Reds - Why so hard to shoot?

xendless xurbia · April 13, 2009

Hey guys,

Quick question here. I've been looking through some photo's I'd taken on a recent walk around the block. One thing I noticed was that most of the shots that had vibrant red's in them, such as flowers or even red cars, almost no detail was left where the vibrant reds were situated. Then I looked through some old photo's, and noticed that huge amount of red's were blown out, while the rest of the photo is in perfect harmony.

I'm a Nikon shooter and have noticed this with the D70s, D300 and D90. Not sure if you guys are experiencing this. But if you are or have, do you know of any work around?

And I always use the Neutral profile when shooting RAW.
When shooting JPEG, I shoot Standard +1 saturation.
No D-Lighting
Contrast set to 0

One thing I have realized is that Nikon actually put a lot of emphasis on the red channel. Photo's do come out a lot warmer than Canon's and Oly's from what I see. Not sure if this warming has to do with the heavy read channel.

Thanks,

Jason

pathfinder · April 13, 2009

Set your histogram up so that you can see each of the Red, Green, and Blue channels. You will quickly see if one channel is fried when you have a large spike at the right of the histogram in one channel only. This is not unique to Nikon, we folks in Canon land have the same issue.

As you noticed, red flowers frequently overload the red channel long before the green or blue channels. You need to know this in advance, so that you can alter your exposure at the time.

Nikolai · April 13, 2009

I may be hugely mistaken, but I vaguely remember something to the point of Sony making chips for Nikon (at least until recently). And, for whatever reason, Sony's chips were always oversaturating red...

Other than than what Jim said is totally true. Remember, all auto-exposing cameras are trying to create a nice solid 50% gray rectangle. So if one ot the channels or frame areas is way out of average saturation- or luminosity-wise, the camera would try to compensate for it by moving everything else in the opposite directioin to reach its beloved uniform gray. You must know these thigns and don't let it.

pathfinder · April 13, 2009

As Nik mentioned, ALL light meters in cameras are REFLECTED light meters - that is to say they measure the amount of light reflected by a subject. The difficulty with that design, is that the meter does not know if the reflecting surface is white, black, red, or blue, and so the designer's of reflected light meters "ASSUME" and "ASSIGN" a reflectance of neutral 50% gray to a metered scene. An Incident light meter does not share this design flaw, because it reads incident light shining on the subject only.

This is why if we meter snow scenes and use the camera meter readings without interpretation, the image comes back a flat gray, instead of shining white, unless we add about +2 stops of exposure compensation. Likewise, if we meter a black cat in a coal mine, it will come out gray also, unless we adjust the meter reading with about - 2 stops of exposure compensation.

In the case of the very red tulip, the flower is intensely red, but the blue and green light is almost zero, so the meter reads the flower as very dark, and increases the aperture and shutter speed to allow a lot more light, a lot more than is actually needed, and hence, blows out the red channel.

As I said earlier, the real solution is to keep an eye on your histogram with the Red, Green and Blue channels displayed. If you use the single Luminosity channel in your histogram, you will get surprised from time to time.

xendless xurbia · April 16, 2009

Perfect. Thanks for the answer guys. I've tested it, and yes, dialing in negative exposure comp seems to work quite well. But the downfall is that i seem to loose saturation. The red's don't look as red.

Another work around I've found is in post. Duplicate the layer, replace the red channel with the green channel, and set the layer mode to Luminosity. It seems to keep the color and increase the contrast and detail.

pathfinder · April 16, 2009

xendless xurbia wrote:

Perfect. Thanks for the answer guys. I've tested it, and yes, dialing in negative exposure comp seems to work quite well. But the downfall is that i seem to loose saturation. The red's don't look as red.

Another work around I've found is in post. Duplicate the layer, replace the red channel with the green channel, and set the layer mode to Luminosity. It seems to keep the color and increase the contrast and detail.

Once red reaches 255,0,0 in RGB color spca that is as far as it can go. In LAB, of course, you can create colors that are much more red and much brighter at the same time - indeed, impossible colors, seen no where, except maybe in a ruby laser beam.

There are a number of post processing techniques that can work if the channel is not totally fried, but that is a topic for Finishing School and not Technique, so I did not really go into that discussion here.

I seem to remember something about using the K channel to increase the detail in the Red channel as well.

dlplumer · April 16, 2009

Very useful and informative discussion.

Reds - Why so hard to shoot?

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