40D - Noise and DR Chart

This chart which was posted on DPR by John Sheehy may be of interest to 40D owners. Although the figures are taken from the examination of only one camera and are therefore not exact, they are in general agreement with the tests on the 30D which showed that the intermediate ISO stops 1/3 up from the even hundreds are best avoided and the the 2/3 up increments give the best noise performance but at the cost of some headroom for the highlights.

The chart is from this thread:
http://forums.dpreview​.com …rum=1019&messag​e=25086574

Sheehy's findings are in general agreement with observations I have made myself. The second image shows the clipping present in linear conversions of RAWs shot at the same exposure at 400, 500 and 640 ISO.

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Can you elaborate on the theory behind all this ?
TIA

also are there charts for other cameras? ie 20d, xt etc? This will give people an idea on how much noise improvement can be expected after an upgrade.

I'm impressed by the DR at ISO100. I always thought ISO200 offered a noticeable about more, but I don't think .1 stops is going to matter.

Thanks for the info

Thank you very much for this information.