[EDIT: I just got a reply from Canon that this is known and that it will be addressed in a firmare update soon.]
Ok, I thought this may be a useful feature. So I set the camera to f2 being the widest aperture, set Tv to 1/100s, and turned on SS via ISO. Then I proceeded to shoot my daughter, at 5fps, just for fun.
For most of the images the camera chose ISO 1600. Fine. Then there was this sequence of three images, all taken back to back, within one second as part of a burst. The camera switched from 1250 (the last image before this sequence) to 1000 to 1250 to 1600. The result was ... well, astonishing. I am including the 100% crops of the "Small" in-camera JPGs, but when you look at the raws the problem is there, too. The first image (when the sensor switched from 1250 to 1000) has severe banding, the 2nd one is at 1250 again and looks fine (for how pathetic the light was), and the 3rd 1600 shot is ... well, black.
Looks like the sensor doesn't like being cycled in sensitivity very rapidly. If that's the case, why does the camera allow this? Personally I'd rather have an improperly exposed image than this.
The pictures leading to this sequence, and those following, were acceptable as would be expected for the worse-than-horrible light (similar to the middle image). However, the stripes in the first, and the ... well, total darkness in the last are unexpected and indicative of a failure of some sort.
i haven't tried this feature on my 1D3 to see if it works as advertised. coming from using the original 1Ds for so many years, i always thought ISO 1600 was so clean on the 1Ds2 and 1D3 that i never worry about cranking ISO up the old fashioned way.
the stripes almost make me think that the safety shift came from image processing rather than increased sensitivity in the sensor. it's weird.
Bummer. At least it's not a critical feature of the camera, although it should work as advertised. Hopefully it will be an easy firmware fix, and that'll be the end of it.
FAU4U wrote:
Thanks for the info on the ISO shift issue.
I will return CFn-1,8 from "3" back to "0"
until the Firmware is updated.
Actually, it would be interesting if you'd test your camera in that mode as Stan suggested, and see if you can confirm whether it's a widespread issue or not (though it sounds like it is).
Since we are at testing, note that you have to be in Centerweighed Average metering as otherwise the exposure will be locked in a burst (unless you have other fancy CFn set, I don't).
Looking back, why would one need this feature any way ? I wouldn't want my camera to slide the ISO behind my back We are not talking about an entry level DSLR here.
On the other hand, Canon got rid of seemingly useful features from 1D series. (1) A-DOF mode (2) 1/250 shutter speed floor in Av mode with flash.
I totally agree that DEP (not A-DEP as on the entry level cameras) was most useful. As was the sensible way of changing AF points with the rear dial, here since the 1v thru the mk2 cameras; now with the mk3 it's totally dumb. But I digress.
My reason for wanting this: When shooting indoors available light, with my fast primes, say I want ideally 1/100s shutter speed (or whatever). I also can pre-select f2 as being the max aperture the camera will use (if I feel like it, say for DOF). So I can go set it up like this, and set say ISO 400. For many shots, 1/100 at f2 may suffice. For others, just go ahead and change the ISO. With the 1Ds3 I feel comfortable all the way to 3200 (which it ironically never selects even if I have H enabled).
To me, it's just like the camera changing aperture or shutter speed "behind my back", except that sometimes having the aperture more-or-less fixed and having the same apply to shutter speed is useful. Ideally, I'd like to have SS do ISO and _then_ Tv/Av - it's possible that the camera will bump to 1600 and Tv 1/100 is impossible, then start dragging the shutter.
While I rarely use P mode, and rarely would use this SS setting as well, I totally see use for it - honestly, more than for the DEP on the mk1 cameras, and I used to love that feature
Now if I only could have my AF point selection back...
Pondria wrote:
Looking back, why would one need this feature any way ? I wouldn't want my camera to slide the ISO behind my back We are not talking about an entry level DSLR here.
On the other hand, Canon got rid of seemingly useful features from 1D series. (1) A-DOF mode (2) 1/250 shutter speed floor in Av mode with flash.
Oh, so in Av you don't like the camera setting the shutter speed etc? I think that this feature is very useful. I have lost count of the times that I've ended up shooting at a higher ISO than I need and this is a great way to ensure that on a busy shoot the best possible quality is (when it works of course) obtained.
OK, I'll accept that Auto-ISO is logically similar to Av or Tv mode. For given exposure, one of 3 parameters { Aperture, Shutter speed, ISO } can change while the other two are fixed.
It's just that I'm not used to Auto-ISO. In Av or Tv mode, I can anticipate the effect of the automatic changes. It is almost my second nature instinct. In Auto-ISO mode, what is changing are DR and Noise of the photo. And the effects are very camera-dependent. It would take sometime for me to get used to.
We are not talking about an entry level DSLR here.