When I’m going out with the camera, I want to make sure I get the best shots possible. This means taking away as many distractions from the camera as I can, but still retaining all the control I need to get those photos. Over the years I’ve learned that auto-ISO is your friend, and here are a few reasons why.
Before we go into the reasons why auto-ISO is great and one of your most useful settings, of course there are times when you need to take manual control of them. Just like any of your camera settings, you have a choice, and in certain (a minority of) circumstances you’ll need to set ISO manually.
1. You can set the parameters as you need.
Unlike older cameras, the automatic ISO function on newer cameras is much more sophisticated. You can set the minimum ISO (which I always set to the base ISO160).
You can set the highest possible ISO that the camera will use if it had to deviate from that, which I have 3 settings for; daytime with a high of ISO800, evening with a high of 3200 and darkness with a high of 12800 (presets 1, 2 and 3).
The third parameter you can set is the minimum shutter speed that the camera will drop below, and this I usually set to 1/125. (*Note: if the exposure around you means that the ISO needs to go above your dry highest ISO because it needs more light, and your aperture is at the widest you’ve set, then the shutter speed will decrease if it is not set manually on your camera).
2. The camera is faster and cleverer than me.
Cameras are not as stupid as some think they are. Your camera will always try and achieve the lowest ISO that you have set. The only time it will raise the ISO is if you suddenly start shooting and the light changes.
For general walk around photography, events and wildlife photography, auto-ISO is a no brainer. You’ll always get the shot exposed correctly, without any issues.
3. You’ll have more time to concentrate on the composition.
Photography should never be about worrying about your settings. The last thing you should be doing is fiddling and changing your settings when there’s a chance you’ll miss the shot. Having the camera take over your ISO is the simplest remedy and it just works.
4. You’ll stop having blurry images.
An image with a high ISO is far more preferable than a blurry image because your shutter speed was too slow. Don’t be afraid to use your auto-ISO for the situation you are in.
I recently seen a video where they set the auto-ISO settings to a max of the highest native ISO setting (12800 on the X-T3) and used that at all times, and thinking about it, it makes sense. I will myself be trying this from today.
5. There’s no need to be afraid of ISO these days.
If you’re afraid to use a higher ISO (6400+), then there’s a good chance you’re in the wrong mindset or just doing something wrong with your photography. Modern cameras handle ISO very well, and a little noise is perfectly fine.
The trouble we have is that too many photographers like to pixel-peep at 400% or more. This is NOT reality, and on top of this, the ones that pixel peep are the ones who only ever share their work online, where no one looks at your image for more than a second, and generally on a tiny phone screen.
Printing your images, and finishing off the process off taking photos, noise is hardly noticeable even if it looks a lot on your monitor, and when viewed at the correct viewing distance (ie, not looking at a print an inch from the paper), it is never an issue. Composition is far more important than a noise that others viewing your image will never care about.
If you’re that worried, there is plenty of software that will illuminate noise for you, but it’s honestly not an issue!
Conclusion
There’s been a huge problem in photography over the years, mostly social media and YouTube led, where photographers coming into photography in the last half decade or so are led to believe that you must always use manual settings. The reality though couldn’t be further from the truth (just ask any professional photographer). Of course, there are times when manual is needed, but for any amateur photographer, these are a lot less than they think.
Using auto-ISO really is a time saving exercise, without detriment to your images, set it and forget it, and concentrate on what matters most… Your composition.
One Camera One Lens 
Hello Mark, Good writing, I also use auto iso on a regular basis, usually from 200-800 for standard lenses during the day, and 200-1600 for telephoto lenses during the day – sometimes even higher if I want to shoot birds in the forest with a 400mm, but rarely over 3200, because then the noise influences the details too much for my taste – that is with tele I mean. With standard and wide angle lenses you can indeed go further with ISO.
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It’s such a great setting that some refuse to use!
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