| Joined: | Thu Apr 19th, 2012 |
| Location: | United Kingdom |
| Posts: | 4424 |
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When you take the IR images do you adjust the EV compensation.
I have seen it recommended that you overexpose by up to +1EV.
It's not a fixed formula. The scene, subject and lighting can fool the meter more so than in full colour.
In bright sunlight, even lit subjects, the exposure is quite often ok as per the meter....maybe +0.5.
But in slightly overcast weather, or with large areas of foliage not exposed to sunlight, the exposure may have to be ....reduced. This is because the meter only sees (and computes) for the visible light component. So in darker conditions it opens up the exposure without reference to the contribution from the foliage IR. These images can as aresult be over exposed .....especially burning out the highlights.
I have to say I don't ever recall having to over expose to +1.
But I do bracket -0.7 >0<+0.7 on all my shots ...as I know it's easy to misread the scene. Better to have a choice.
Having said that, the ramparts image in the above example, from the histo, is probably a good stop underexposed! ( I may have chosen the -0.7 version). But the thing to watch out for is the leading trail of pixels at the front of the curve. Move this exposure up by more than a stop and those pixels, though only few, will be clipped....giving burnt out spots in the image. Now this may not be sufficient concern but I always like to underexpose to save the highlights. After all, in IR, the 'whites' are the supposed most important part!
Last edited on Sat Jan 11th, 2014 09:33 by Eric
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Eric