I have tested the accuracy of the Sony a7RII autofocus for static subjects; the results were impressive. I have used the camera for many actual photographic people shots. On the whole, the autofocus systems (I say systems, because there are a dizzying number of modes and sub-modes) have performed their task with remarkable flexibility and precision. The combination of phase detection (to get close) and contrast detection (to trim up any residual errors) is powerful in concept, and generally well-executed in practice. Of course, there are always things I’d like to see changed in today’s cameras and I’ll get to my suggestions for improvement in a future post.
Rather than post an endless and unenlightening procession of “look, it focused that perfectly” images, today I’m going to concentrate on what happens when you take the camera out of its comfort zone. There are those who will call me a Cassandra. While I understand that paying more attention to the negative aspects rather than the positive ones does not give a balanced view of the camera, today’s cameras all do so many things so well that a review that uniformly emphasized what’s good and what’s bad would be very long, much the same from camera to camera, and not provide much content that would help people get the most out of the camera in question in proportion to the length of the review.
If a camera does some thing just fine, the photographer doesn’t have to think about that thing at all. If a camera has deficiencies — and they all do — the photographer is benefited by knowing about them, so that she can avoid the situations which bring the deficiencies into play, or mitigate them with workarounds.
Last month, I took a few images of my oldest granddaughter swimming butterfly. I used the Nikon D810 and the Nikon 80-400mm f/4.5-5.6 ED VR AF-S Nikkor (the name doth flow trippingly off the tongue, does it not?), with the lens set to 400mm, and the aperture set wide open, which, at that focal length, is f/5.6. I set the drive to continuous low, and the autofocus mode to continuous.
Here’s what resulted:
Yesterday, with Sony a7RII and Sony 70-200mm f//4 OSS FE in hand, I asked me granddaughter to swim some ‘fly. I set the aperture to f/5.6 and the focal length to 200mm. I experimented with letting the camera find the subject, with flexible spot mode, with single shot, with continuous low and continuous high, with pretty much everything I could think of. I never got a good shot.
I think I know a few reasons why.
When a person swims butterfly coming towards you, there are moments when she is under the water, and moments when she is out of the water. this confuses continuous autofocus, which works by predicting the subject’s rate of closure with the camera. This is true for both the Nikon’s all-phase AF system and the Sony’s hybrid system. Once continuous AF is confused, it must focus very quickly once the swimmer comes out of the water.
The Nikon setup I used is faster than the Sony setup. I don’t know how much of that is the camera, and how much is the lens. I have no way of testing, but I do know that autofocus speed is highly dependent on the lens. The older Nikon 80-400 was snail-slow, and the Nikon 400/2.8 is shockingly fast, both used on a D3 or D4. The new Nikon 80-400 is a lot better than the old one, but by no means in the territory of the 400/2.8. Still, it was fast enough to get the job done, and the Sony 70-200/4 wasn’t.
Autofocus speed may relate to battery capacity as well. The motors in lenses could benefit from a lot of current for a short period of time to increase focusing speed, and that current may not be available from cameras with small batteries, like the a7RII. That relationship could be fixed with the addition of a supercapacitor, but I don’t think Sony would want to incur the cost, size, and weight penalty for what has got to be a corner case.
I did have some success with the a7RII by the pool. Breaststroke turned out not to be quite as challenging.
There is another difficulty connected with using the a7RII on this kind of subject. I never could use single shot mode to pick the right moment to make the exposure. I think that is because of the latency introduced by the electronic viewfinder system in the a7RII. It seems to be even worse when the camera is operated in continuous low mode. If I’m right about the source of the problem, and it is not a subtle problem, the only solution for mirrorless cameras in this situation would be a faster viewfinder refresh rate.
Jean Pierre says
This pushes the limit of mirrorless! Even a higher rate of EVF will not solve it.
I would take video for sports photography and take out single images. With a good video software you can download single images losless.
What did you use in A7R II “Display Quality” Setting? Not suggesting it makes this an OVF camera, but I had screen lockups and 1-2 second periods of “slideshow” mode when using my A7R II + LA-EA3 + 70-400 SSM2 with AF-C on an airshow. The culprit was “high” setting on Display Quality, turned it down to “standard” and things got much better. No more lockups and refresh/lag seemed better.
Sony Documention claims that Display Quality only affects battery consumption, but I’m gonna have to disagree with that, at least with LA-EA3 + 70-400.
Turns out that I was already using Standard, but thanks for the tip. BTW, what’s your recommendation for the way to set up AF for a subject like this? Which modes work well together?
Jean Pierre says
Fullframe mirrorless are not up to the mark. A6000 would give better AF-result! MFT would be the best.
And focus peaking….. no, chance with EVF delay!
For quick movement shot I would go with MFT!
FF mirrorless is for stil …. or use video-mode for quick movements.
For a swimmer I’d go AF-C with just Flex spot (sized S or M so what face gets covered easily) or Expand Flex spot and aim manually. Lock-On AF would propably get confused by the waves/splashes, it always seems to wanna “lock too big” so in the pool I’d expect to see big box that tries to cover both swimmer and her waves. I bit same with “wide”; I got a bit lazy in the airshow and tried “wide” focus area ==> AF-C was happily tracking “show smoke” from the planes. In the pool it would propably get confused by the waves/splashes as well.
I would also test shooting wide open, in AF-C the Aperture seems to stay stopped down after initial lock (instead of just stopping down for the exposure) and the tiny sensor-PDAF sensels really want all the light they can get, so I’d test that even in the expense of DoF. And actually wide open seems to maintain best screen refresh as light gets lower.
As for shutter mode, I’d propably go with single, even continuous slow seems to hamper timing with those tiny screen freezes and 2 fps is too slow to catch any sequences anyway.
Come to think of it, for the buttefly I’d propably just take my A6000, use settings above and burst 6 or 11 fps fps and pick the the keepers the ~15-20% accuracy would give me 🙂
Here’s an off-the-wall suggestion, why not take the photographer out of his comfort zone, rather than the camera? Try manual mode with focus peaking for shots where you have the ground/water in the frame. Have you thought about that? Big red haze over everything in focus and you shift it along with your target? It’s very, very reliable with just a couple minutes’ practice.
Madison Bond says
I owned a Sony A7Rii and found that AF on subjects moving toward the camera, particularly at higher focal lengths, failed often (my particular use case was dogs running on the beach). The same was true in dim light on static subjects…I often could not get it to achieve focus. I ended up selling it and going back to my Nikon d810. Too bad, because I otherwise loved the sensor, the EVF, the tilt screen. I haven’t seen that many reports about this particular weakness of the A7Rii, but it was my experience. With the new Sony A9, I will be interested to see if Sony has been able to improve AF performance and achieve parity with a DSLR.