How bad is it to use Auto ISO?

Do we really need to devolve yet another thread into a battle over the validity of auto ISO?

Again, learn your meter and metering modes and there is absolutely no downside to using auto ISO. Go flip through my flickr page, I shoot probably 90% in auto ISO and usually only have to correct within a 1/3 of a stop (if at all) in post.

birderman wrote in post #17672239
Surely if you using Auto ISO in M mode then you are not actually shooting in Manual mode but Auto Iso mode as the camera will try and AUTOMATICALLY compensate for exposure errors by adjusting the ISO. IMHO Manual mode should mean everything is adjusted and controlled by the operator.

Yes, strictly speaking, this is right. We talk about an exposure triangle with aperture, time, and ISO at the apexes. So it would make sense for the Canon mode dial to reflect this, and show an ISO position as well as Av and Tv. But having an auto ISO capability under M is a useful kludge.

On my 7D2, exposure compensation in auto ISO mode is easily done using the Q button. Not sure about the 550D, but I'm sure there is a way to do it with it as well.

I use it in the same situations outlines, where I know I need a certain shutter speed, and a specific aperture, but have various lighting within reason in the same area - Like an unevenly lit track or arena. Camera does a great job, and as I shoot raw, then as long as it is in the ball park, I have something usable.

This thread reminds me of the one about shortcuts. Its very title--"How bad is it . . ."--implies that using auto ISO is shameful and anyone who relies on auto ISO deserves criticism on account of laziness or something. Ineptitude? Lack of pioneer spirit? Some undescribed character defect?

Mastering your tools and knowing how to function independently of external aids are good things, but we have these advanced high-tech cameras, why not take advantage of their features when it suits the task at hand? Most of us don't make our own shoes anymore, either.

Both the new Canon 7D MkII and the current 1DX have exposure compensation in auto ISO.

Many Canon cameras including the 70D and the 5D Mk III have a mode where you can set a minimum shutter speed in AP mode. Problem is, the fastest speed is only 1/250 (or 1/200.). That is just too slow to be usable in most action type sports. I believe the 1DX has a faster minimum shudder speed but it is hard to justify that expense if you expect little or no ROA from an investment of that size.

birderman wrote in post #17672239
...such as the EOS 550D. ...what happens if in M mode one adjusts the settings for the needle to be off-centre by the desire EC amount, will the Auto ISO remember this and adjust accordingly on each subsequent shot ?

Archibald wrote in post #17672252
...Not sure about the 550D, but I'm sure there is a way to do it with it as well.

On the 550D and other Rebel cameras it is impossible to bias the meter in M with Auto-ISO set. It will always be centered unless the ISO bottoms or tops out.

rrblint wrote in post #17672330
On the 550D and other Rebel cameras it is impossible to bias the meter in M with Auto-ISO set. It will always be centered unless the ISO bottoms or tops out.

Yes you are right. (I stand corrected.)

I would use AV mode and to allow the camera to control the shutter speed as long as I know that the shutter speed won't drop below 1/400s. Go meter some dark area of the location and to set the proper ISO that way. Considering you aren't going anywhere other than watching whales during day light, you won't be using any high ISO setting like 1600 or 3200. I rarely use auto ISO fyi.

Being as I have never been to this particular location before I'll just have to adjust on the fly. Which is basically what I would do I any situation anyway.

Since I started in photography a few years ago I have always set my ISO manually. Usually, in Av as I said before.

I've never really experimented with using the auto ISO. I was under the impression that the camera may needlessly use a much higher ISO in auto then is necessary.

If it comes out to be a sunny day then it shouldn't be much of an issue. But I'm not sure how much the fog will become a factor in Monterey Bay.

Either way I'll have the shots in a few days as I'm already out here on the west coast, and I'll let everyone know how it went.

Mr_ipsum wrote in post #17673083
Being as I have never been to this particular location before I'll just have to adjust on the fly. Which is basically what I would do I any situation anyway.

Since I started in photography a few years ago I have always set my ISO manually. Usually, in Av as I said before.

I've never really experimented with using the auto ISO. I was under the impression that the camera may needlessly use a much higher ISO in auto then is necessary.

If it comes out to be a sunny day then it shouldn't be much of an issue. But I'm not sure how much the fog will become a factor in Monterey Bay.

Either way I'll have the shots in a few days as I'm already out here on the west coast, and I'll let everyone know how it went.

If the camera picks a higher ISO than you would, but without blowing highlights, then that would just amount to exposing to the right, which would give you a pic with better IQ, I believe.

Mr_ipsum wrote in post #17673083
Being as I have never been to this particular location before I'll just have to adjust on the fly. Which is basically what I would do I any situation anyway.

Since I started in photography a few years ago I have always set my ISO manually. Usually, in Av as I said before.

I've never really experimented with using the auto ISO. I was under the impression that the camera may needlessly use a much higher ISO in auto then is necessary.

If it comes out to be a sunny day then it shouldn't be much of an issue. But I'm not sure how much the fog will become a factor in Monterey Bay.

Either way I'll have the shots in a few days as I'm already out here on the west coast, and I'll let everyone know how it went.

I'm not sure I understand the concern... if you wouldn't select a higher ISO, what would you select? A lower shutter-speed?

personally, I'll take a grainy photo over a blurry one.

Take some test pictures now of dark objects and light objects using your anticipated shutter speed. See if you have any issues. What camera are you shooting.
I recall having a drastically underexposer issue in a few cases. Still haven't figured out why.

I mean a higher ISO than would be necessary for the given situation.

Mr_ipsum wrote in post #17673083
I've never really experimented with using the auto ISO. I was under the impression that the camera may needlessly use a much higher ISO in auto then is necessary.

In my experience, if you're shooting in AV, the camera normally adjusts the shutter speed before it adjusts the ISO...which normally turns out being unhelpful since I normally shoot events with moving subjects. If you're doing landscapes...I'd imagine it wouldn't be that big a deal for a slower shutter speed.

I normally choose my aperture and shutter speed and leave ISO to auto if lighting conditions are inconsistent. If lighting is consistent, I'll take a test shot with auto ISO and dial it in from there.

Mr_ipsum wrote in post #17673419
I mean a higher ISO than would be necessary for the given situation.

There are actually two ISOs, which people often think of as one. One is the ISO exposure index, which is basically the inverse of exposure on the sensor in an area that is going to become middle gray in the scene. This has nothing directly to do with the ISO setting on the camera, and is not fixed at the time of exposure! It is up to you to decide what becomes middle gray in the final image, and you can decide after the exposure - cameras with RAW and high-DR ISO settings allow the most latitude.

The other ISO is the setting on the camera, and this works the opposite of how many people would think. You get the least noise in your image of any given ISO exposure index with the highest ISO setting; the only reason higher-ISO-setting captures are often noisier is because the metering at that ISO causes a lower absolute exposure, or ISO exposure index. The higher ISO settings in the camera actually add the least noise to the signal. That is why they are considered to have a greater "sensitivity" - the only problem with them is that they might clip desired highlights, or don't offer any less absolute noise above a certain ISO setting.

So, if you are using auto-ISO "M" mode, and the ISO goes higher than expected, for the RAW shooter there is no danger except that highlight details might be clipped.