I think The A450 have the iris! Because i have try to use the Fireworks mode in A450 CHDK shown Av:7.85 in the LCD display
when i have zoom to 17.6mm it show Av:13.55
and i saw inside the lens have some different
(I don't know how to tell maybe i try to take some pic when i back home)
(I have uploaded a picture using fireworks mode notice the F number in the EXIF)
Hmm...then...ND-filter is probably used in "Fireworks mode"
When you look at your sensor throught lenses, do you see moving iris or just ND filter covering and uncovering the sensor?
Just try to Put In/Out ND filter in "Extra Photo Operations" and you will see..
The F (Av) number is somehow enumerated from focal length and ND filter presence for A460.
And I believe this way it works also in A450.
F-numbers (all zoom steps) for A460 are:
ND-filter out: 2.8 3.2 3.5 3.5 4.0 4.5 5.0 5.8
ND-filter in : 8.0 9.0 10.0 10.0 11.0 13.0 16.0 18.0
Could you provide F-numbers for all zoom steps from EXIF in "Fireworks mode" (probably in range 8.0 to 16.0)
Another question is: Do you see CHDK shutter speed at the bottom of LCD display?
It should look this way:
1/60" F2.8or do you see
1/60" F?If you see '
?' then it needs to be fixed.
another question when i'm using the "Extra Photo Operations" Override some stting Like "ISO" shutter
the metering system haven't use the override setting. is it normal?
Hmm...this is probably correct behaviour.
The metering system of my A710IS also doesn't care about "ISO override"
Pavel