D700 - Is Red bad for digital?

Started Aug 17, 2008 | Discussions thread
Bill Janes
Senior MemberPosts: 1,510
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Re: Red actually has more headroom w/daylight
In reply to rhlpetrus, Aug 20, 2008

rhlpetrus wrote:

When shooting, check red channel histogram more carefully than
others. In my experience, even if you don't see any blinking spots
when reviewing image, red channel may still be clipped. I use aRGB
and reduced contrast as settings and import them to CNX, then check
channels, in particular red.

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Unless you have UniWB (white balance with all RGB multipliers set to 1), the color histogram will not give an accurate representation of the true status of the red channel. The multiplier for the red channel on the D3 (and presumably the D700) is nearly 2 for daylight and the red channel can easily be intact in the raw file but blown when white balance is applied as I demonstrated in a previous post on this thread. Because of this white balance multiplier, the red channel has more headroom in daylight exposures and is less likely to clip than the blue and green channels. Red clipping is often observed nonetheless because saturated reds are common in nature.

To check the true status of the red channel, you must use a program such as Rawnalize, Iris, or DCRaw where you can view the channels before any white balancing.

Also, the widest color space offered by the camera is aRGB and saturated reds can result in saturation clipping which can be eliminated in many cases by using ProPhotoRGB. With ACR, saturation clipping is indicated by color, whereas tonal clipping appears as white (see Fraser & Schewe: Real World Camera Raw with CS3).
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Bill Janes

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