Canon 1Ds Mark III — ISO 50
I’ve commented previously on digicam-like noise at ISO 200 with the Canon EOS 1Ds Mark III. But there is a solution: over the past few months I’ve experimented more and more with ISO 50 (when practical), and I’ve found that the results are worth it. While ISO 50 is not a true ISO (the tonal curve and dynamic range are different), I’m pleased with the image quality it offers. So the next time you’re shooting on a tripod, experiment with ISO 50 on the 1DsM3 (and ISO 100 on the Nikon D3). Get a Canon 1Ds Mark III at BH Photo.
The image below was processed with Daylight color balance and Neutral setting in Canon’s Digital Photo Professional—nothing was tweaked for visual appeal. At ISO 50, there is some posterization in a few areas, but given that the luminance (L) channel reads “1” (the first level over pure black), criticism is hardly warranted. A planned future comparison might well show that the Nikon D3 does better under such circumstances—that certainly is my subjective impression so far, and would not be surprising given the D3’s much larger photosites.
Rose on Green
Canon EOS 1Ds Mark III + Leica 280/4 APO, ISO 50, 1 sec
Compare the red/green/blue channels below. These are from the Wide Gamut version. There is some posterization in the blue channel.
Red/green/blue channels from Wide Gamut RGB. Note posterization in blue channel
An interesting thing happens when converting to sRGB (in 16-bit mode): posterization of the red channel, and complete loss of detail in the blue channel (pure black).
Red/green/blue channels from Wide Gamut RGB. Note posterization in blue channel
This is a good example of where the narrow-gamut sRGB color space fails miserably to preserve image detail: it can’t describe the color of this image very well at all. Using 16-bits cannot save the day; the color is out of gamut, and 16-bits can do nothing about it, which leads to the tried and true rule: use 16-bit mode in a wide-gamut color space for image manipulation.
