How to avoid blown colours in one channel?

Question

I've recently bought a Canon 700D and am still very new to it, although I have a good reasonably good understanding of photography basics (aperture, shutter speed, ISO, DOF, focal length etc.)

I mostly shoot in Av mode.

I've noticed on a few photos that the colours are getting blown out - not as a general exposure thing, but on one channel, e.g. red. This is losing all the detail in, say, Autumn leaves. My last camera suffered with this and I would overcome it by under exposing, shooting raw and post-processing myself, but I'd sort of hoped that this one would be a bit better.

Here's an example (the black bits are clipped highlights - clipped on red channel):

Is there anything I can do about this? Should I always look out for strong colours and dial down the automatic exposure?

Answer 1

You hit the nail on the head with the bit about watching for strong reds and dialing down the exposure. For some reason, it seems like everything blows red if there is a strong red, from the low to the high end and regardless of manufacturer. You just have to watch for it and be careful. I'm not aware of any other kind of fix.

Answer 2

There are a couple of things you can do to help mitigate problems with blowing the red colour channel:

• Shoot with a cyan filter. This will effectively under expose just the red channel. This can be useful if for example you're shooting in low light and your scene contains data in the blue channel, which would otherwise become noisy. However this approach also has negatives (having to purchase filters, risk of flare).

• Use UniWB. The histogram on the back of the camera pulls data from the embedded JPEG of a RAW file. The camera is actually quite a lot less sensitive to red (and to a lesser extent blue) light, hence red and blue are usually boosted to obtain correct white balance. Since the white balance setting in camera is useless when shooting RAW, you can trick the camera into not boosting any colour channel, thus giving you a more accurate RAW histogram, showing which colour channels are close to clipping. Essentially setting UniWB entails displaying a magenta colour on your computer monitor, taking an image and instructing your cameras custom WB function that that is "white". More detailed instructions can be found here.

• Bracket. Very few reasons not to bracket your exposures if you have the time/space available.