 Ujjwal Mukherjee |
Photography on Snow/Sand Hi! This question is bugging me for a long time. When taking photo's on a bright snow covered mountain or bright sand it has been advised to increase the f-stop by 2 over the camera's reading and take the photo. Will someone please explain it with an exaxmple. Like if the camera reading of the view is f/11 and 1/125 for a 100 ISO film what changes need to be done to take the photo. Will it be different if the background is clouded or dark. If yes what will be the setting for the same case.
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Jeff S. Kennedy |
This is a rule of thumb and like all rules of thumb it depends on a few factors. If your meter can take spot readings it becomes less critical to compensate. For your example, if you are shooting a picture with a snow covered field and your meter is reading the whole area the snow will be the predominant feature. Your meter tells you the correct exposure to make the scene appear 18% gray. Of course the snow is white so this isn't what you want. So if the meter indicates f11 @ 1/125 you need to open up 2 stops to make the snow appear white. Something like f5.6 @ 1/125 or f11 @ 1/30. If you can spot meter you can meter off of something in the scene that is 18% gray. In which case you need not compensate. When I take a reflective reading under these conditions I meter off of the palm of my hand (works with or without spot metering as long as your palm fills the frame) and open up 1 stop. But this really isn't any different than metering the snow and opening up two stops.
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Ujjwal Mukherjee |
Thanks a ton for the tip Jeff! One clarification related in making changes over camera's recommended meter reading: when I open up 2 stops or slow down by 1 or 2 stops, I 'll need to put my camera in manual mode and make the changes. I had experienced earlier that the camera'a exposure compensation meter starting giving signal of either over exposure or under exposure reading. I assume in this also since I am opening up 2 stop's over it's recommended reading my camera's (Canon EOS Elan II) will probably indicate an overexposure. Should I go ahead and take the picture ignoring it? The other clarification that I'll need if you can explain in details what is the 18% grey area of the scene.
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Jeff S. Kennedy |
Yes, since your camera's meter is trying to achieve 18% grey if you deviate from it's recommended exposure it will let you know that (in it's uneducated opinion) you are either over or underexposing the shot. Just ignore it and do what's right. Now you're a photographer and not a snap shooter! 18% grey takes some time to recognize. Basically, it is any tone in the scene that when shot in black and white will record as 18% gray. The color of it doesn't matter, just the tone. Is it necessary to always meter a mid tone (18% grey)? No. As in the example you can meter off of pure white and open up 2 stops. Or meter off of a white skin tone and open up one. Metering off of a mid tone is just convenient because you don't have to compensate.
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Rob Kenning |
One tip I can offer in the quest to simulate 18% grey cards is to use a typical newpaper. I have used this method quite successfully in the studio.
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Jon Close |
Note that opening 2 stops for a bright snow or white sandy beach scene and other exposure compensation rules of thumb are based on the common centerweighted average metering. The sophisticated algorithms used in multi-zone Canon Evaluative and Nikon Matrix metering (and Minolta, Pentax?) will attempt to make these exposure compensations automatically. For example: for bright scenes (above EV15) the Canon system will automatically add overexposure. See question http://bobatkins.com/photography/eosfaq/eosfaq24/0toc.html (Miscellany Q.20) and http://www.camera.canon.com.my/photography/art/art14/
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