View Full Version : Contrast

Alan T. Price
June 9th, 2007, 08:13 AM
When I use the contrast setting in my 1D2 I have the choice of 5 values ranging from -2 through 0 to +2. When I load a raw file into DPP version 3 the contrast value matches the camera selection (-2 to +2) but there is an extended range of -4 to +4 that I can now choose.

Here's my primary question: Which value of contrast in DPP or in the 1D2 parameters best coresponds to the correct scene contrast - the one presented to the camera by the lens ?

A secondary question: Is the "correct" setting for the 20D any different ?

It should be easy for me to look at the screen and say this looks best or that looks best but it is rather subjective and for this exercise I don't want to know what looks best - I want to know what looks natural. Usually I want what is most realistic but of course sometimes I have to tweak it to extract some details from light or dark areas.

Can anyone answer this for me with any degree of certainty ?

Thanks in advance.

- Alan

June 9th, 2007, 10:20 AM
I can't guarantee any degree of certainty, but my understanding is that a value of 0 produces the contrast level that was presented to the camera by the lens. I would also assume this applies to all cameras.

Alan T. Price
June 12th, 2007, 08:55 AM
Yes, that was my expectation too but as it is subjective I was hoping to hear from someone who knows the camera specs or else has done some measurements to confirm it. Otherwise I'll have to set up an experiment myself. I just hate re-inventing wheels unnecessarily.

cheers Kris.

Don Lashier
June 12th, 2007, 12:11 PM
There is no "correct" contrast setting - even if you set to 0, a contrast curve of sorts will be applied (the default film curve). If you were to view with "correct" (scene) contrast the image would look very flat in most cases. The reason for this is that the DR of the viewing medium is much less than the actual scene DR, and the contrast (midtone in particular) must be boosted in order to view the image with any resemblence to the actual scene.

The second point is that the contrast that should be applied to make a scene look "natural" is very dependent upon the scene (content of the image) in question, and also to some degree on the characteristics of the viewing medium (monitor, printer). Sure there are settings which work (are in the ballpark) "on average", and this is probably close to the default (0) setting.

- DL

Steve Saunders
June 13th, 2007, 06:05 AM
I agree with Don and that's why many people shooting RAW prefer to set the contrast at 0 and adjust later on. Not that it matters really when shooting RAW as the settings you apply are tagged onto the RAW file and only applied when you open them in your RAW conversion program.
With Jpegs you might have to be more careful, I find setting a higher contrast level can cause problems (such as too high a contrast setting in sunlight) later on in certain situations and I often wish I've left it alone and adjusted the contrast in PS later on instead. It's easier to boost contrast in a flattish image later on while still preserving detail, than it is to reduce contrast.