View Full Version : Reflective tonal values and right exposure
13th of February 2006 (Mon), 08:00
I am reading up on reflective tonal values and right exposures.
As we know most things reflect 18% light and they are considered mid tone values. Then we have the darks where you would under expose maybe up to -2 then snow maybe up to +2. What other subjects or colours do you change your exposure to (excluding the normal mid tones). I have read that alot of green would benefit from -2/3 exposure value. Would love some ideas and known workable exposure compensations to look out for and work with.
13th of February 2006 (Mon), 13:47
It's a more complex question than that, especially if there's a mixture of tonalities in the picture. There's an argument for deciding what tone you want where in the picture, using spot or partial metering on it with an appropriate correction to shift it to the right tonality, and using those values.
Evaluative metering can work very well if you don't want to be bothered by this, but in some situations (snow) it's going to underexpose and in other situations (largely dark picture) it's going to underexpose. Exactly how it arrives at its result is, to an extent, magic! The algorithms are proprietary, and they can be fooled.
Centre-weighted, partial and spot metering (not all cameras have all these) do not have such 'intelligence' in the metering, and are arguably more amenable to placing something at a particular tonality. When working with digital, the histogram and "blinkies" are extremely useful.
Here's a thought for you if you have a digital SLR, or other camera with M mode and a viewfinder exposure scale. Find settings that take a picture that you would regard as properly exposed, by reference to the histogram. Transfer that aperture and shutter speed into M mode, set the metering to spot or partial (whichever you have) and move around your the image, seeing what the camera's meter displays.
14th of February 2006 (Tue), 08:31
Find settings that take a picture that you would regard as properly exposed, by reference to the histogram. ... which might give you the "wrong" info if you include the sky or chrome reflections.
Gray Card…White Paper. What’s best?
Need an exposure crutch?
14th of February 2006 (Tue), 08:43
Indeed so - like all such techniques, checking the histogram can help, but if used wrongly, can throw everything out.
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