Quote Originally Posted by Johnny Rasmussen


Hmm, that is odd. The only other thing I can think off is that there may be something wrong with the installation files. I know it sounds unlikely but I can not think off any other reason. Have never seen this before...I remember my wife had a problem with DPP a couple of years ago. The RAW tab or the RGB tab menus did not work properly. I had to do a clean install with "fresh" files from Canon to get it to work.


A clean install is a good idea, and might even work! So, if you decide to try it, let us know if that does the trick. [:P]


Actually, I'm serious (for once). Assuming we are correct in thinking the white area of the plot shows the theoretical dynamic range of the sensor, I suggest that you try it because I believe DPP on my computer is showing the correct data and DPP on your computer is not behaving correctly, for two reasons - one logical, and one empirical.


The logical reason goes like this: if we're correct that the 'white area' on the DPP histogram represents the theoretical maximum dynamic range of the camera, then an image from a camera with a 14-bit analog-to-digital converter (like the 40D)should have awider white area on the graph than an image from a camera with a 12-bit ADC (like the original 5D). (You can confirm the bit depths here.) So, the image below (not mine, as I said) would seem to be correct:








The empirical reason goes like this: I downloaded a Rebel XS/1000D RAW file from Imaging Resource, and the equivalent 7D RAW file (thanks for the link above!!). Opening both in DPP 3.8.2 on my computer, I see this (XS on the left, 7D on the right):


[img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.35.15/1000D-RAW-histogram.jpg[/img] [img]/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.00.35.15/7D-RAW-histogram.jpg[/img]


It seems that my DPP RAW histogram shows a 2-unit wider dynamic range for the 7D (14-bit) than the Rebel XS (12-bit), starting at -11 vs. -9. The 2-unit difference on a base-2 log scale corresponds to the 2-bit difference between the ADCs of the two cameras [since log<sub>2</sub>(2<sup>x</sup>) = x].


However, the screenshots you posted from 14-bit cameras seem to be showing the same dynamic range as the 12-bit Rebel XS in DPP on my computer - that's what makes me think yours is not displaying correctly. If you're willing, try downloading the same two files linked above, and see what your computer shows (maybe there will still be a 2-unit difference, offset to -9 vs. -7 in your case, and we'll be back to square one!).


I hope the above makes sense. Thanks for taking the time to stick with this, Johnny!


--John