You make nice photos so i'd like to ask for your input about something you said.
... I shoot Aperture priority 99% of the time and rely very heavily on ISO adjustment (never use auto ISO) and exposure compensation.
You use A mode almost exclusively and you are obviously happy to control image lightness by using the EC setting. So why don't you use Auto ISO? What do you feel you would be giving up?
I guess first of all, that's just the way things worked out naturally for me and I haven't changed.
That's how many of us get to where we are.
I probably should have said, " I never use auto ISO". The way I worded it some might think I meant you should never use auto ISO. Everyone has their own way of doing things.
Not to worry. I actually interpreted what you said in the way you meant it, not as a directive to others.
I'm asking because I see a lot of good photographers saying they don't use Auto-ISO. I'm trying to understand why that is, and more importantly, whether there are any actual advantages in image quality to be had by always avoiding auto-ISO, or whether it is merely a matter of good photographers are generally experienced photographers, and many experienced photographers learned on film where there was no Auto-ISO.
2 reasons really. First off, I've seen far too many posts where the user stated " the camera picked too high an ISO'.
Yeah, I've seen a lot of those posts too. I just don't understand them. Surely the camera used no higher an ISO than it needed to get the result the photographer specified.
What does "too high an ISO" mean? "Too high" for what?
One possibility, and the most obvious one since the ISO setting is essentially a lightness control, is that "too high" an ISO is one which gives too light an image. That shouldn't apply to you since you already know to control lightness using the EC setting. If the image is too light, it is because the photographer set EC too high, not because of Auto-ISO.
The other obvious explanation is that the ISO is too high to avoid unwanted noise. But this doesn't make any sense either. Sometimes this claim is a result of the widespread myth that high ISO causes higher noise. High ISO doesn't cause the noise. The noise is there because the exposure is too low, and the camera set the ISO higher because the exposure was too low to make the image light enough without a higher ISO. So the real problem is too low an exposure, not too high an ISO, and the exposure is too low because the photographer didn't set the aperture wide enough or the shutter slow enough for the available light. If the photographer cannot set the aperture wider (because it is already wide open or because he needs some DOF) and is using as slow a shutter as he dares, then the noise is unavoidable. Don't blame the noise on Auto-ISO.
The camera is just following instructions. It is in an autoexposure mode because the photographer put it there. That means the photographer is trusting the camera to select the target image lightness, as modified by the EC setting. The photographer was responsible for the EC setting and at least one of aperture and shutter.
For the sake of this discussion, let's assume we're talking about bird photography. If I have to let the camera pick something I'd rather it was the shutter speed.
Why? Isn't the minimum acceptable shutter speed, as determined by the speed of wing flap and amount of sensor covered by the moving wing, the most important judgement the photographer can apply to settings for BIF?
I know the shutter speed range I need to be in with any given scene depending on what I'm shooting
Right!
and I adjust my ISO accordingly
That seems rather indirect. Why not adjust your shutter speed itself? This will allow you to be more precise.
always trying to keep it as low as possible.
Is there any chance you are sometimes maybe a stop too high on ISO? Or to put it another way, if you decide that your minimum acceptable shutter speed is 1/1250, do you ever find that after adjusting ISO to be sure that you can get 1/1250 you actually get 1/2500? What about getting 1/1500. 1/1600 or 1/2000? I suppose you do sometimes set ISO higher than needed because you talk below about getting 1/4000 instead of 1/1000. So using your approach sometimes gives you more noise than you need to have.
We're also assuming here we know what aperture we want to be at.
Sure. Would you say you adjust aperture more frequently than you adjust ISO? In your examples you talk about adjusting ISO and EC more than you talk about adjusting aperture, and, of course since you are in A mode, you don't adjust shutter yourself at all. In fact you say "I am adjusting ISO and EC constantly", but don't much mention adjusting aperture.
If I'm watching a heron fishing for instance, I adjust settings assuming I need a shutter speed high enough to catch a strike or a flyoff. If the bird looks like it's not going anywhere and I feel my ISO's a little too high I'll lower it for a static shot and then raise it again if I'm waiting for the bird to take off. Keep in mind, all these adjustments are made with one finger and my thumb without taking my eye from the viewfinder. Also, I shoot 99% of the time from a tripod with Wimberly head so it's really easy to adjust everything on the fly.
If it sounds like a lot of fiddling with adjustments it is.
Yes but possibly not excessive fiddling. There is a lot of fiddling because you need to make these adjustments. Comes with the subject matter, and the selected mode.
I am adjusting ISO and EC constantly. As far as EC goes; if I'm focused on a wading bird with a dark background behind it I may be at 0 EC or - 03. If the bird takes off I'll spin that dial to the right an dial in positive EC while tracking the bird in the viewfinder. It only takes a split second and just from practice you can look at the brightness of the sky and the color of the bird and know pretty accurately how high to go.
Sounds right to me.
And as long as I know I'm at a safe minimum shutter speed to begin with, who cares if it goes from 1/1000 to 1/4000 ? A higher shutter speed never hurt a BIF image. (panning aside).
Really? An image taken at 1/4000 has half the SNR of the image taken at 1/1000. A lot of people can see the two stop difference in noise, unless they are looking at small prints.
The second reason is I see no need to.
Yeah. Let's explore that later.
I always get a bit of a laugh from posters who claim " I always shoot Manual... with AUTO ISO" Where I come from, that's just another auto setting.
You are right of course. It
is just another auto setting. It is an Autoexposure mode, just as P, A or S (regardless of whether Auto ISO is enabled) are Autoexposure modes.
Chances are this only makes sense to me
Don't underrate yourself. I expect this makes sense to a lot of folks.
but maybe it will help someone
That's why we are here.
and thanks for the compliment
Your results deserved it.
I'm sure there are those who see no sense in any of this and that's fine, but I've read so many other methods and even tried some but always go back to this.
It sounds to me like you are choosing to use an autoexposure mode and are controlling three of four things yourself, and letting the camera control the fourth. You control aperture directly. You control lightness by adjusting EC, which is the proper way to control lightness in an autoexposure mode. Unless you are constantly chimping, this is a little bit imprecise - you are making an educated guess. Finally you control shutter indirectly, and also a little bit imprecisely, by adjusting ISO setting. You don't care much about the specific ISO setting and are not trying to set a specific shutter. Rather you are just trying to be sure the shutter is at or above a specified minimum. You are not worried about having a faster shutter than the minimum required nor about the possible range of noisiness that comes from this approach. As a result, you may err on the side of caution and set the ISO a little bit higher than it really needs to be in some shots. We can safely say that some of your images are noisier than they need to be.
Let's explore the practical differences between your approach and using A mode with Auto-ISO. This too is an autoexposure mode, and using it you set three things yourself and let the camera control the rest. You set the aperture directly. You control image lightness by adjusting EC. So far, this is just the same as A mode without Auto ISO. The differences are that you set the minimum shutter speed as a parameter of the Auto-ISO settings and then don't have to constantly fiddle with ISO. There are three advantages of this approach over A mode without Auto-ISO:
- Your fiddling has been cut in half. yuo now only have to adjust EC, not EC and ISO.
- Instead of relying on your manual ISO setting to be high enough to get a fast enough shutter, with Auto-ISO you have a guarantee that the shutter will never fall below the minimum you specify.
- And the camera will never set the ISO higher than what you actually need to get the minimum shutter, but will automatically set the shutter and ISO to give the lightness you specified with the EC setting. It will only ever raise ISO above base if it has already slowed the shutter to the minimum you specified. Noise will never be higher than it needs to be.
The net result is that you get the same control over aperture and lightness, and better control over shutter and noise, while having to do less work from shot to shot. For at least some people this is a reason to use Auto-ISO.
There is at least one disadvantage of using A mode with Auto-ISO compared to without Auto-ISO. If you sometimes need to change your minimum shutter speed in a hurry this is harder to do with Auto-ISO. For that situation there is a different mode: M mode with Auto-ISO. Let's explore the practical differences between your approach and using M mode with Auto-ISO. But before we look at the differences, let's look at the similarities. This too is an autoexposure mode, and using it you set three things yourself and let the camera control the fourth. You set the aperture directly. You control image lightness by adjusting EC. Again just the same as your approach. The differences are that you set shutter directly and precisely, while letting the camera adjust ISO. The camera never sets ISO higher than it needs to be for the aperture, shutter and EC you have selected. Instead of indirectly and imprecisely controlling the shutter by adjusting ISO, you control the shutter by controlling the shutter. This lets you set the shutter to what you decide is the necessary minimum speed, and you can easily change that from shot to shot. Not only is your shutter control more precise, you will never have more noise than you need to have.
Again, using Auto-ISO gives you the same control over aperture and lightness, while giving you more precise direct control over shutter and guaranteeing no more noise than is needed for your aperture and shutter choices. The things you control directly are the things you care most about.
So again, I'll ask: what do you think you would be giving up by using Auto-ISO?
