Auto ISO: Yay or Nay?

By Cory Disbrow on July 30th, 2012   |    Posted in:  Photography 101   |    6 Comments

Happy Monday everyone! For today’s post, I’d like to talk a little bit about the Pros and Cons of a feature that has made its way into most cameras, and that is Auto ISO.

What is Auto ISO?

Auto ISO is a setting that you can use on most newer high end point and shoot, mirrorless, and DSLR cameras. Instead of the photographer setting the ISO at something like 100, 400, or in low light situations all the way up to 1600 or 6400, the camera will select it for you. If you are in Aperture Priority mode, the camera will select the ISO and the shutter speed while you select the F Stop. In Shutter Priority, you pick the shutter speed, camera picks aperture and ISO. In Manual Mode, you select both the aperture and shutter speed, and the camera will set what it finds to be an appropriate ISO.

Pros – When does it work?

Auto ISO can be REALLY helpful in certain situations. One of them is an environment where the light levels are changing a lot. A perfect example of this was the recent Hyperspace Hoopla show during Star Wars Weekends at Disney’s Hollywood Studios. The show is done on a large stage where the light changes every couple of seconds or every minute. For a show like that, you can set a shutter speed and aperture that you want, and the camera can pick an ISO for you. This is, of course, in Manual Mode. Doing so can result in shots like this:

Did I have to do some slight noise reduction on this image? Yes, but it was ok since it froze the motion and I actually came away from the show with a sharp shot of this moment.

Another place that Auto ISO works well is somewhere there is lots of motion on your behalf. Something like Kilimanjaro Safaris at Animal Kingdom. When you ride the Safari, you have to not only worry about trying to nail an exposure with a good shutter speed to freeze the subject, but you also have to deal with motion from the animals, a very bumpy ride, and changing light levels. So, again, you can go right into Manual Mode and select an aperture and shutter speed that will get you what you want, and then let the camera take care of the ISO. Then, when you transition from a bright scene on the savannah to a dimly lit spot like this one near the giraffes, you don’t have to worry about making camera adjustments, and you can just focus on hitting focus and getting the shot you want.

Cons – When will you dislike it?

While Auto ISO has its perks like described above, there are some times where you will find it silly. One of these is when you are doing a handheld shot in lower light where nothing is moving. Like a landscape during blue hour when you don’t have a tripod. You might only need a shutter speed of 1/25 of a second since you have IS on your lens. But, when in Auto ISO, the camera won’t understand that you have IS and then change the ISO to something higher to get you a faster shutter speed. That will result in the same exposure, but since you are at a higher ISO, you’ll introduce unnecessary noise into your image.

Another absolute bear of Auto ISO is something that can be prevented if you simply use your noggin, but is something that after a long day of shooting in a Disney park is something you might forget. When you shoot off the tripod, you need to turn it off! The other night, I noticed a beautiful blue hour sky at Hollywood Studios, and I sprinted (ok, walked casually) over to Echo Lake to capture it. I setup the 7D on the tripod, and went into all the work to go into LiveView to get a sharp focus, bracketed my shot, and used the 2 second timer to get the shot. After it was done, I looked at the LCD and was super pleased, and very excited to get home to edit the shot. Well, when I got home and ran the three shots in Photomatix, I saw a ridiculous amount of noise. I was completely flabbergasted as to why this was. I shot off the tripod, the exposures seemed relatively long, and they looked good on the back of the camera. Auto ISO struck. Oops. ISO 3200 for all three shots of the bracket off the tripod.

You might not be able to see what I see on my huge monitor with the full size image, but there is a lot of noise in the sky, and a whole ton of it on the boat here. It was a salvageable shot, sure, but it could have been infinitely better if I could have just remembered to turn off Auto ISO and shot at ISO 100.

Do you use Auto ISO?

Auto ISO has its highs and lows. It can be a very useful tool in certain situations if used correctly, but it can also be a huge Achilles Heel. Do you use Auto ISO? Let us know in the comments!

Thanks for reading, and have a great day!!


  1. tazlikesrobots   |   Jul 30, 2012

    I never used auto ISO, usually stick to 100 – 800 ISO, but that is the old film guy in me. May have to venture out on my next trip to WDW….

  2. Ryan Pastorino   |   Jul 30, 2012

    A trick I learned from Gregg Cooper is to use Auto ISO when shooting hand held brackets. It helps keep aperture and shutter speeds consistent throughout the bracket, especially in manual mode. This also helps keep the overexposed shot from getting too slow minimizing your chance of having that shot ruined by camera shake.

  3. Scott S. Baxter (Pixie Dust Pictures)   |   Jul 30, 2012

    Yes, I share the frustration with Auto ISO. It could be very useful for those of us who shoot for HDR at night. If there were a way to set it so that it kicked in only as needed to keep overexposures to the 30 second maximum (without having to go to Bulb), that would be very good indeed.

  4. Tom Bricker   |   Jul 30, 2012

    Unless I’m shooting on a tripod, I’m almost ALWAYS using Auto ISO.

  5. Mearn   |   Jul 30, 2012

    I find Auto ISO useful in a few situations, usually on rides or during shows when I know there’s no chance of getting away with 100 or even 800 but I don’t want to make the noise any worse than I have to. I’d get more use out of it if my body allowed me to adjust the exposure bias in Manual mode when using Auto ISO. I may need to look into my cameras options for metering more, but if I’m on a dark ride and shooting in shutter or aperture priority, I’m probably going to have the exposure bias down by about a stop. If I’m in manual mode, the camera is going to push the ISO up until it gets to “optimal”, which often means an overexposed and unnecessarily grainy image.

  6. Alan Rappa   |   Jul 30, 2012

    I’m hit or miss on the AUTO ISO. When I’m being lazy (which is more often than not) I have AUTO ISO on, but the camera’s brain isn’t quite wired like mine is.

    Often times I find auto ISO trading off my shutter speed instead of bumping up the ISO. While that probably a smarter choice, it makes it difficult sometimes to hand hold a shot on a crop sensor. Makes me wonder if the algorithm is geared more towards full frame sensors.

    I also find myself forgetting to take the camera out of AUTO ISO and therefore DESTROYING some night shots when I’m not paying attention.

    On the other hand when shooting in the parks during the day, AUTO ISO can be a life saver – especially when walking in and out of shops/attractions and back into the bright Florida sun.



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