Is This Exposure Mode Hindering Your Progression? The Limitations of Auto ISO for Wildlife Photography

As photographers, the choices we make in terms of our position relative to the light source, our perspective of the subject, and the moment we press the shutter, are some of the biggest factors that influence our images. Additionally, the ability to be exacting with how we render the exposure in our cameras is perhaps equally as important at times.

It’s true that we each have our own ways of doing things and there’s certainly more than one way to arrive at a proper exposure for a given situation. As such, I always try to approach my instruction with an open mind. It’s really easy to get caught up in the way that we’ve become accustomed to doing something, and convince ourselves that it’s the only way. With that in mind, I believe that I’m able to offer some valuable advice, having the unique perspective of seeing the images of many dozens of photographers – each of varying levels of experience, and differences of opinion – and how they’ve operated during my workshops over the span of the last ten years.

You might be perfectly happy with the way you’re currently operating in the field, and your resulting images, and that’s really what matters. However, if you feel that there may be room for improvement in your technique, or if you simply like my photographs and are curious to know more about my approach, you might find the following helpful.

After hundreds of hours instructing and examining the images of my workshop participants, certain patterns continue to emerge time and time again. There’s one recurring issue I notice continuously, to the point where I feel motivated to share this post, and that is the following…

Manual Mode with Auto ISO is the most misunderstood and inappropriately implemented exposure mode. Despite its merits in specific situations, its misuse creates confusion for many and often nullifies the major benefits of Manual Mode.

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How does Manual Mode with Auto ISO work?

Manual Mode with Auto ISO enables you to select and lock in both your shutter speed, and your aperture. As fast shutter speeds are often so critical in the world of wildlife photography, ensuring your camera won’t deviate from whatever speed you’ve deemed appropriate is of great benefit. It’s also beneficial for your aperture to remain locked in at your preferred setting – typically fairly wide open, as to let in lots of light, and better isolate your subject from its surroundings. As this mode allows you to decide upon the two creative aspects of the exposure triangle, it allows a great degree of control.

As the name implies, the third factor of exposure: ISO, is controlled automatically by your camera.

In order to avoid over or underexposure, your camera will select an ISO that neutralizes a given scene, creating a fairly “average” exposure. A dark forested scene will appear brighter than reality, and a bright snowy scene will be rendered darker.

An important detail that people don’t often acknowledge is, because your camera adjusts your exposure automatically by raising or lowering the ISO, if you change your aperture or shutter speed, this will not result in your exposure becoming brighter or darker. If you want to tailor the brightness of your image, you need to use “Exposure Compensation”. Just like in Aperture or Shutter Priority exposure modes, if you make a positive shift to your exposure compensation, the camera will make an adjustment to brighten the exposure. In the case of Manual Mode with Auto ISO, the camera achieves this by raising your ISO. Conversely, if you shift the exposure compensation to the negative side, the camera lowers the ISO to darken the exposure.

With most cameras, you’re able to set a parameter that disables your camera from surpassing whatever ISO setting you deem to be your upper limit. However, should your camera determine that the scene you’re photographing requires more light, but your camera has already hit that upper ISO limit, your camera will either simply underexpose the scene, or slow down your shutter speed until a proper exposure is achieved – this depends on the preferences you’ve set in the camera menu.

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Now that we know how it works, what are the benefits to using this mode?

This mode automatically accounts for changes in light, so in theory, you can point your camera at pretty much anything, and it will get you in the ballpark of a proper exposure. You set your desired shutter speed, your desired aperture, and the camera takes care of the exposure for a given scene by automatically selecting an appropriate ISO. This is of course very attractive to anyone who doesn’t want to miss out on fleeting opportunities, or those overwhelmed by the idea of controlling all three exposure variables.

This is a very legitimate and practical reason for having your camera in this mode. Let’s say you’re driving down a forest road and a rare animal suddenly pops up, in full manual mode, there’s a real chance of missing out on a once in a lifetime shot because you were trying to readjust your settings. This is an application where Manual Mode with Auto ISO makes perfect sense. You could preselect a fairly safe shutter speed of around 1/500th, and keep your aperture wide open at say f/5.6 to let in lots of light. If something should appear, your camera will immediately meter the scene for you and decide on an appropriate ISO, based off the available light, and the other two exposure settings you preselected.

The other situation where this mode is very effective is if your subject is moving in and out of variable lighting situations – let’s say a bear moving from deep shadows, into brighter areas in a forest clearing. The camera will identify the change in lighting and automatically adjust accordingly; likely faster than you ever could in full manual mode.


To summarize, the potential benefits of Manual Mode with Auto ISO are…

• Quickly generates a relatively accurate initial exposure
• Reacts to changing lighting conditions quicker than we can physically alter our settings

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So, why does this mode create problems for so many photographers?

Manual Mode with Auto ISO is a very useful tool that can improve your results greatly in certain situations, but issues arise from a lack of understanding of its functions, its limitations, and how to identify the appropriate times to use it.

As we now know, Auto ISO can account for your subject travelling through variable lighting. Its ability to alter your exposure during moments when we aren’t able to work quickly enough to do so ourselves is its main benefit. This sounds appealing, but we also need to consider the pitfalls of a mode that is continually adapting to perceived changes in the light, be that on your subject or its surroundings…

Inconsistent Exposures

I only infrequently encounter situations where the light on my subject is changing rapidly. So already, my need for Auto ISO is limited to very rare occasions. In fact, I generally try to avoid such situations whenever possible, as the uneven lighting tends to create undesirable effects in my images, regardless of whether or not they’re properly exposed.

Furthermore, what I do encounter during 100% of shoots are changing backgrounds, and variation in the size of my subject in the frame. Both of these variables can have a significant bearing over your exposure if shooting in Manual Mode with Auto ISO. These changes don’t have to be significant either; something as subtle as a duck swimming on the water towards you and turning more broadside, revealing a larger area of its darker plumage, is enough to change how the camera meters the scene. When framing up a scene at 600mm – a very narrow angle of view – a bird can make a subtle shift along a branch, and as you follow it through the viewfinder, suddenly the tone of the background can change dramatically. As your camera acknowledges these shifts, it will respond by changing the ISO, and thus the resulting exposure. Should these changes to your exposures be undesirable (as they often are) adjustments to your exposure compensation have to be made, which can be impossible at times given how quickly these changes in exposure can occur. This can be an irritating task that takes extra time to consider, and more often than not, photographers don’t even address it, leaving them with severely under or overexposed images – sometimes irreparably so.

In short, while touted as an amazingly practical mode for wildlife photographers, the way this mode adapts to perceived changes in light actually becomes your worst enemy in many of the most commonly encountered applications.

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Examples From the Field: Bald Eagles in Flight

Full Manual Mode

Manual Mode with Auto ISO – No Exposure Compensation

Each of these Bald Eagle images were taken within moments of one another in the same quality of low angle sunlight. In order to render a perfect exposure on the bird, no adjustments were necessary between frames when shooting in full Manual Mode, as the light on my subject did not change.

Had I been shooting in Manual Mode with Auto ISO, the pronounced differences in the bird’s surroundings would need to be accounted for by using exposure compensation, otherwise, the resulting changes to the ISO decided by the camera would’ve caused severely under and overexposed images, as seen above. This sequence played out in a matter of seconds; far too quickly for me to react with the necessary changes in exposure compensation.

By and large a huge hinderance in this sort of situation, the only conceivable benefit to Auto ISO here would’ve been if the eagle suddenly flew into the shade where the light was much darker, at which point the camera would automatically adjust the exposure. Though at that point, it begs the question, if you have a whole sequence of images in golden light, why concern yourself over getting something useable in marginal conditions? I’d personally much rather have a consistent sequence of exposures when it really counts.

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Considering all that, we have to ask ourselves this question…

Do we prefer the convenience of a mode that will quickly get us in the ballpark, as to avoid the initial investment of time to dial in our exposure fully manually?

OR

Should we spend the time to dial in our exposure, so that we aren’t consistently having to monitor any changes the camera is making, and counteracting those using Exposure Compensation?


To me, outside of very rare circumstances when you’ve had no time to assess your settings, and you’re just trying to grab a shot before a fleeting moment is gone, the answer is very simple: investing the time in the beginning to dial in your settings manually (a process that becomes increasingly expeditious with experience) is the option that will not only afford you more accurate and consistent exposures, but also frees you up to focus on composition and the behaviour of your subject, without being preoccupied with exposure compensation.

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Over and over, I hear the assertion from photographers who perhaps haven’t given full manual mode a fair shake, that it requires too much attention, such that it’s overwhelming and distracts from other aspects of photography. I would argue however, that in most situations, using Manual Mode with Auto ISO requires far more attention from the photographer. As we know, anytime your background changes, or your subject moves closer or farther from you, the requirement to constantly monitor your exposure compensation is onerous. Whereas in full Manual Mode, changes to your background and variation in the size of your subject in the frame DO NOT present issues. Your camera will not be influenced by these changes, because all of the exposure variables are locked in to your desired settings.

As opposed to the constant monitoring of exposure compensation in Auto ISO, in full manual mode, I’m very rarely altering my settings once I’ve initially dialed things in. I think many people would be surprised as to how low maintenance full manual mode really is!

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Examples From the Field: COMMON LOONS AND REFLECTIONS

Full Manual Mode

Take this situation for example:
1) A front-lit loon surrounded by bright golden reflections
2) A slightly side-lit loon surrounded by extremely dark reflections

Guess what I changed on my camera to render a proper exposure of the loon in these two very different scenes… absolutely nothing. This is because I was using full Manual Mode, and my settings were locked in to the proper exposure for the bird – bright enough to see detail in the darker plumage, but not so bright as to lose detail in the highlights. Because the bird’s surroundings were not influencing my camera’s exposure, nothing changed.

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Had I been using Manual Mode with Auto ISO, the camera would’ve registered that the bird’s surroundings became dramatically darker, and as a result, would’ve increase the ISO considerably to create a “proper” exposure. The result would’ve been an irreparably overexposed subject.

To avoid this, one would need to alter the exposure compensation considerably to override the camera’s decision to increase the ISO. Now imagine having to monitor this every time the reflections in the water changed, or when the bird moved closer or farther away, or when you wanted to change your composition to include more or less of the bird… now do all of that from a moving boat! Auto ISO in this situation is a total nightmare with absolutely zero benefits.

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Alternatively, you could use full Manual Mode, set your initial exposure once, and enjoy perfectly consistent exposures, regardless of your subject’s surroundings changing. Of course, as the sun rises higher in the sky and becomes stronger throughout the morning shoot, one will occasionally need to shave off a bit of light from their exposure. In this situation, every 15 minutes or so I might subtract 1/3rd of a stop of light using any one of my exposure variables. Infinitely more straightforward and less demanding than any automatic mode!

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Examples From the Field: SHort-eared Owl and Snow

Let’s have a look at this next example…

If we compare the flight shot and the properly exposed takeoff shot, with my full manual settings locked in, my exposure of course didn’t change, even though the owl’s surroundings varied from a dark midtone forested background, to nearly pure white snow.

Had I been using Manual Mode with Auto ISO, the camera would’ve responded to the bright surroundings, lowering the ISO considerably, resulting in a very underexposed image. Remember, if you’re surrendering control of your exposure to your camera, it will attempt to create an average exposure, rendering very bright scenes far darker than reality, and very dark scenes much brighter. As we know, one could of course shift their exposure compensation towards the positive side to counteract the change the camera decided upon, but again, in a situation with consistent light on the subject, there’s absolutely zero benefit to this mode.

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Examples From the Field: Black Bears and Changing Compositions

Zooming in from a looser composition to a frame-filling portrait had no effect on my exposure, because I locked in my settings in full manual mode. There was no need to set my camera to adjust anything for me, as the light was completely consistent.

In the tighter composition, the bear occupies a much larger portion of the frame. Had I used Manual Mode with Auto ISO, the camera would register the frame suddenly being filled with mostly dark tones. To neutralize the exposure, the camera would raise the ISO, resulting in an overexposed, midtone-heavy image. Not exactly accurate for a “black” bear.

This can of course be remedied by dialing down negative exposure compensation, but again, in a situation where Auto ISO offers zero benefit, this serves only as an unnecessary and annoying extra step.

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Examples From the Field: BUFFLEHEAD and handling contrast

It's true that today’s cameras are becoming increasingly forgiving when it comes to resolving exposure mistakes. By capturing a broader dynamic range, detail can be hiding in what once would’ve been an area clipped beyond repair. The advances in noise reduction software are revolutionizing post processing as well, by masking the undesirable effects of shadow recovery.

Having said that, there are still subjects, such as this Bufflehead drake, that are so high contrast, that a very precise exposure is necessary to render high quality results. Too dark and you’ll render more noise, less colour, and generally have less data to work with. Too bright and you’ll blow out the brightest areas. In order to be exacting with your exposure for such a situation, it’s very important to first find the right balance, then keep your exposure consistent. Considering this, it would be unwise to allow your camera any control over your ISO (or any exposure variable, for that matter). The slightest change in the pose of your subject, your composition, or the tones of the reflections will alter your exposure, invariably spoiling some of your shots. Compare that with the results of using full manual settings for this shoot: a batch of about 500 perfectly exposed images, all with different poses, sizes of bird in the frame, tone of background. To get to this point, I decided upon an appropriate shutter speed and an aperture (just as is required in Manual Mode with Auto ISO), and I set my ISO as to strike that balance of an ideal exposure, confirming with my Histogram that I’m not losing any detail, and off I went. Nothing more is required, other than the very occasional adjustment to my ISO as the sun’s strength diminishes throughout the shoot.

One could argue: “What happens if the sun goes behind a cloud and the light on your subject changes?”. While it’s true that Manual Mode with Auto ISO would adjust for this change in the light automatically, realistically I’m probably just going to stop shooting and wait for the sun to return, as the situation now lacks the critical ingredient of the right light. To me, so much of the success of this shot is dictated by the low angle sunlight showing off the bird’s iridescence. Additionally, even if I chose to continue shooting, it’s probably still easier to manually bump the ISO to account for the change in light, as opposed to relying on Auto ISO yet still having the demand of constantly monitoring your exposure compensation throughout the shoot.

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A Common Reasoning for Using Manual Mode with Auto ISO

“If I’m photographing a subject, and suddenly something else pops up behind me in different light,
I need my camera to adjust so I can get the shot!”

On paper, this sounds totally logical, and speaking purely from a getting to a reasonable exposure as quickly as possible standpoint, it’s a fair approach. But 95% of the time, I find this argument to be a moot point for me personally, based on the way that I photograph. If I’m concentrating on a subject, and I’ve spent the time to carefully choose my position based on light angle, potential foreground and background distractions, and inclusion of additional compositional elements, etc, if something else happens to randomly pop up nearby, aside from concerns regarding a difference in exposure, when considering all those aforementioned factors, what are the chances that I’ll just so happen to be in an optimal position to photograph it? In my experience, very, very low.

I think this notion of always needing the camera to quickly adapt implies more of a shooting from the hip experience, where one is walking around say a wildlife preserve, photographing whatever happens to pop up indiscriminately. There’s nothing wrong with this, and if that’s the case, I suspect an automatic mode like this would indeed give you the more consistent results that you’re after. With that said, if you’re someone motivated to improve your nature photography, approaching it in this sort of impromptu way brings about a whole other conversation that goes far beyond being scrupulous about exposure. To me, successful wildlife photography isn’t about taking photos of everything you happen to see, in hopes that something turns out; it’s about discovering opportunities that have the right ingredients, and focusing in on the specific needs of those situations. In short, I think to become a better photographer in this way, one has to understand that the majority of situations will not yield good images, and you have to be comfortable missing the odd shot here and there in the pursuit of the truly great ones.

I think realizing this was a crucial step in my progression; one that really changed the way I approach nature photography.

The less time I spent trying to force the issue, expecting to find some magic setting on my camera that would take a perfect image at the drop of a hat, no matter the conditions, the more time I spent learning to understand what made a particular opportunity great, and most importantly, understanding light. There’s almost a sense of relief when you start to accept that there are certain times when you can just admire your subject, and stop stressing about getting an image. It may seem counterintuitive, but learning to shoot less is one of the most important steps.

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I hope these insights have been helpful, and taken in the context of wanting to share what I’ve experienced as an instructor, and during my own personal photography pursuits. Differences in opinion as to approach and style from one photographer to the next, are of course inevitable, but for anyone hoping to increase their knowledge and skill surrounding the subtleties of nature photography, hopefully you can draw from this while forming your own conclusions of what works best for you. It’s all about gathering more tools for your tool box, and knowing when to take each one out.

Thanks for your interest!