Today's lesson is about how your camera fundamentally works and how to use that to your advantage. These rules apply to both still photo cameras and a video cameras, but we are focusing specifically on video cameras for the sake of this conversation.
There are a lot of ways you can manipulate the video you are capturing. But fundamentally there are three factors that are crucial to capturing video.
1. How much light you are letting into the camera. This is usually adjusted by the iris, exposure or aperture setting.
2. How sensitive your camera is to light. This is usually adjusted by the gain, iso or asa setting.
3. How zoomed in you are. The focal length of your lens.
*We won't talk about shutter speed, but in the case of still cameras shutter speed is a fundamental factor in capturing images.
We'll start with light. Light is what makes a camera work, I won't get into the physics of it but if you understand how a camera reacts to light you will be a much better film maker. Basically your camera lets in a specific amount of light which affects how underexposed (dark) or overexposed (light) the resulting video is. In most cases (unless you have a completely automatic camera) you can influence the amount of light being let in by adjusting the iris (sometimes called exposure or aperture). The iris is literally a ring that opens and closes to let in more or less light. It looks likes this...
The more light your camera lets in the more exposed (lighter) your image. Also affecting exposure is how sensitive your camera is to light. On most video camera's this is called gain. On digital still cameras it's called ISO and when shooting film it's sometimes refereed to as ASA. Video cameras deal with gain a few different ways. If you have a fully automatic camera you have no control over gain, but what you'll probably notice is that when you shoot footage at night or indoors, without much light, your footage look grainy. Some video camera's activate gain as a function of the iris. Say for example you adjust the iris to let in as much light as possible, at this point, on many cameras, you can go a couple of steps further, thus activating gain. Gain artificially lightens your image. The draw back to using gain is that it produces a grainy image that in most cases looks pretty bad. There are some video cameras that treat gain as a separate function outside of the iris.
Generally speaking it's best not to use gain. If you want your image to look grainy I recommend adding a filter in the editing process. However sometimes gain can not be avoided.
Chances are you have your camera set to automatic and you are not even touching the iris or gain settings. If you can, try to set your camera to manual. This well let you control the exact exposure you want. For example if you were trying to achieve a dark and moody look and your camera is set to auto it will not allow you to shoot the scene dark and moody. It will try to compensate by artificially brightening your image. It will add gain, thus giving you a brighter grainier look than you wanted. GO MANUAL. It's a bit intimidating at first, but you will have much more control over your images.
Next, focal length. WTF is focal length? In plain English, focal length is how zoomed in or out you are. Professional lenses on a still camera, motion picture film camera or HD video camera have clear indicators that tell you what focal length you are shooting as you adjust them. This is refereed to in millimeters. For example I might shoot a scene with my lens at 50mm. If you are using a consumer level video camera you most likely won't have a clue what focal length you are shooting at. So let's make it easy and assume you are at one of three focal lengths. First, you are zoomed in all the way. Two, you are zoomed out all the way. Three, you are somewhere in the middle.
You may be thinking, I already now how to zoom my damn camera Lost. Of course you do, but do you know the artifacts of what happens at these different focal lengths?
Zoomed out... When you are zoomed out the lens is letting more light into the camera, which means your iris may open even more to make your scene brighter. Most importantly though zooming out all the way gives you a huge depth of field. WTF is depth of field? Depth of field is basically how much of what you are shooting is in focus. Here are a couple examples....
Look at the two images above. The first one has a deeper depth of field (more is in focus) the other has a shallow depth of field (less is in focus). Two things affect depth of field. Focal length (how zoomed in our out you are) and iris (aperture). When you open your iris to let in more light you get a shallower depth of field, like the image on the bottom. When you close down your iris to let in less light you get more depth of field like the top image. The same thing happens with zooming in and out. Zoomed in = shallow depth of field like the image on bottom. Zoomed out = more depth of field like the image on top.
Why is this important?
Video cameras are infamous for having a very deep depth of field. If you want your footage to look more like film you should zoom in. this will give you a shallower DOF and make your footage appear more film-like.
On the other hand if you a have a wide shot of hundreds of zombies storming a city you may want to get as many of them in focus as possible, in which case you would zoom out and close down your iris as much as possible.
I encourage you all to mess around with your cameras and see what happens when you play with these settings.
Feel free to post your questions in the comments field below as well as any recommendations for subjects you'd like me to cover.