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[OM] Re: Green Cast (formerly E-1 related)

Subject: [OM] Re: Green Cast (formerly E-1 related)
From: Stephen Scharf <scharfsj@xxxxxxxxxxxxx>
Date: Fri, 28 Nov 2003 17:42:16 -0800

Date: Wed, 26 Nov 2003 22:17:17 -0800
From: Moose <olymoose@xxxxxxxxxxxxx>
Subject: Re: [OM] Playing with an E-1

A great example of color/brightness correction. But shouldn't the camera
get a shot like that, outdoors in sunlight, a lot closer than that in
the first place? Are you saying the the exposure was manual and the
photog blew it or the auto-exposure blew it? Can't Can*n issue revised
firmware to fix the green shift?

Moose, the camera does an excellent job of metering and, for the most part, white balance. But, as Skip said earlier, and I will concur, no camera is perfect. They all have their pluses and minuses. The photographer (Mike, one of the guys I shoot with) was shooting Shutter prority at 1/160th of a second, and had set the camera to give -1 stop expsoure compensation. This was most likely accidental. If you leave the thumbwheel on the back of the 1D turned on (there is a switch which turns it on and off, and Mike always leaves it on) and turn it accidentally, or brush it against something, it can set the exposure compensastion up or down by accident. Or sometimes in the heat of racing, you're panning the camera pretty fast, your thumb may hit and move the wheel. This is why I set my exposure compensation when necessary, and then turn OFF the thumbwheel, so I can't hit it by accident With the 1D, the exposure is usually spot on except for very bright, afternoon sun (common conditions shooting racing in California), where it tends to blow out highlight tones a little. In this situation, We set up our cameras for -1/3 stop exposure compensation. What I notice when I shoot with big glass, say my rather slow 100-400 with the 1.4X tele to give 540mm, I have to give the camera generally +1/3 expsosure to keep the image from being a little underexposed. With respect to green cast, apparently, it only does this with JPEGs and not RAW images. Canon only indirectly acknowledges the camera does this with JPEGs. They claim it is a white balance issue, and if you shoot a custom white balance under your lighting conditions, you won't have it. As I said earlier, they are very likely right, but the camera does have a tendency to render this greenish cast when using Auto White balance under some circumstances, but it is heavily dependent on lighting conditions. Sometimes I see it, most times I don't. But it occurs frequently enough that people complain about it on the Canon Forum at Rob Galbraith and DPReview. As for a fix in firmware, if it varies with lighting conditions, it seems that it might be tough for one firmware setting to correct under all conditions. You can program, in the custom functions area, alternative R/G/B settings to correct this, at least for the most part.

I think from now on, I am going set exposure with the histogram data.
If I have learned anything from my (semi)pro motorsports photography this year, it is to always pay attention to the details, even with *automatic* wunderbricks.


If I were a pro, particularly in your line of photography, I'd sure
prefer a camera that doesn't require post-processing in more than a few,
special circumstances. The difference in time spent per usable/salable
shot must be huge.

Nah, not really. It doesn't occur that much, and ofen times, when it does, "Auto Color" in PS7 does a remarkably good job of correcting it. And to be accurate, here, Moose, where it is important to maximize image quality (exposure and color) *any* image requires post-processing. It depends on the desired result and product. For web viewing, I do a minimum of post-processing, say an "Auto color" or "Levels" if there a cast, and quick levels adjustment for contrast, and a quick sharpening; doing more usually isn't necessary as the web is not a color-managed environment, anyway. Where quality is really important (e.g. a nice print) I will go through and remap the shadow, highlight and midtones using levels and curves, but I would do that regardless of source, be it slide film, print scanner, or digital camera. One of the other things I have learned this year is that there is no perfect exposure or color in an image. All of the capture media, whether it be film or digital, have flaws, as they are artificially trying to recapture the gamut of colors we can see,
-Stephen.
--


2001 CBR600F4i - Fantastic!

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