Correctly exposing light colours

sarboo

sarboo

Messages
57
Name
Sarb
Edit My Images
No
Hullo :wave:

What do you do when you have a very dark background but the thing or person you're taking a pic of is very light? I recently took some pics of a friend's baby at a christening and she had on bright white clothes....she came out as a big white blob, basically :|

Ta! :)
 
You need to think about how the camera views the scene and what it is metering. I assume you have your camera set to Evaluative, in which case it views the whole scene and tries to get an overall 18% grey value, so if there is a lot of dark background it is going to think hey not much light here I need to increase the exposure, hence anything that is light is going to be overexposed. The reverse happens with a lot of snow, camera thinks it's bright compensates for that and you end up with dull grey snow.

So you need to understand what the camera is seeing, you can of course use Spot metering where it will evaluate on a small central area and this method can be useful in the situation you describe as the camera places less emphasis on the surrounding areas. Cameras are pretty stupid really and no match for the human brain that can apply more thought.

If using Evaluative and the primary object is bright or dark just add some exposure compensation up or down so that your intended target is correctly exposed. Doing this may mean you have to compromise on the other bits being either under or overexposed, although some tweaking is possible in Post Processing in these suituations.
 
The best way is to use the histogram and (if you can) set the "blinkies".

"Blinkies" should be available somewhere in your menu - possibly as some kind of overexposure warning - someone with a 40D will be able to tell you more - and what happens when set is that a part of the image on the back of your camera will flash on and off to warn you of any parts that are overexposed.

You can then adjust your exposure to get a properly exposed image.

.
 
sarboo said:
Hullo :wave:

What do you do when you have a very dark background but the thing or person you're taking a pic of is very light? I recently took some pics of a friend's baby at a christening and she had on bright white clothes....she came out as a big white blob, basically :|

Ta! :)
Click to expand...

This is a situation, most, if not all of us have experienced at some time, early on in our learning curve.
This type of shot is one of the hardest to get right (especially) if we let the camera set the exposure using the normal 'in camera ' setting as has been mentioned, the camera is trying to evaluate the whole scene as 18% grey (a sort of default average scene setting).
Where we have the extremes of light e.g light objects against a black background, or, dark objects against light (white) background, the camera gets it wrong.
This is where you can do one of two things,
1/ switch to spot metering if available, and meter on the light object (in your case)
2/ use exposure compensation (negative in your case) - how much compensation you need to find out by experimentation. Use -1, -1.5 -2 etc on multiple shots of same object and compare results.

simple rule - light object on dark background use negative compensation (it takes some light out of the scene if you like).
Dark object on light background e.g snow - use positive exposure compensation e.g add more light.

it might appear back to front, but you are compensating for the camera's lack of inteligence when it comes to exposure.
It's all that rotten Mr 18% grey thats at fault. :naughty:
 
You must log in or register to reply here.
Back
Top