Unfortunately, this build takes away the ability to override AV [aperture] settings and instead offers ND filter state OFF, IN or OUT. The Canon SD800 IS supports variable apertures [e.g. 2.8, 3.5, 4.0, 4.5, 5.0, 5.8], so it is not as simple as selecting the ND filter IN or OUT. In Build #50, you could select an override for aperture, but I don't know if it really works.
On the Ixus series Canon emulates the aperture by the ND filter, they have no mechanical aperture (iris), in earlier builds there was left copied code from other models, that's why there were those settings...
I'm not sure whether it could be helpful on the Ixus models to use this "aperture settings" again to set up an aperture value and then let the Canon firmware do the settings to emulate this...perhaps i'll find some time to check this...
I'm not clear on all the implications of this but it is my understanding that the SD series has no aperture or aperture control per se, and only mimics that with the ND. Thus it's not clear to me what "aperture control" means in this context.
You'll get the max. F-stop (e.g. F8.0 on SD870) with ND filter IN & min. F-stop with ND filter OUT (F2.8 ), that's the aperture emulation on the Ixus series (i think also in combination with other settings like shutter speed, ISO...)
The biggest deficiency that I have discovered with CHDK with the Canon SD800 IS, like you mentioned above, is that after you have taken a photo and you flip to Display to review your image with detailed shooting information, you don't see the settings for ISO, TV or AV that were used to generate the image. Of course, I can use a program [e.g. BreezeBrowser] external to the camera to display the *.DNG file and see the EXIF metadata, but you really need to see this data in the camera, as you can with a DSLR [e.g. Canon EOS 40D]...
Yes, that's a problem, the Canon OSD (and the review) always show the "Canon" values, not the "real" ones; you can't trust the Exif data, sometimes a look to the histogram may help.
I was quite surprised to discover that CR2 files, right out of the SD800 IS camera, can be read by BreezeBrowser software but not by Photoshop CS3. Even if Photoshop could read the file, you should still Convert to DNG files because this is how you port the EXIF data from the JPG file to the raw file [DNG].
dng4ps-2 adds a DNG standard header (including the Exif data) to the raw file, some other usefull things like compressing (lossless) the RAW image or adding white balance information (if the camera is supported) can also be done...
Here is another major deficiency: If you delete an image from within the camera, it will do the usual and delete the JPG file, but it won't deleted the CR2 raw file for that same image.
There's an option in the filebrowser menu (you'll find it in "Miscellaneous stuff") on some newer builds (Juciphox, perhaps latest
Autobuild but not sure) called "Purge raw", more informatins in this post:
Erase JPG along with corresponding CRW in any folder.