ISO
ISO measures the sensitivity of the image sensor. The same principles apply as in film photography – the lower the number the less sensitive your camera is to light and the finer the grain.
Higher ISO settings are generally used in darker situations to get faster shutter speeds. For example an indoor sports event when you want to freeze the action in lower light. However the higher the ISO you choose the noisier shots you will get.
100 ISO is generally accepted as ‘normal’ and will give you lovely crisp shots (little noise/grain).
When you do override your camera and choose a specific ISO you’ll notice that it impacts the aperture and shutter speed needed for a well exposed shot. For example – if you bumped your ISO up from 100 to 400 you’ll notice that you can shoot at higher shutter speeds and/or smaller apertures.
If there is plenty of light, I want little grain, I’m using a tripod and my subject is stationary I will generally use a pretty low ISO rating.
If it’s dark, I purposely want grain, I don’t have a tripod and/or my subject is moving I might consider increasing the ISO as it will enable me to shoot with a faster shutter speed and still expose the shot well.
Of course the trade off of this increase in ISO will be noisier shots.
Aperture
Aperture is ‘the opening in the lens.’
When you hit the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene you’re wanting to capture. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light.
Aperture is measured in ‘f-stops’.
Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also – this means if you increase one and decrease the other you let the same amount of light in – very handy to keep in mind).
One thing that causes a lot of new photographers confusion is that large apertures (where lots of light gets through) are given f/stop smaller numbers and smaller apertures (where less light gets through) have larger f-stop numbers. So f/2.8 is in fact a much larger aperture than f/22. It seems the wrong way around when you first hear it but you’ll get the hang of it.
Depth of Field (DOF) is that amount of your shot that will be in focus.
Large depth of field means that most of your image will be in focus whether it’s close to your camera or far away.
Small (or shallow) depth of field means that only part of the image will be in focus and the rest will be fuzzy.
f1.8 aperture will be used for shallow depth of field.
Higher apertures such as f16 will allow the depth of field to be large meaning almost everything in your shot will be in focus.
Shutter Speed
In film photography it was the length of time that the film was exposed to the scene you’re photographing and similarly in digital photography shutter speed is the length of time that your image sensor ‘sees’ the scene you’re attempting to capture.
Shutter speed is measured in seconds – or in most cases fractions of seconds. The bigger the denominator the faster the speed (ie 1/1000 is much faster than 1/30).
In most cases you’ll probably be using shutter speeds of 1/60th of a second or faster. This is because anything slower than this is very difficult to use without getting camera shake. Camera shake is when your camera is moving while the shutter is open and results in blur in your photos.
If you’re using a slow shutter speed (anything slower than 1/60) you will need to either use a tripod or some some type of image stabilization (more and more cameras are coming with this built in).
The surfing shot below had a shutter speed of 1/4000th of a second capturing even the splashing drops of water sharply.
Remember that thinking about Shutter Speed in isolation from the other two elements of the Exposure Triangle (aperture and ISO) is not really a good idea. As you change shutter speed you’ll need to change one or both of the other elements to compensate for it.
For example if you speed up your shutter speed one stop (for example from 1/125th to 1/250th) you’re effectively letting half as much light into your camera. To compensate for this you’ll probably need to increase your aperture one stop (for example from f16 to f11). The other alternative would be to choose a faster ISO rating (you might want to move from ISO 100 to ISO 400 for example).
Frames Per Second
Frame rate, also known as frame frequency, is the frequency (rate) at which an imaging device displays consecutive images called frames.
Advantages of a higher frame rate
Even though about 15 fps is needed to initiate the illusion of continuous motion, the effect by no means stops there. Visual studies have shown that even if one cannot distinguish discrete images, a frame rate all the way up to 60-80 fps makes footage appear more lifelike by enhancing clarity and smoothness.
HFR also minimizes the appearance of motion artifacts — especially when viewed in a theater. Moving objects may strobe or have a “picket fence” appearance as they traverse a large screen. At 24 fps, a 50 foot screen shows an object as jumping in 2 foot increments if that object takes one second to traverse the screen. This can appear as “judder” with fast panning and other types of camera movements.
Everything else being equal, one can also extract sharper and more precisely positioned stills with
HFR. This is particularly helpful when a fashion video will also be used as a stills photo shoot, or when movie frames need to be pulled for print advertising. If
HFR output isn’t needed, at 48 fps one can always use frame skipping for backward compatibility with 24 fps.