I was told it’s not good to use auto ISO. I responded that I will try to set my ISO manually in P,A,S,M Mode’s but I think I got issues. I keep seeing it in auto ISO, it’s getting me the shot even though there is some noise. Was also advised that it’s better to get the shot then nothing.

If I can break this habit what is a good workaround to setting the ISO. What are some best practices?


7 Answers 7


It’s getting me the shot even though there is some noise

This is the point. If your priority is getting the shot, why not. But if your priority is getting a printable photo (which is what many people are after) then you have to make sure that you won't be using an ISO setting that makes your camera produce more noise that you can post-process (given your post-processing utilities, and your skills...).

This said, usually you know in advance in what kind of light you are shooting (daylight, indoors, at night...), and have an inkling of the ISO-to-noise characteristics of your camera so you know what range of ISO you need. And you can also choose to use a fast lens, even if you have to forego other capabilities (zooming...). Photography is the science of compromises. Normally, my camera (70D) is set to ISO800 and I use mostly Aperture priority. If the resulting speed is vastly over my needs I reduce the ISO, and if is lower than I need I increase the ISO.

If your 80D is like my 70D, if you set the ISO to some value (something else than "A") then it is fixed an no longer automatic. You can also reduce than range used by Auto-ISO in the camera settings (Menu 3 > ISO Speed settings)

  • 1
    Sometimes you don't have time to fiddle with settings before you take the shot, and I have to say that auto ISO makes sure that the telephoto pictures of helicopters that fly by my house with only a few seconds of warning (hearing them coming) are both bright enough and not blurry.
    – Michael
    Aug 27, 2021 at 21:16

I was told it’s not good to use auto ISO

If unqualified, whoever told you that is a fool. Auto ISO is a tool, and as with any other tool it can be used well and it can be used badly.

Instead try to learn when auto ISO will do as well (or better) than setting it manually, and when you need to override the camera's decision.


What are some best practices?

This is all opinion... or, at best, situational. My personal feeling is that it is best to learn exposure in full manual mode and learn/understand the exposure triangle. The basic concepts are really not that hard if you just jump in and apply it.

Then you can use automation to help you achieve what you would have done manually, only much faster/smarter.

FWIW, I shoot 95% in aperture priority with auto ISO.


In my opinion, there is only one best practice. Know your stuff, know your gear.

In this case, define what is the maximum iso you are willing to use, the maximum noise you are willing to accept in most cases.

Prepare a small studio scene, on an interior so the light does not change too much during your session. A Still life scene with some bright colors and some black elements. Black cloth, your camera case.

Use a tripod and make some controlled tests. Define the aperture, let's say f4, and set your camera to Aperture priority.

Now take a series of photos scrolling to all your available ISO. Turn off the auto denoise on your camera.

  • ISO 100
  • ISO 200
  • Your max ISO

Now compare and study the images on a good monitor. If you shoot RAW you can make additional tests on how the denoiser of your software work.

Based on that you now know if you set your max preferred ISO beforehand on an interior scene.

You also need to do these tests handheld with your focal lengths and know how much camera shake you can control.

But yes, It is easier to remove noise than blur due to camera shake or slow shutter speed.


What are some best practices?

Practice is the only best practice. Make a picture, look at it, decide what works and what doesn't. Do that a lot.

If auto-ISO works for you, use it unless it doesn't. Then try something else.

What matters is the picture not the camera settings.


Of the three variables that control exposure, ISO is the one with the least creative effect. Aperture directly influences the depth of field. Shutter speed controls the amount of motion blur. ISO on the other hand "just" generates noise if too high.

So giving your camera automatic control over ISO doesn't limit your creativity, and helps you focus on more important settings. The advice "don't use auto-ISO" usually is due to the fact that in low light situations, the camera might choose a ridiculously high ISO values (causing excessive noise) to make up for possibly poor speed and aperture choices without you noticing it.

In my opinion, there are better tools than disabling auto-ISO completely to prevent excessive noise. As other answers already state, you can set an upper limit for auto-ISO on most cameras. This means you can set a maximum allowed level of noise, but you camera is able to match ISO automatically if you specified your preferences on speed and aperture. There is no harm in using a lower ISO than the "maximum acceptable noise level ISO" you specified.

Another way to handle ISO setting offered by most cameras is not setting a hard limit on ISO, but just display a warning if noise will be high. This allows you to get a one-click choice in low-light situations: When you half-push the shutter button, you get a warning that the picture will be noisy due to high ISO. You can decide in that second whether you continue with the shot and tolerate the noise, or you think "oops, I forgot that I chose 1/1000 shutter speed for the outside shot 10 minutes ago, let me fix that".

Or, on a higher level: If you shoot "P" anyways and let the camera guess appropriate settings, turn on auto-ISO to give the camera more freedom to choose an appropriate point on the exposure triangle. Choosing P is a strong indicator that your preference is clearly on "getting a shot done", not on fine control over the exposure details. On the other hand, if you shoot primarily M, you might want to lock in or limit ISO too, to get full control over the exposure yourself. There are basically two ways to use M, I consider both valid: Either you choose ISO by hand, which will yield a user-defined exposure without any camera heuristics interfering with you, or you use auto-ISO to have the camera pick a adequate ISO for "correct" exposure. In the latter case, use the exposure compensation setting to adjust exposure in case the camera over- or underexposes the image compared to your expectations or requirements.


Personal experience with shooting birds for quite a while, but applies to basically fast movement vs time to play with the buttons:

  • see the (flight) pattern the birds have
  • match the shutter speed so the photo does not look blurry
  • match the f-stop so I get the sharpness / bokeh I want

Afterwards, if the light conditions are changing by:

  • quick increase/decrease by clouds passing through the sun
  • me moving with the lens fast thus changing the side-/back-lighting
  • different colors in the background

I choose whether I do or do not enable auto ISO. The reasoning for that is - I want to get the shot. Once I get a good enough shot, it's most likely sharp enough so I can apply various de-noising and contrast amplifying techniques so it loses a bit of the sharpness while still being okay (for me) to put it to print.

If I don't turn auto ISO on, I'm forced to play with shutter or f-stops, neither of which I might actually want to do, OR I need to adjust ISO manually which is at least on my camera annoying as hell when I want to shoot a bird flying by over the water or similar fast actions/movements.

Of course, auto ISO can be also annoying i.e. it'll try to balance to "zero" i.e. not have your photo over-, nor underexposed, but it's still a machine and in some cases having it -1 or +1 stop is actually what you want and auto ISO will fight you (unless you can adjust the exposure target to not be "zero"; check the manual).

If you think you have time to play with the light (i.e. probably not action scenes) - setting ISO manually might be better to be more precise. However if you are flexible with the de-noising and you want to shoot actions, auto ISO will help you.

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