resources for SLRsWhat does it means?
I mean if you find a formula or tool online, it might assume a different aspect ratio, because professional cameras like DSLRs are often different from what the CHDK cameras use.
Where I can found this list? Is CHDK provide function for get sensor aspect ration?
There is no function in CHDK that directly gives you the sensor aspect ratio.
You can get the current *image* aspect ratio from ASPECT_RATIO propcase: https://chdk.fandom.com/wiki/PropertyCase
but this doesn't exist (or isn't known) for propset 1, and the values might have different meanings between propsets.
You could get the sensor aspect ratio from raw dimensions at https://chdk.fandom.com/wiki/CameraFeatureTable
or from the CHDK source.
Or you could just not worry about it: The vast majority of CHDK cameras are 4:3. I believe the only 3:2 cameras are G7 X, EOS M3 and EOS M10
Some cameras have 16:9 screens, but I believe most (if not all?) still use 4:3 sensors.