New member question: Auto ISO

[KeithM]

I have been using a Canon 20d for several years and have just moved to the 5diii. One of the new features is auto ISO. With the 20d you fix the ISO, choose Av or TV and the camera adjusts the aperture/shutter speed to create the EV. With auto ISO, there is an additional 'degree of freedom'. If, say, I choose an Av setting how will the camera respond to low light - higher ISO or slower shutter speed? Thanks for any feedback.

[NorthernFocus]

You should be able to customize it to set a floor to ss. If EV still needs to go lower when that ss is reached then auto ISO will take over. I'm a Nikon shooter but per my understanding that other brand works the same way. Some other user of that other brand will have to point to you exactly where to set the customization feature. With Nikon it is logically under the auto ISO configuration setting

[jcuknz]

I never use auto ISO becuase of the serious problem that in poor light it will choose a high ISO which will result in excessive noise spoiling the picture ... but I do watch my shutter spped in those circumstnces and take precautions to keep the camera steady for the longer shutter speed the camera picks. Occasionally I do use a high ISO but I know and choose that and not the camera. It is probably the one control I do not give to the camera since starting with digital. I could set the camera to select ISO within a given range but prefer to work the way I have done.

[KeithM]

Thanks for that Dan.

[KeithM]

thanks jcuknz and nimitzbenedicto. my learning curve just got steeper!
I guess I'll avoid auto iso. Thanks again for your help

[dje]

Keith with Auto ISO you can set the maximum ISO value to use. This safeguards against excessively high ISO's.

So what happens with Auto ISO is this

Where correct exposure corresponds to fast shutter speeds, the minimum ISO is used

For decreasing light, slower shutter speeds are used until the set value of minimum ss is reached at which point ISO starts to increase.

With continuing reduction in light, when the set value of max ISO is reached, shutter speed starts to decrease again.

Dave

[Panama Hat & Camera]

Keith,
You have a great camera and I think you shouldn't discard completely the use of auto ISO, because it can be useful in some conditions. You should limit the highest value of iSO you want to use. According the DxOMark (http://www.dxomark.com/index.php/Cam...Sensor-Ratings), you can go until ISO 2293 with good results (set the max ISO in the camera to 2000).
Antonio.

[Colin Southern]

I guess I'll avoid auto iso. Thanks again for your help

In rapidly changing light conditions, Auto-ISO is your friend.

I'll give you a real-world example; of recent I was photographing a funeral - lighting was all over the place, and flash wasn't allowed. I've only got 3 variables to play with - shutterspeed, aperture, and ISO.

* below a certain shutterspeed (even with IS), I'm going to risk camera shake, and also risk subject motion

* if I open the aperture excessively, I'll have DoF issues

* if the ISO goes high, I may or may not get visible noise (depending on the dynamic range of the scene, and how hard I have to crop the image).

Which variable damages an image the least - Camera shake / subject motion or Lack of DoF or High ISO noise? (or put another way, if you're going to restrict the camera's high ISO limit - with no other options - which of the other variables are you going to change to balance the exposure)? If you have to choose between the three then, generally, High-ISO noise is by far the lesser of the 3 evils (and can be treated the most successfully in post-production).

I had the camera on Auto-ISO the whole time - AV mode, with my preferred minimum shutterspeed set.

https://www.facebook.com/ColinJ.Sout...5691996&type=3

[KeithM]

Thanks for your replies. They are all very helpful. I have a much better understanding now.

Keith

[Gaab]

another point is that the higher ISO on your 5DIII will be a lot more usable that the same ISO on your 20D.

I just upgraded from a 600D to a 6D and have been amazed at the pictures I'm getting on ISO's my 600D would have cried at.

I just set a max ISO ceiling in the options and for general walk around shooting leave it on auto. For landscape shots I set it all manually.

[pnodrog]

another point is that the higher ISO on your 5DIII will be a lot more usable that the same ISO on your 20D.

I just upgraded from a 600D to a 6D and have been amazed at the pictures I'm getting on ISO's my 600D would have cried at.

I just set a max ISO ceiling in the options and for general walk around shooting leave it on auto. For landscape shots I set it all manually.

Like you Gary I have upgraded, for me a Nikon D200 to D800 and the improvement in dynamic range and usable ISO is liberating. In the past I would not have contemplated Auto ISO but now in low light situations I let it do its thing up to ISO 3200. For landscapes I have always used aperture priority but now I have programmed the rear selection dial to be a quick manual ISO select.

[Manfred M]

I have no use for auto-ISO in my workflow. I always set my ISO manually (at as low a value as I can get away with); decide whether I and shooting for DoF (aperture priority) or motion (shutter priority) look to see if I am with an acceptable shooting range for the lens I am using and then shoot.

I do shoot by locking down one variable at a time; too many variables moving about at the same time is just too much for my old head and I can't keep track of things if I am not using a systematic approach.

[Colin Southern]

I have no use for auto-ISO in my workflow. I always set my ISO manually (at as low a value as I can get away with); decide whether I and shooting for DoF (aperture priority) or motion (shutter priority) look to see if I am with an acceptable shooting range for the lens I am using and then shoot.

I'm the same - mostly, but in situations where the light is swinging wildly, then auto-ISO gives the best of both worlds in that you choose your aperture - you choose your minimum acceptable shutterspeed - and the automation then gives you the lowest ISO to balance the exposure. More time shooting and less time manually selecting what would probably be the same settings anyway.

[dubaiphil]

Well it all depends on what you're shooting. Not knowing the setup on a 5D III, I would presume that you can create custom 'banks', as in the D700/800/3/4.

I have a custom bank set up for flash, for tripod work and for hand held in variable light (2 versions with different minimum shutter speeds and auto ISO). Then it's a very quick and easy shift between settings when required.

If I'm shooting in a fast paced environment I'd rather grab the shot than miss it from adjusting settings, ISO, etc. As long as you've found your comfort zone in terms of acceptable noise levels (6400 should be OK) then you're good to go.

[Colin Southern]

As long as you've found your comfort zone in terms of acceptable noise levels (6400 should be OK) then you're good to go.

People often talk about maximum ISO levels, but to me, it's a moot point. If you need to take a shot - you can't use a wider aperture (perhaps due to DoF considerations or you may already be at the lenses widest aperture) - you're already at your lowest shutterspeed, then noise or no noise, what other options do you have? (assuming you can't use flash or manipulate the scene in other ways).

[dubaiphil]

Well in this day and age people pixel and noise peep a lot, without necessarily seeing printed output. I'm happy at up to ISO4000, and 6400 at a pinch if I'm properly exposing the image and processing as I normally do. That's on a D700 - I've reviewed and tested a D800 and if you're not printing at really large sizes, 6400 should be more than comfortable enough. Converting to B&W helps as you get rid of any colour infidelity issues. The only headache I get at high ISO's are banding issues in dark areas of an image where there are bright light sources present.

The only other option - slow the shutter, hold your breath and squeeze gently. It has to be pretty dark for f2, 1/30th, ISO6400 though. Time to break out the D3S/D4 and crank up the shutter speed...!

[Colin Southern]

Well in this day and age people pixel and noise peep a lot, without necessarily seeing printed output. I'm happy at up to ISO4000, and 6400 at a pinch if I'm properly exposing the image and processing as I normally do. That's on a D700 - I've reviewed and tested a D800 and if you're not printing at really large sizes, 6400 should be more than comfortable enough. Converting to B&W helps as you get rid of any colour infidelity issues. The only headache I get at high ISO's are banding issues in dark areas of an image where there are bright light sources present.

The only other option - slow the shutter, hold your breath and squeeze gently. It has to be pretty dark for f2, 1/30th, ISO6400 though. Time to break out the D3S/D4 and crank up the shutter speed...!

If one can use a faster lens or a slower shutterspeed then they're of course free to do that anyway, but both of those things also come with potential side-effects (lack of DoF, potential camera shake, potential subject motion) that generally are less of a punishment that high ISO noise (ie little point in having a photo with acceptable noise, but blurred due to one of the 3 things mentioned above) (or no photo at all) - so they really have to make the call as to what they consider the best course of action at the time.

If someone is sizing up a shot that they can take or leave then fine - their call - but in cases where "failure is not an option" (eg photographing a funeral that I did a few months ago) I'm sure everyone would rather have the noise over shaky / blurry images, or no images at all. In reality the camera choose to use up to 10,000 ISO, and the images were "fit for purpose".

[Black Pearl]

I'm 100% with Colin on this, if you need (want) to take a shot and have ran out of other option then there is nothing wrong with using high ISO's. Using a high ISO does not mean you are going to get a noisy image. If shot correctly, used sensibly and you don't pixel peep there is almost no limit to how high you can push the camera.

[Manfred M]

I'm 100% with Colin on this, if you need (want) to take a shot and have ran out of other option then there is nothing wrong with using high ISO's. Using a high ISO does not mean you are going to get a noisy image. If shot correctly, used sensibly and you don't pixel peep there is almost no limit to how high you can push the camera.

Like anything else in photography, it is important to understand the tradeoffs you are making and these have to be taken in context with the specific conditions one is shooting under.

Higher ISO also means lower dynamic range, lower tonal range and lower colour sensitivity on top of the off discussed higher noise.

Are these tradeoffs worth it? As always, that depends on the shooter. More often than not, the answer will be yes, but sometimes the answer is to add more light.

[Colin Southern]

More often than not, the answer will be yes, but sometimes the answer is to add more light.

Yes - but I'm talking about situations where you CAN'T add more light. In my case I'd have loved to setup a couple of studio strobes inside the church, with on-camera for fill - but it just wasn't allowed (for obvious reasons).