How much of a difference does AI-based subject detection make to your photography? The technology should increase our hit rate, but how much of a difference does it make?
Any reasonable quality camera designed for wildlife, sports, vehicles, and other genres where the subject moves will have AI-driven autofocus settings. That function recognizes the specific subjects and locks focus onto them. It should result in a higher hit rate than old continuous autofocus and tracking settings.
I’ve been putting my newest camera through its paces capturing one of the hardest of subjects to photograph successfully: birds. They move quickly, are often partially obscured, and come in many shapes and sizes. Historically, they posed significant issues for the photographer. Would the AI work in ways better than traditional autofocus and tracking? Or is there still a way to go?
There’s a mistake that many reviewers make when they get hold of a camera that is different from their own: they set it up in the same way as theirs. However, no two cameras behave exactly alike. That is especially true when comparing different brands; the settings that work with, say, a Sony won’t necessarily match those required for a Nikon. So, although I will be talking about the settings I used for my camera you might find things work differently for yours.
With all the following shots, I used Continuous Autofocus with the Bird Subject Detection activated. I changed the number of focus points depending on the subject and the bird's environment.
Contrary to what is often recommended, I usually shoot wildlife in aperture priority. I am a great believer in letting the camera do the heavy lifting. When shooting near water or in the margins of forests, the light varies considerably. Consequently, faffing around in manual mode means I might miss the shot. Furthermore, with my camera, in A mode, I can still set a minimum shutter speed, and I changed this according to the subject and its proximity. Plus, exposure compensation only requires a quick turn of the front dial. For large, slow birds that were not close, I would set it to a minimum of 1/800th second. For faster-moving, close subjects it might be 1/3000th. I had the ISO set to auto.
Two other technological changes have also occurred within the last three years. Firstly, the dynamic range of the sensor has improved enormously, so highlight and shadow details are far more easily recovered without image degradation. As a result, a far greater exposure margin of error is acceptable. Secondly, the enormous improvements in noise reduction in development software allow one to reduce exposure to capture highlight detail and then, using software, recover shadow details without significant degradation of image quality from noise. That is beneficial as it increases the shutter speed.
Shoot Number One: Gulls, Good Light, Mostly Clear Skies
Gulls are not the fastest of birds in flight. So, unsurprisingly, I got 100% in-focus shots. My only issue was the length of the lens I was using and the birds’ proximity of the birds. When they got close, they were often larger than the frame.
Gulls are a great subject for learning to photograph birds in flight, especially on a windy day when they often hover facing into the wind.
For these shots, all the focus points were selected. Once the camera locked focus onto the nearest bird, it stayed locked onto its eye even if other closer birds moved into the frame.
Shoot Number Two: Barn Owl in Low Light
We went out in my car to photograph a barn owl I had spotted the previous day on my dawn cycle ride; the barn owl is a crepuscular bird so you will see it hunting at dusk and dawn but won’t often see it out in broad daylight unless rain has prevented it from finding food. The owl made just one pass on this morning, which wasn’t very close. It’s a large, shy bird and its speed can vary as it hunts.
It was a dull morning, five minutes before sunrise. Despite the low light, the autofocus latched onto the bird and stayed there. Then the bird flew behind a dark bush, so the ISO shot up to maintain the shutter speed. Amazingly, the camera followed it despite being mostly obscured by twigs. Mine was the only camera that did this. Again, not a great photo, but it demonstrates the outstanding capabilities of the AI autofocus and how effective the 8.5 stops of image stabilization (IS) is.
It's worthy of note that many bird-in-flight photographers switch off image stabilization; I don’t. In auto IS, I find that so long as I have space in front of the bird when I am shooting, I get the images well framed when panning left and right, and still have the other axes stabilized. It takes a little practice, but I find it works better for me than no IS.
I saw the owl dive for prey, but sadly, it was entirely obscured behind foliage when it reached the ground. Then, a passing cyclist inadvertently chased the bird off.
Shoot Number Three: Small Birds Among the Twigs
Other tests I have tried with semi-obscured birds have worked equally as well. A large bush a short way from my house is home to a dozen or so house sparrows. They are constantly hopping between the twigs. If the camera could see the bird’s eye, it had no problems latching onto it. Even when they were turned away, the hit rate, although not as high, was pretty good and far better than traditional autofocus and tracking. I used a single focus point for the shots where the bird was buried deeply in the bush.
Once locked on, the camera stayed focused on the bird. For sparrows on the periphery of the bush, I chose a small group of focal points, which was easier to align with the birds, but the camera happily followed the subject after that.
Pro Capture mode allowed me to buffer the images with continuous autofocus before fully depressing the shutter button. The birds moved faster than my reaction time, but because the camera buffered the images, it didn’t miss the action. Occasionally, the bird would move faster than the autofocus could cope with at 400mm and above (800mm equivalent) at f/4.5 where the depth of field was razor-thin and the bird was heavily obscured. However, the biggest problem was my inability to move the camera fast enough to keep the speedy little blighters in the frame.
Now you see it, not you don't. The above comparison shows two consecutive images in continuous shooting mode shot at 1/1000th second and set to 50 raw frames a second. Even at those speeds, the sparrow was out of the frame too quickly. Higher burst speeds are possible, but without continuous autofocus, so a better option for me would have been to zoom out from the 400mm used.
Shoot Number 4: Aiming into Blinding Light
The following image was shot towards a scene that was too bright to look at with the naked eye. One of the big advantages of mirrorless cameras is that you can shoot towards the sun without frying your retina.
I also photographed these redshanks flying across brightly lit water, again, shooting into the sun.
In both cases, I had the camera set to a cross-target pattern of 39 points.
Shoot Number 6: Flocks of Birds Distant Birds
This first shot is a flock of lapwings. Initially, I had a small focus target group set to nine points in the middle of the frame and the camera selected a bird there. As the flock swung around to land on the bank, the selected bird stayed in focus despite other birds being close to it and partially crossing it.
I also shot a more distant group of pigeons. Again, the camera stayed on the selected bird.
Shoot Number 7: Fast Flying Duck
The ubiquitous mallard flies at over 50 MPH. Very generously, this one flew back and forth. So, although I wasn’t quick enough to spot it the first time until it was lost in the distant clutter of the marina the camera latched onto it. I spotted it returning from a fair distance and fired off around sixty frames as it approached. Again, I had a cross-target group of 39 points that stayed on the bird.
Mallard flying away, approximately 300 yards away
Of the dozens of frames, all bar two were in focus. This was a huge improvement over pre-AI autofocus and tracking.
Conclusion
A couple of years ago, a veteran friend of mine described my previous camera’s bird tracking as having military precision. Its replacement is even better. I am not saying it never misses a beat, continuously shooting that duck, it did lose focus for a couple of frames out of the sixty or so taken, and those fast-moving sparrows buried deep in the bush did flummox it on occasions. However, I defy any camera to achieve 100% success in every circumstance. Most of the time, it was spot on.
In the comments here at Fstoppers, some other camera brand owners mentioned they were disappointed with the performance of the camera’s subject-detection autofocus. I have tried them, and they were not as bad as the commenters were making out, but shooting alongside other photographers, my hit rate was better. Whether that is my skills or my camera's superior autofocus I don't know; I suspect it's the latter.
ISO250, 500mm, f/5.6, 1/1000
Using AI still depends on the photographer and their familiarity with the camera they are using. When I swapped cameras with others, I didn’t get anywhere near a high hit rate as I do with my own, nor did they with mine. So gear familiarity is still important, as is the speed at which a lens can focus.
Photographing birds and other moving subjects has come a long way since the advent of continuous autofocus, tracking, and, most recently, AI subject detection. I can conclude that a camera’s ability to identify a moving subject, focus on it, and maintain focus throughout a sequence is greatly enhanced by AI and that AI greatly improves what I can achieve. However, it still requires the photographer’s skills to find the right settings for the camera they are using and the knowledge to anticipate the subject's behavior.
In short, all cameras with AI-based tracking do a good job, but there are still some differences between brands. Therefore, if you want to take up photography and shoot moving subjects, then AI-assisted focusing is the way forward.
Equipment used in this article:
OM System OM-1
OM SYSTEM M. Zuiko 150-400mm f/4.5 TC 1.25 IS PRO Lens
OM SYSTEM M.Zuiko Digital ED 150-600mm f/5-6.3 IS Lens (on temporary loan)
