Originally Posted by
Tim Dodd
Roger,
This thread is about the Canon 40D and 1D3. The remarks I've made should be taken specifically within the context of this thread and hence those two cameras. My comments are not intended to apply to cameras outwith the Canon brand. I should also make it doubly clear that unless otherwise stated, my remarks are intended to apply to raw shooters, not JPEG shooters.
With that out of the way, are you saying that the things I have said and the article I have referenced are invalid, even if only in parts, for the two cameras under discussion here? If I have made an error can you please help me out and explain in lay terms whereabouts I have made a factually incorrect statement with respect to the 40D and 1D3? I'm more than happy to be corrected, and to learn, if I am wrong. I just happen to think that I am not wrong.
If I can try to help things along, which of the following assertions do you disagree with....?
1. Expanded ISO settings are nothing more than digitally multiplied derivations of data captured at lower ISOs (for all Canon cameras released to date, including both H and L expansions).
2. Intermediate ISO settings between the full stop ISO settings of 100, 200, 400 etc. are nothing more that digitally multiplied/divided derivations of data captured at the nearest one of the "full stop" ISOs (for the 40D).
3. HTP effects an underexposure of 1 stop at the sensor, via a deliberate reduction in actual ISO and than digitally manipulates the JPEG data (not the raw) to generate an image file which captures increased dynamic range in the highlights.
4. If you shoot to raw only, HTP accomplishes little or nothing that you could not do for yourself by underexposing by one stop with your ISO setting and then fixing with your own custom tone curve in editing.
5. Processed within DPP on default settings, a shot taken with HTP enabled will result in higher shadow noise than an image shot with the same nominal exposure settings but with HTP disabled.
If I've missed a key point then please feel free to comment on that as well.
Thanks.