Hello, if I set the ND (neutral density) filter out to force high shutter speeds I get overexposure in bright sunlight.
camera: SD800
I have read the FAQ which states:
The final shutter speed will be the product of "Value factor" times the "Override shutter speed value".
http://chdk.wikia.com/wiki/CHDK_firmware_usage/AllBest#Override_shutter_speed_value
Is there a page that puts this into "layman's" terms?
Hi sf_photo,
the Canon firmware swings in the ND filter in brigth light conditions, e.g. in direct sunlight (that's the equivalence to the highest F-stop number, e.g. F/8.0). Then it calculates the exposure time with this self-choosen ND filter state - if you set the ND filter to OUT, the original Canon firmware don't know this, the calculated exposure setting is wrong & your shots will be overexposed.
You should also override the exposure with CHDK or you can compensate the exposure time manually from the Canon menu.
2nd Question:
"Value factor" OFF disables the CHDK shutter speed override, to enable it set it to 1 (maybe on your camera there are only 2 possible settings, OFF and 1).
The "Override shutter speed" is a value in seconds (64s in the screenshot), multiplicate it with the "Value factor" (set it to 1) and you'll get your CHDK shutter speed...
[64 ] * [1 ] --> 64s shutter speed
[1 ] * [1 ] --> 1s shutter speed
[1/4 ] * [1 ] --> 1/4s shutter speed
[1/100k] * [1 ] --> 1/100.000s shutter speed
