While using Tv Override, the small bar of info at the bottom (NOT part of CHDK, in Canon's Firmware) that displays aperture, shutter speed, etc., displays the wrong Ev value, for example, when I set the Ev Override value to 1/250, the info bar says 1/40. Is this normal? Is there any way to change this??
Some ports do show the override value in the Canon UI, but I don't see anything obviously wrong on elph110. CHDK can show the override in the UI, if you have "Show State Displays" enabled in OSD options.
For the Canon firmware, the only possibility I see is if the TV2 propcase value is incorrect. You can check this
In the CHDK menu, go to "Miscellaneous Stuff->Debug Parameters"
set "Debug data display to props"
set PropCase/ParamsData Page to 26
When you leave the menu you should see a list of numbers on the screen like
260: 0
261: ...
Make sure CHDK Tv override is *NOT* enabled
Leave alt mode, half press the shutter until the camera is ready to shoot, note the shutter speed the Canon firmware displayed, then release
Post the values after 265 and 266 and the Canon shutter speed.
Also, when I use Tv Override, the preview of the image on the LCD display looks fine, but the final image is always underexposed or overexposed. Is there a way to get a more accurate preview?
Unfortunately, CHDK shutter override generally doesn't affect the preview.
You can get an idea of what the effect will be by comparing the value Canon chooses compared to your override, e.g. if the Canon UI shows 1/30 and you override to 1/250, that's about 3 stops so your picture is going to be pretty dark.