Auto ISO and Manual Mode?
This might be a dumb question, but if I am using Manual Mode, does it matter if I have my ISO setting set to auto or should I set it at a fixed amount? I was just thinking about what happens as the sun is rising or setting. I would think if the camera is constantly adjusting ISO it might mess with the manual settings I have dialed in. Thanks.
Hi Bryan- Implementation of auto-ISO differs between bodies. On the Canon 1DIV you can set manual exposure mode, set your SS and aperture, and set either a fixed ISO setting or Auto-ISO. In Auto-ISO, the ISO setting will vary depending on lighting conditions and what the camera meter says, and essentially gives you auto exposure mode with fixed SS and aperture. One thing I am not sure about is if you can dial in exposure compensation in manual exposure mode/Auto ISO. I'll check tonight.
The quick answer to your question is- yes it does matter.
Bryan,
Using Manual control allows you to make the decisions...why give it back to the camera using Auto-ISO?
Chas
Bryan, I find that I am using Auto-ISO quite frequently now with my 7D when I shoot BIF (especially in the early morning hours). It works fine in Manual mode. I was a purist before and was avoiding all-things auto, but find that it does a great job and helps me get proper exposure on a bird that flies rapidly from ground-level (dark BG) into the bright sky or if I'm shooting ground-level birds and another bird that I want suddenly flies overhead. I may be shooting at ISO 1600-3200 at ground level, but only need 200-400 overhead.
I was not coming from manual but from aperture priority. When I went to auto iso I liked that I could control ss and aperture.Originally Posted by Charles Glatzer
When you are using auto ISO, you are not using manual exposure mode. Period.
Just checked the 1DIV and with manual exposure mode and Auto-ISO set, you cannot dial in exposure compensation.
Ian- I'm surprised this works for you. BIF is a classic situation to switch to Manual exposure mode (no Auto-ISO) so that backgrounds of varying tonality do not affect the exposure of your subject. In Evaluative metering mode this will happen frequently unless the subject dominates the field of view, and after all, you are usually trying to expose the subject properly, not necessarily the BG. In spot-metering mode you may be able to get away with it if you can keep the spot over the subject, but even then you could be spot-metering on a dark part of the subject which might result in overexposure of subject highlights unless you dial in exposure compensation. Much better to set to manual exposure mode, set a shutter speed and aperture that exposes to the right but does not overexpose the highlights, and shoot away. This is a much simpler solution.
Thanks John for checking that out. I think auto ISO is a useful option for certain scenarios, but I think I am going to go back to setting a fixed ISO and working in Manual Mode.
I'm not sure that I agree with that, Peter. I was shooting dark shorebirds against a dark water background just after sunrise in Gilbert when an Osprey flew over me unexpectedly. I had been using Auto-ISO, Manual, 1/1600sec, f/5.6 and ISO of 3200. I swung up fast to catch the osprey and got this at auto ISO of 640. If I had been shooting manual ISO at 3200, it would have been grossly overexposed. I admit that it's not the best image, but I think you can see my point. I also admit that someone with skilled fingers and fast reaction times could have adjusted the ISO quickly, but I'm not that quick.
Canon 7D
Canon EF 400mm f/5.6L
Last edited by Ian Cassell; 04-20-2011 at 06:18 PM.
And, as he flew over, ISO stepped to ISO 1000
Auto-ISO + manual mode = shooting at 0 EV (as in no exposure compensation)?
I think that's true if the scene is "average" like a 18% grey card. Then again, it's true for any other auto-exposure mode as well in that scenario.
IMO, auto-ISO + "manual" mode is still an auto-exposure mode. Only that this time, instead of altering either the aperture (when in shutter priority mode) or the shutter speed (in aperture priority mode), the camera is altering the ISO to adjust to the scene.
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