Posted 07 July 2007 - 10:03 PM
Posted 07 July 2007 - 11:22 PM
Exposure choices are partially artistic, so different people will handle it differently. Some will expose to show what's in the shadows, others will expose to show what's in the highlights. The decision usually depends on the scene and the subject. If you want maximum flexibility in post, you'll typically try not to overexpose or underexpose anything, but that's frequently difficult because the range of light in sun and shadow is too extreme to capture everything. If you're shooting digitally, the vast majority of people choose to underexpose. If an object in the scene is supposed to be really bright, like a light-bulb, then the scene can be overexposed a little, letting those lights wash out to pure white. For instance, I would let the overhead sun get blown out if I was shooting outdoors, and instead I would try to set the exposure so the overall sky was well lit.
Hello sorry if my english is not good. Im confused with exposure. I dont seem to understand when it is right to under or overexpose. I know a shot that is regular the reading will be good. Night time should be underexposed too. Im confused with intances that you use diffusion or flag to make a scene less bright. Does that mean you need to under expose to? If the level of light is low does the meter give the right reading or make it to light.
At night, if you are trying to film what's in the shadows, then you'll have to overexpose in order to brighten up the darkness. If you want to emphasize just how dark everything is then you can expose for street lamps or whatever other lights exist and then the darkness will remain black and difficult to make out. There's a balance between showing the objects in the shadows versus them the objects looking like they're in a weirdly colored daylight. If you're recording fireworks, you'll want to set the exposure to underexpose by a lot, in order to show the extremely bright trails of light. The same holds true for night-time fireball explosions and such.
Diffusion will soften the picture, and in the process it might happen to make the shadows a touch lighter and the highlights a touch darker, but it's an extremely minimal change, almost unnoticeable. For that reason, the effect of diffusion is usually to gain the softness and not to influence exposure.
Meters measure whatever light reaches them. They will tell you to use longer exposures when they don't get hit with much light, such as in the middle of a dark field at night. The will tell you to use short exposures if you hold the meter in a flashlight's beam. You have to take into account the environment, where the lights are, and what you want the final picture to look like. Getting a good exposure requires practice, a bit of intuition, and more practice.