How I Learned to Stop Worrying and Love Auto ISO

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ISO is one of the three critical elements of exposure, and yet among the people I have talked to it seems to cause the most confusion. Aperture can be physically represented by simply making a circle with your fingers to represent the size of the opening in your camera lens, and shutter speed can be mimicked by closing your eyes, opening them briefly, and then shutting them. Neither one is a perfect comparison but it helps get the point across, especially to those who are new to photography.

ISO, in my experience, is a bit trickier to explain, and yet it can make or break a picture, even if you have the other two elements set just right. Or…it could make or break a picture in days gone by.

We have reached somewhat of a unique time in the history of photography in that ISO is, to some degree, no longer relevant in the same way that aperture and shutter speed still are. While I certainly would not let my camera choose the aperture and shutter speed for most of my shots, I have all but abandoned my misgivings about Auto ISO, and now almost always let the camera choose for me. As a photographer it has not been an easy leap for me to make, but it has been incredibly liberating, and I think it could be for you too.

A tack-sharp picture shot at ISO 4000 with minimal digital noise.

A tack-sharp picture I shot at ISO 4000 with minimal digital noise.

My first real digital camera, not counting a few point-and-shoot models I had in the early part of the previous decade, was a Nikon D200. It was a beast of a camera, with some features that outclassed even most modern models, like a maximum shutter speed of 1/8000 second and a weather-sealed body. One thing it did not do so well was high ISO values, specifically anything past 400. I could shoot at 800 in a pinch, but going all the way up to 1600 resulted in pictures that were a muddy mess and 3200, its maximum possible value, was an unmitigated disaster. This trained me to use the following thought process in virtually all shooting situations:

  • Shoot in Aperture Priority (I set the aperture and let my camera set the shutter speed)
  • Set the ISO to 100, 200, or 400 depending on the lighting
  • Select an aperture that would give me the depth of field or overall image sharpness I wanted
  • Hope the shutter speed wasn’t too slow so I didn’t get a blurry picture
  • If the shutter speed was too slow, raise the ISO to no more than 800
  • If the shutter speed was still too slow, compromise my artistic vision by opening up the aperture
auto-iso-sunset

Even my old D200 could produce some fine images, though things quickly went south above ISO 400.

It was a process that worked somewhat successfully, but often resulted in images that were compromised in one way or another. When I finally upgraded to a much newer camera, a Nikon D7100, I still had the same mindset when it came to setting the ISO. I wanted to do it myself, lest my camera make some kind of silly decision on its own, that resulted in a picture with way too much noise for my taste. For a while I used the same thought process as shooting with my D200, even though the D7100 had vastly superior high ISO capabilities (which have since been surpassed by nearly every modern camera on the market today including its own successor, the D7200).

At first I used the old rule that had been burned in my mind regarding anything higher than ISO 400, which was to avoid it at all costs. Despite the evidence right in front of my eyes I was still used to the old way of doing things, and mentally set my maximum threshold at ISO 800, which I told myself, could only be exceeded in the most dire of circumstances. It took me far too long to discard this line of thinking, and I’m hoping you won’t have to make the same mistakes I did to get there.

Shot on my D200 at ISO 400.

Shot on my D200 at ISO 400.

A Brief History Lesson

The term ISO is somewhat of a holdover from the days of analogue film, when you would go to a camera store and buy an entire roll of film with an ASA value of 100, 200, or 400. ASA 200 was twice as sensitive to light as 100, 400 was twice as sensitive as 200 (which made it four times as sensitive as 100), and so on. Once the film was loaded in your camera you could not simply change your mind and use a different value; you had to shoot the entire roll before changing to another ASA for different lighting conditions.

ASA 100 film was great for outdoor situations or other scenarios where there was a lot of light, just like shooting at ISO 100 on a digital camera. ASA 400 was better for indoor situations when you needed film that was more sensitive to light, if there was simply not much to work with. If you looked hard enough you could get film that went up to ASA 800 or 1000, but anything beyond that was about as common as a polycephalous bos taurus (two-headed cow).

I took this photo of a champion marksman on my old D200 at ISO 400. If you look super close at the trees you will see some noise in the image, but doing that kind of misses the point of the photo.

I took this photo of a champion marksman on my old D200 at ISO 400. If you look super close at the trees you will see some noise in the image, but doing that kind of misses the point of the photo.

Early digital cameras, not unlike my world-weary Nikon D200, did not offer much in the way of low-light shooting capabilities that their film-based counterparts didn’t already have. Even as recently as a decade ago if you wanted to shoot in a low-light situation you might as well just grab a roll of high-ASA film, since most digital cameras just weren’t very good at their (roughly) equivalent high ISO values. (ISO and ASA are not directly 1:1 equivalent, but the measurements can be treated as fairly similar for the purposes of comparison.)

However, all this started to change rapidly as digital sensor technology advanced over the years, and now we are at the point where virtually any consumer camera can shoot up to ISO 3200 or even 6400 (a value that was unheard of with analog film) without much of a penalty in terms of overall color and luminance noise. In fact, most digital cameras are so good they can set the ISO automatically (hence the term Auto ISO), essentially removing a critical element of the exposure equation altogether, and freeing you so you only have to think about aperture and shutter speed.

Why I Use Auto ISO

This line of thinking was what used to stop me dead in my tracks as a photographer. The whole reason I learned to shoot in Manual mode was so I could have more control over my photos! Why on earth would I want to give control back to my camera, as if it knows better than I do what settings I want? The answer, I discovered over several years of shooting, is not as black and white as I once thought.

In most situations, the primary element of exposure that concerns me is the aperture, since it dramatically affects things such as depth of field and image sharpness. Of course I also have to pay attention to the shutter speed, since I generally don’t want motion blur, which then leaves the question of ISO. After shooting with my D7100, and subsequently my full-frame D750, I have realized that in most cases, I’m happy to let my camera decide the ISO for me, because I simply don’t care about it anymore. This might sound a bit extreme, but I humbly submit that perhaps you shouldn’t either.

Shot at ISO 2000 on a three-year-old Canon SL1 (EOS 100D)

Shot at ISO 2000 on a three-year-old Canon SL1 (EOS 100D)

Some photographers are prone to pixel-peeping, and I must admit I am certainly one of them. Zooming in on a picture to 100% magnification, in order to take note of barely-visible imperfections is a great way to compare various aspects of cameras, lenses, and even similar photographs. Shooting at high ISO values will often reveal noisy blemishes that stick out like a sore thumb when viewed up close. However, what I have come to realize, even when shooting with my D7100 which is over three years old, is that I simply don’t need to view my photos at ultra-close range to enjoy them, and for the most part don’t care about the noise that shows up when I see those ISO values skyrocketing. If I have to choose between a blurry picture and a noisy picture, I’ll take the latter every time, and twice on Sunday.

How to Use Auto ISO

The exact mechanics of enabling Auto ISO vary from one camera to the next, but on most models from major manufacturers like Canon, Nikon, Sony, Fuji, Olympus and their peers, there is usually an option in one of the menus that allows you to do a few things:

  • Enable Auto ISO
  • Choose a maximum ISO value
  • Choose a minimum shutter speed

Once you learn to find your comfort zone with these settings, you might find yourself thinking less about ISO, and more about things like framing and composition. On my D7100 I’m comfortable shooting up to ISO 3200, so I set that as the maximum value. I have the minimum shutter speed set to 1/(2x lens focal length). This means if I’m using a 50mm lens and shooting in Aperture Priority, my camera will lower the shutter speed to no less than 1/100th in order to get a properly-exposed picture, and if that still doesn’t do the trick it will then automatically raise the ISO clear up to 3200.

Learning to relinquish this amount of control has been incredibly freeing, so much so that for a while it actually felt like I was cheating because I was not manually selecting the ISO for every single shot. On my D750 I use similar settings but set the maximum value at 6400.

As you play around with this on your gear you are going to have to find a solution that works for your individual needs and photographic taste. Some cameras only let you specify one single value for the minimum shutter speed (as opposed to calculating it based on the focal length of your lens) and your mileage for how effective this technique is may vary, but if you can learn to embrace Auto ISO and let your camera do some of this heavy lifting, you might find yourself getting a lot more keepers on your memory card.

For this impromptu Easter photo I set the aperture at f/3.3 and let my camera do the rest. It chose a shutter speed of 1/100 and then raised the ISO as high as it needed to (2800) in order to get a good exposure.

For this impromptu Easter photo I set the aperture at f/3.3 and let my camera do the rest. It chose a shutter speed of 1/100 and then raised the ISO as high as it needed to (2800) in order to get a good exposure.

I would be remiss if I did not mention some of the downsides of Auto ISO as well, as not all is bright and sunny, and warm and fuzzy on this side of the fence.

One of the most significant limitations of shooting at high ISO values is the lack of dynamic range – basically, how much data your image sensor is able to capture in a given picture. If you have a RAW file that was shot at ISO 5000, and you need to use Lightroom to recover detail from the shadows, or raise the exposure of the whole image, you will find you have much less room to work with than if you shot the photo at ISO 100.

Also, depending on your camera, you may also find cases of severe banding, or ugly horizontal lines, that show up when you try to recover shadow detail at high ISO values. Finally, all things being equal a picture shot at ISO 4000 will generally have less vibrant colors, and skin tones will seem a little more artificial and false, than a similar picture shot at ISO 400.

Selecting the ISO was the last thing on my mind; I used an aperture of f/4 and a minimum shutter speed of 1/100. My camera selected an ISO of 5000 and I could not be more pleased with the result. A year ago I would have never gone that high, and would have had a blurry photo instead.

Selecting the ISO was the last thing on my mind when I made this image. I used an aperture of f/4 and a minimum shutter speed of 1/100, my camera selected an ISO of 5000, and I could not be more pleased with the result. A year ago I would have never gone that high, and would have had a blurry photo instead.

Despite these limitations, shooting with Auto ISO has been a huge boon for me, and I think it could be for you too. If you have never tried Auto ISO, I recommend giving it a chance and see how you like the results. For me it was a little like enabling back-button focus, in that I was highly skeptical at first, but after a few weeks I was hooked and now I don’t think I could ever go back.

Do you use Auto ISO? Share your thoughts in the comments below, and I’d love to see some of your favorite high-ISO images as well. Cameras today really are incredible imaging machines, and it’s fun to see what they can do if we push them a little bit.

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Simon Ringsmuth is an educational technology specialist at Oklahoma State University and enjoys sharing his enthusiasm for photography on his website and podcast at Weekly Fifty. He and his brother host a monthly podcast called Camera Dads where they discuss photography and fatherhood, and Simon also posts regularly to Instagram where you can follow him at sringsmuth.

  • Glad to hear it, David! I was also surprised initially at how much freedom it gave me to just focus on shutter speed and aperture, and now I don’t think I could ever go back 🙂

  • zman2596

    I’ve been shooting about a year now and have a Canon SL1. Recently I started setting my ISO manually. I feel comfortable selecting my own ISO in ideal lighting conditions like outside, but after some recent inside/low-light scenarios, I wasn’t as impressed, especially with my daughter’s gymnastics and son’s basketball pictures. I was using aperature priority mode and raising ISO give me faster shutter. However, I think I did a bit unnecessarily and just complicated it more. I’m thinking of stepping back and using auto ISO again. Maybe I don’t need to minimize thinking and reduce pressure in those situations where I can.

  • Don DeFeo

    Simon, great article! I shoot a lot of corporate and event photography with majority indoor shots taken under really funky lighting situations in hotels and event centers. Mix of fluorescent, incandescent, spots, etc. Makes me nuts. Have found I have had to resort to FLASH with people shots to get better white balance/saturation of flesh tones and ambient light. Nikon 750 I did not find did the best with AUTO ISO and FLASH combo so I resorted to the old tried and true set ISO (400) and flash to get the best results. I DO like the idea of AUTO ISO and HAVE used it in other situations with super results (e.g., outdoor corporate golf tournament photos). Have not shot a lot of RAW at this point which would probably give me better white balance editing afterwards, but I am trying to hold my editing time down as most of these events want their shots pretty quickly for publications, etc. Am certainly open to any suggestions in this area! Always looking for the best suggestions for natural light and especially INDOOR photography where you CANNOT use flash (concerts, sports events, etc.).

  • Andy Carr

    Must admit I wasn’t sure how auto iso worked. Been using it all evening on my d610 and I have no doubt this is now my default setting

  • Shibu George

    I absolutely agree with your suggestion, there is no need to shy away from high ISO settings if you have to. This one shot at 10,000 ISO

  • abrianna

    Funny…I find myself using auto ISO quite a bit over the past few weeks for the reasons you mentioned.

  • Huseyin Faik

    Great article. Can really relate to this. Still shooting with a D7100 myself and after shooting a few kids parties which are invariably in poor light conditions discovered this method combined with an f2.8 lens and helped my results no end. Also felt like I was cheating at first but when you let go of that and just look at the results it’s a great technique which allows you to concentrate more on composition etc.

  • Hi Simon, I have a D7100 and the fact you can set the max ISO and also a baseline shutter speed meant I was thrilled at the prospect of the feature. In practice though, I found it was not quite how I imagined it would behave.

    I set the base shutter speed to 1/100 and the max ISO to 1600 (I saw in some many reviews the D7100 performed in the ‘excellent’ range up to this value). But I’d find the D7100 just did what it wanted… I remember looking at the EXIF of a few shots and it was something like 1/500th and ISO 800. I found myself wondering why it didn’t just use 1/100 and a lower ISO. The type of photography I do rarely ever needs a fast shutter speed, and if I do need that then I’m into shutter priority.

    Did you find the same? Do I need to revisit this and test it again?

  • While on my D7100 ISO1600 shots do still look great out of the camera, it’s when you
    start pushing the shadows and highlights in Lightroom that you really
    see the downsides of getting away from the camera’s base ISO as the
    noise shows up a lot sooner. That’s why I’m still very conservative of my ISO.

  • Irene McCullagh

    Try using manual settings with auto ISO. Then you can fully control the shutter speed and aperture yourself.

  • That’s awesome, Andy! I’m glad this is working out well for you.

  • Elaine, even if you don’t like it I appreciate that you are willing to give it a try. I find it useful, but I know it’s not for everyone 🙂

  • I agree with you on this, Jordan. I once took some portraits with my D7100 at ISO 800 that were severely backlit and found myself raising the shadows about two stops in post, which then resulted in some pretty severe banding and other nasty artifacts showing up. New cameras are much better at this though, and on my D750 I can push exposures several stops in post without any banding at all.

  • I must have been in aperture priority, as I am 90% of the time, but going into manual and having to control aperture and shutter speed kinda defeats the purpose of auto ISO, does it not? Aperture priority is effectively ‘auto shutter speed’ and shutter priority is like ‘auto aperture’.

  • Irene McCullagh

    I don’t know what purpose you consider defeated. Photography is all about light and in order to control light, you have three components : ISO, Shutter Speed and Aperture. If you are in aperture priority 90% of the time (as you state), that implies you are controlling ISO (because you have selected and set it) and you are controlling Aperture : you are selecting your f/stop. Thus the only component of the three which is in AUTO mode would be Shutter Speed – right? In other words, you are taking control of TWO out of THREE steps. In auto ISO mode, let the camera auto select your ISO while you – again – take control of the other TWO out of THREE steps, by setting the shutter speed and aperture.

  • pratyush

    Totally agree. Noisy photo is better than blurry one, any day of the week.

  • Tod Davis

    I think that it is a case of knowing your camera. when i first purchase a new camera i always experiment through the ISO range to see how far i can push it. With most (if not all) cameras you can set a limit on how high the auto ISO can go so just set it to what you are comfortable with.

  • Tugboat Jim

    My images have to look sharp and clean up to at least 40×60. Sorry, folks, I just don’t see that happening with images shot at very high ISOs. Your examples seem to be relatively limited in size. I shoot a Canon 7DMarkII and all Canon L glass. Most of my images are shot at high shutter speeds (1/1250 or faster). I have used AutoISO, but find it defeats what I need to achieve under my usual shooting conditions.

  • I understand what you’re saying, it’s just of little use to me the majority of the time, as most of the time shutter speed is of little consequence other than getting the correct exposure and avoiding unsharp images when handholding. Unless I’m on a tripod, in which case I’m in full manual with ISO fixed at 100.

    Auto ISO working the way I had anticipated excited me because it meant I potentially only had to look after ONE setting: aperture.

    I don’t see any benefit to working as you describe over using aperture priority and controlling the ISO manually? In fact, it requires more careful monitoring as if the camera is already at ISO100 and the image is going to be overexposed the camera has nowhere to go from there. If I’m in aperture priority and ISO100 the camera has an almost unlimited cap on the shutter speed (up to 1/8000) to obtain the correct exposure.

  • Irene McCullagh

    well, use it / don’t use it. It’s there and if you find it of no help to your specific type of photography, then ignore it. Other people find it very helpful. I use it virtually all the time. But… your mileage may differ and clearly does!

  • Thanks, it’s good to keep and mind and one that I hadn’t thought of.

  • Good article. I use auto-ISO a lot myself, much more so now that I also shoot film alongside digital. With film you are locked into a set ISO for 24 or 36 frames, using auto-ISO is one of digital photography’s great advantages and one to be embraced as a quality that can be extremely useful.

  • Right on, Pratyush 🙂

  • I also felt like I was cheating a little bit too, Huseyin! It’s tough to relinquish control of something like ISO to the camera, but once you do, it can really improve your photography as you found out 🙂

  • Irene McCullagh

    yes! that’s exactly the way I use it and I love the control / flexibility it allows

  • pratyush

    I love the idea. I’m going to start doing that. Thank u for suggesting.

  • Jack Mc

    The last time I tried Auto ISO it was overexposing on most of my shots, which now makes me realize that the metering mode setting is crucial for the camera to choose the ISO. Thanks for motivating me Simon!

  • You’re probably right about the metering, Jack. I don’t think auto-ISO by itself would cause your shots to be overexposed.

  • I remember being a little too conservative when estimating my upper ISO limit initially, and over time I started to get a lot more comfortable pushing my cameras a little more. I started to realize that I’d rather have noisy shots than blurry shots 🙂

  • Janet McPhail

    This was shot on my D810 at 6400 ISO. I took it using auto ISO and manually setting the shutter speed and aperture.

  • Craig Stephan

    I couldn’t agree more. I have been shooting Auto ISO since purchasing a D800 (virtually no digital noise at 6400). When hand holding the camera I set the MAX ISO to 6400 and shoot shutter priority unless I need to concentrate on depth of field. I general shoot at 1/125 sec. unless the subject is moving and then I shoot at 1/500 or higher. This gives me freedom to concentrate on composition and less on the technical details of the camera controls. When I shoot using a tripod I turn-off AUTO ISO, set ISO to 100 and use full manual settings to capture the image. I almost never miss a shot using these settings and have taught a number of other photographers the same technique.

  • barry schwartz

    Does your method of auto iso mean I would have to change the setting each time I change the lens (with a different focal length)? and how would I set it for a zoom lens?

  • On many Nikon cameras (which is what I shoot with) you can set the parameters of Auto ISO to vary depending on the lens you use. If I use my 50mm lens it uses a minimum shutter speed of 1/100 before raising the ISO. If I use my 85mm lens it automatically uses a minimum shutter speed of 1/170. I think you can do this on other cameras too, but I’m not sure.

  • Silvia

    I’m dumb but I’m pretty certain that you can’t use exposure compensation when using full manual mode, only in aperture priority or shutter priority.

  • Hi Silvia, exposure compensation is the missing piece of the puzzle.

    Not every camera allows for auto ISO, though these days it’s probably pretty rare. The original Canon 5D, for instance, did not offer Auto ISO. On the Canon 6D they finally offered the ability to shoot with auto ISO, but Canon dropped the ball when it came to auto ISO in manual mode. On the Canon 6D you can shoot with AUTO ISO in manual mode, but they did not offer the option to engage exposure compensation. Canon only offered EC when it automatic modes with Auto ISO.

    For cameras that offer auto ISO in manual mode, you set the aperture and shutter speed you want. If the light allows for the parameters you’ve set, the camera then chooses the ISO needed to make a properly exposed image. For cameras that allow you to tap into exposure compensation in this mode, you simply dial in the exposure compensation you want, essentially forcing the camera to choose a different ISO than it would have chosen.

    If I’m shooting a scene with lots of highlights that I know are going to fool the meter (snow for instance), I might bump my EC +1. Let’s say I set my SS to 500 and the aperture to 5.6. The camera wants to choose 400 ISO to make what it thinks is a proper exposure. I know by experience that one stop more light would be better. In this case forcing the camera to use 500/5.6 @ 800ISO by using EC would give me a better exposure than 500/5.6 @ 400ISO.

    I hope this helps!

  • Silvia

    Thanks for the explanation. I’ve been using auto ISO in manual mode for quite a while, but to my knowledge, neither of my two cameras allow for setting exposure compensation in manual mode. (Canon 60d, and Olympus em-10). I’ll look in their manuals just in case is there and I haven’t figured it out. Thanks again.

  • Niklas Isberg

    Great article and all the things you mentioned are very true. Although I must say that you can’t achieve certain things with auto ISO. Shooting a silhouette picture for example or taking photos at a studio. You can’t use off camera flash with auto ISO. These things are related to the style you shoot though. Im a strobist and like to keep the quality as sharp as possible. Whenever Im taking pictures of an event, I might use auto ISO. The thing with Olympus OMD E-M1 is that the digital noise is awful when shooting with something like 4000. It is usable but a lot of detail is missing. I used to shoot with Nikon D700 and one thing I miss is the great high ISO handling.

  • Catalin Danciu

    Hello! How about using AutoISO when shooting with flash on camera? Anyone can tell us how is working and some tricks?
    Thanks!

  • Vadim Sokol

    Haha! On Canon 5d MarkII AutoISO’s limit is 400!!!! WTF??? Is it some kind of jokes from Canon engineers?)))

  • Ultravixen

    Thanks a lot.

    I was using Auto ISO for a while, but my settings where too high, I decided to correct them using the ones you do (I have a D5100), and I do think that will help in the future indeed.

  • Tim Sugrue

    Does anyone else have issues with the camera chosing to go below minimum shutter speed regardless of what it’s set at? I shoot a Nikon d5300.

  • The camera lowers the shutter speed only as a last resort. If you’ve set the upper limit for Auto ISO to 3200, and minimum shutter to 1/200, then your camera will raise the ISO to 3200 in order to get a proper exposure without going below 1/200. However if it’s already at 3200 but still can’t get a good exposure it will start lowering the shutter speed as a result.

  • Tim Sugrue

    Thanks! I guess I’m just not comfortable with the camera making that determination for me and losing the shot. I appreciate the reply!

  • No problem Tim!

  • Crista SH

    Thanks for a great article. As a newbie and lover of Photography, I truly appreciate articles likes these that challenge traditional notions, encourage fun and learning new things. Ill give it a shot!

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