Ok, I installed the firmware and shot about 300 frames under conditions similar to the original problem case, and I don't see any banding nor blotchy underexposure as in the first case. Time will tell.
Pondria wrote:
I agree.
It looks like only 100, 200, 400, 800 are the legit (?) ISOs.
Not only that, it also looks like, you can just take shots @ ISO 800 and use the EV compensation of the raw converter to get the high ISO results.
Pondria,
From your graphy, it seems like it is an exponential function from ISO100, 200, 400 & 800. Starting at ISO800, it becomes a linear function. Interesting.
No, you cannot use EV compensation in post processing to get the high ISO results, as higher ISO does allow to use higher shutter speed and/or smaller aperture when you take the shot.
stanj wrote:
Ok, I installed the firmware and shot about 300 frames under conditions similar to the original problem case, and I don't see any banding nor blotchy underexposure as in the first case. Time will tell.
Stan,
I am wondering if the banding you saw was one of the weird stuffs that only happens rarely
slau wrote:
No, you cannot use EV compensation in post processing to get the high ISO results, as higher ISO does allow to use higher shutter speed and/or smaller aperture when you take the shot.
Of course you can. Dial in exposure compensation of -1, -2 and you're done. Shutter speed gets faster.
Pondria wrote:
We actually found something interesting here last year with 1Ds2 and 5D.
It seems that;
The full stop ISOs ( ISO 100, 200, 400, 800 ) are implemented with HW gain . But the ones in-between and 50/1600/3200 are implemented with SW. The full stop ISO has lower noise than the in-between ones. i.e, ISO 200 is cleaner than ISO 125 and 160. You can verify it by taking the shot with lens cap on and Manual mode. Check the with of the noise in the histogram. This betrayed those who trust that ISO 320 would be cleaner than ISO 400.
I tried the same as you, as you described, but my 40D shows almost no visible noise at all ISO's (except 3200). Only 1 or 2 dots are visible at actual size. Eg: at ISO 640 there's only 1 blue spec of 2-3 pixels visible in the upper left corner (might be a sensor defect like a TFT screen ), and at ISO 800 the same spec is there. Nothing more, nothing less...
Which software did you use to check the noise in the histogram? I find the histogram on the 40D quite limited for this test. In the Canon Zoombrowser software I do notice some difference, but it's not what you concluded. Eg: ISO 200 has a small bar, but ISO 250 hasn't. ISO 320 a bit more than 200, and ISO 400-500-640-800 again no bar.
Maybe Canon has solved this issue on the 40D?
Or I'm doing something wrong...
Pondria, do you know if the intermediate ISO problem occurs on 1D mkIIn?
I like having 1/3 stop control for aperture and shutter speed. It doesn't look you can limit ISO to full stop increments with custom function unless you also want to limit aperture and shutter speed to full stops.
Also curious to know more details of the test procedure. Presumably the manual exposure would have to be longish (1 sec?) to measure the noise on the histogram.
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