Just about every Digital SLR camera sold these days comes with a small plastic part that most people don't give a second thought to. What is it? How is it used? Plus, why is it so important if you are shooting time-lapse?
What is it?
It's an Eyepiece Cover, usually black like most items used in photography and film-making. Most eyepiece covers can be attached to your camera strap so it is always close by. Don't even think about going out to shoot time-lapse without it.
How is it used?
Basically most eyepiece covers slide from top to bottom overtop of your viewfinder essenially blocking any light from entering the viewfinder. As pictured below you can see how the Canon cover has been slid over the eyepiece. One disadvantge is that once it's attached you can no longer look thought the viewfinder to frame your shot. More about that later.
|Nikon Eyepiece Cover||Canon Cover on Strap|
Why is it so important if you are shooting time-lapse?
Ok, here is the really important stuff that lets you know why this eyepiece thing is invaluable. Consider this, normally when you are shooting stills you always have your eye up against the viewfinder, on the other hand when you are shooting a series of time-lapse images you usually have backed away from your camera. This is because you don't want to bump your camera in any way. Now let's say your camera is set to Apeture Priority meaning that you have manually set the Apeture, the camera is now caluclating the shutter speed based upon the amount of light entering the lens. Or is it? That all depends, if you have your eye up againt the eyepiece it is, but say your eye is not against the eyepiece. What then? Suprisingly if your eye is not against the eyepiece light will enter through the eyepiece and give your light meter a false reading. The light entering the lens and the light entering the eyepiece are combined giving you an incorrect shutter speed. You only want the light from the lens metered in order to have the camera's shutter at the correct speed. There you have it. When you slip the eyepiece cover overtop of your viewfinder you are effectively ensuring that your camera's light meter gives you a proper reading for each and every frame you shoot.
In a nutshell you want to ensure that all your camera settings, framing, lens options, tripod, etc, etc, are all set first. The last thing you should do is cover the eyepiece using the small plastic cover which came with your camera. Once you've done that fire up your handy dandy Pclix XT and shoot your time-laspe sequence. If you have any questions or thoughts add them as a comment below and they shall be answered. Happy Shooting everyone.