relatively unreflective land (which can even make using a graduated neutral density filter or high dynamic range less important).
However, less glare/contrast is sometimes undesirable. In the example below, the artistic intent was to (literally) highlight the curving road by portraying it in stark contrast to its surroundings. Using a polarizer actually detracted from this goal:

http://i.imgur.com/CJZSEVm.png

In other situations polarizers can instead increase contrast. In the next example, the polarizer increased contrast by filtering the light reflecting off of the haze and sea spray. This effect appears most pronounced in the hills and the puffy clouds directly overhead:

http://i.imgur.com/Ff18tqS.png

More will be added about other kinds of filters.