28.1.11

Colour Compensation

Have you ever noticed that sometimes, despite apparently exposing your photo correctly it ends up looking a little wishy-washy and blah? To understand a common reason why this happens you need to understand how the camera's light meter measures light.

Camera's "meter" (read light) by sampling areas within your camera's frame and deciding what settings will, on average, bring everything back to a mid-grey.  This generally works pretty well, but a camera's internal light meter tends to "make mistakes" when you are taking pictures with extremely bright or dark areas or if there is a lot of white or black in your photos.


How to adjust the bright/shade problem in photos is a topic for another week.  The other problem you run into is when you are dealing with mostly white or mostly black photos.  It is not surprising that, with the camera's light meter trying to make everything mid-grey, photos with lots of white or lots of black will tend to look grey if you take your photo with the exposure settings that the camera suggests.

Yesterday I took a walk in the forest and took a lot of photos of the fresh snow. Perfect opportunity to take some picture to show you how to think for your camera when photographing whites and blacks.
In the first photo I used the settings that the camera suggested - it's pretty dark and the white is a little grey.  The second photo is better and by over-exposing the photo to two stops (+2) above what was suggested by the camera's in-built light meter I got a photo I was happy with.
Finished photo - which has been sharpened slightly for the web.

The same concept applies for photos mostly of black.  The camera slightly over-exposes black to try to bring the tones back to mid-grey.  If we trick the camera by under-exposing the image slightly our blacks will be true black.

But how much should we over or under expose in normal conditions?  Well that depends on the photograph and what you want to be correctly exposed.  White and Black tend to need around 2 stops over or under exposure to get the correct colour.  Mid-green, red and mid-blue will generally be correctly exposed at the "true exposure reading".  Colours brigher than red (yellow, orange, skin tones) will need anywhere between +0.5 and +2 stops and darker colours will fall somewhere between -0.5 and -2.0
Barn Door

Metering using an external light meter, or grey-scale card is a much more accurate way of correctly exposing a shot, but the loose rule-of-thumb above will take your photos a long way.  If it doesn't work out you can always change your settings and take another photo.  

Intentionally over or under-exposing your photos is possible in all modes on your dSLR cameras, some bridge cameras and even some point-and-shoot cameras (although it is by far the easiest to manipulate when you use manual mode).

13 comments:

urban muser said...

great information here! thanks for sharing all this.

onagracenote said...

Excellent post Clare. I've found it difficult to get the exposure right for black and white photos and this is very helpful. Your photos are lovely. Thanks for sharing and have a lovely weekend. Di

justine said...

excellent post

Anika said...

Another post with a wealth of information. I like this to trick my camera INTO taking wishy washy images too!

Karli said...

Oh yes! Story of my life - LOL! I know to overexpose or underexpose in certain situations, but I struggle to know how "much"... and really get it right. When it's non-kid shots, I can fiddle around with it, but with my kids...sometimes I get one chance to "guess" and get it right! :-) Doesn't always happen - LOL! GREAT information! Happy Friday and have a wonderful weekend. XO

Kelly said...

great tips again! thank you!

Krystal said...

I loved reading this, I will have to figure out how to go 2 up or down. I think I'm getting motivated again, it was touch and go there for awhile!

Jamie said...

More great info - I swear one of these weekends I'm going to take all your know-how posts and work my way through them. I know I'd walk away a better photographer.

lisa said...

Fantastic information Clare!
Thank you so much, and have a wonderful weekend!

lisa.

jamie-lee said...

this is really interesting to read - although I don't understand all the mechanics behind the settings on my camera, I've learnt the right way to play around with them - exactly what you were explaining above! x

Ashley Sisk said...

That's pretty interesting. I've recently been focusing on proper exposure but this is one more element that I need to consider. Thanks for sharing and I love that last shot.

Margaret Bednar said...

I have really enjoyed your blog this morning! I have a not very fancy Kodak and a lot to learn. I hope to get a new camera this year, but will continue plugging away for now. I look forward to following your interesting blog.

Elizabeth {e tells tales} said...

Bookmarking this! I need lessons in photography way bad.