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Author Topic: A7r3 vs D850 AF shootout  (Read 75907 times)

shadowblade

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A7r3 vs D850 AF shootout
« on: December 06, 2017, 02:26:58 AM »

Has anyone who currently has both bodies done an AF shootout between the two bodies yet? Perhaps also against the 1Dx2, A9 and D5?

They're almost indistinguishable performance-wise and interchangeable role-wise in almost every other respect - 42MP/10fps vs 45MP/9fps, similar DR, ISO 64 for the D850 vs better high-ISO for the A7r3, pixel-shift vs focus stacking.

For shooting things that don't move much, there's not much between them.

Yet almost every review has been about image quality rather than the one feature which could really set them apart from each other - AF acquisition and tracking on difficult subjects and their performance in the action camera role.
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BernardLanguillier

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Re: A7r3 vs D850 AF shootout
« Reply #1 on: December 06, 2017, 02:38:53 AM »

Dpreview just did, in short:
- D850 better at tracking
- a7rIII better at eye detection

Cheers,
Bernard

kers

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Re: A7r3 vs D850 AF shootout
« Reply #2 on: December 06, 2017, 03:30:34 AM »

... one feature which could really set them apart from each other ....

one has OVF + screen other has EVF+Screen
one is bigger - other is smaller
One uses lenses X other has lenses Y
One has focusshift other has pixelshift
etc etc
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shadowblade

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Re: A7r3 vs D850 AF shootout
« Reply #3 on: December 06, 2017, 03:53:03 AM »

one has OVF + screen other has EVF+Screen
one is bigger - other is smaller
One uses lenses X other has lenses Y
One has focusshift other has pixelshift
etc etc

And these have exactly what impact on performance - how well the camera can acquire and track a subject, and the technical quality of the resulting shot?

They're mostly aesthetic differences. Performance-wise, they're about as relevant as the fact that Nikon cameras save NEF files while Canon ones save CR2 files.
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shadowblade

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Re: A7r3 vs D850 AF shootout
« Reply #4 on: December 06, 2017, 04:01:00 AM »

Dpreview just did, in short:
- D850 better at tracking
- a7rIII better at eye detection

Cheers,
Bernard

Will be interesting to see if Nikon and Sony can improve on their weak areas with with firmware updates. The hardware to support it should be there in both cameras.

Also, what about tracking subjects with detectable eyes? (extending eye detection to animal eyes would be a huge deal for wildlife photography, and would be a welcome update to coincide with the launch of Sony's supertele primes next year)

Just as importantly, how do they do in comparison to the dedicated action cameras? If you track a cheetah running through long grass and pouncing on an impala with an A7r3 or D850, are you likely to get a long sequence of slightly-OOF shots, like you might with a D810 or 5D-whatever? Or is it still a credible effort (say, 1Dx or D4/D4s-level) - just not nearly as good as the latest-generation D5/A9/1Dx2?
« Last Edit: December 06, 2017, 04:25:46 AM by shadowblade »
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jeremyrh

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Re: A7r3 vs D850 AF shootout
« Reply #5 on: December 07, 2017, 01:20:22 PM »

On this subject do any action shooters have recommendations about which AF settings to use for different situations? I was at a dance workshop recently where the Nikon representative suggested not using tracking and use CAF with few points. Any comments?
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DP

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Re: A7r3 vs D850 AF shootout
« Reply #6 on: December 07, 2017, 06:06:00 PM »

Has anyone who currently has both bodies done an AF shootout between the two bodies yet? Perhaps also against the 1Dx2, A9 and D5?

blog.kasson.com = how happens that you don't know him = has D5, A7R3, D850 and many other bodies
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SrMi

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Re: A7r3 vs D850 AF shootout
« Reply #7 on: December 07, 2017, 10:50:53 PM »

On this subject do any action shooters have recommendations about which AF settings to use for different situations? I was at a dance workshop recently where the Nikon representative suggested not using tracking and use CAF with few points. Any comments?

CAF with one point (that I move around manually with the joystick) is often the best mode when photographing wildlife, or anything that moves around quite a bit. I only got D850 now, but that mode is what I used with D500, D5, D810 both for wildlife and landscape. Back button focus recommended as well. Do not prefer tracking on any of the cameras that I own.

You may want to read http://www.naturalart.ca/voice/blog.html for various wildlife Nikon specific settings. I guess the settings would translate well to a dance workshop or sport.
« Last Edit: December 08, 2017, 12:25:54 AM by SrMi »
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shadowblade

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Re: A7r3 vs D850 AF shootout
« Reply #8 on: December 07, 2017, 11:53:49 PM »

blog.kasson.com = how happens that you don't know him = has D5, A7R3, D850 and many other bodies

Don't think he's published an AF comparison yet. At least not one regarding moving subjects. There was an article a few weeks ago on the D850's AF precision when focusing on a still subject - no doubt the A7r3, which uses simultaneous PDAF and CDAF, will be more accurate than the PDAF-only D850 on a nonmoving subject, but that matters little if the subject's moving and the AF can't keep up as well.
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m.heijkoop

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Re: A7r3 vs D850 AF shootout
« Reply #9 on: February 17, 2018, 02:46:34 PM »

Battery life !!!
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hogloff

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Re: A7r3 vs D850 AF shootout
« Reply #10 on: February 17, 2018, 03:03:17 PM »

Don't think he's published an AF comparison yet. At least not one regarding moving subjects. There was an article a few weeks ago on the D850's AF precision when focusing on a still subject - no doubt the A7r3, which uses simultaneous PDAF and CDAF, will be more accurate than the PDAF-only D850 on a nonmoving subject, but that matters little if the subject's moving and the AF can't keep up as well.

Depends on the moving subject. Using eye AF the A73 tracks the subject extremely well once it has acquired the eye. Great for not only things like portraits where the model is moving, but also events like concerts where the subject moves around the stage.
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Jim Kasson

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Re: A7r3 vs D850 AF shootout
« Reply #11 on: February 17, 2018, 04:14:16 PM »

Don't think he's published an AF comparison yet. At least not one regarding moving subjects. There was an article a few weeks ago on the D850's AF precision when focusing on a still subject - no doubt the A7r3, which uses simultaneous PDAF and CDAF, will be more accurate than the PDAF-only D850 on a nonmoving subject, but that matters little if the subject's moving and the AF can't keep up as well.

I won't be publishing anything more than anecdotal remarks about moving subjects since I don't have a good quantitative protocol for that.

Here is a quick summary as to what I've found wrt comparing the accuracy of the two cameras with static subjects:

http://blog.kasson.com/a7riii/d850-and-a7riii-autofocus-accuracy-compared/

In general, I find that the big Nikkors focus faster than the Sony equivalents if there are any, and that in many cases, the Sony equivalents don't exist.

I also find the AF system in the D850 to  be not quite up to that in the D5, which is surprising given that Nikon says they are the same. I think that "the same" needs some explication.

Jim

kers

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Re: A7r3 vs D850 AF shootout
« Reply #12 on: February 17, 2018, 04:56:38 PM »


I also find the AF system in the D850 to  be not quite up to that in the D5, which is surprising given that Nikon says they are the same. I think that "the same" needs some explication.

Jim
Isn't it the difference between 20 and 46 MP?
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Jim Kasson

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Re: A7r3 vs D850 AF shootout
« Reply #13 on: February 17, 2018, 05:49:26 PM »

Isn't it the difference between 20 and 46 MP?

No, in at least one set of tests, the CoC spreads with the D5 are tighter, not considering the different pixel pitches.

Look at the second graph on this page:

http://blog.kasson.com/d850/nikon-d850-autofocus-accuracy-summary/

Anecdotally and subjectively, it seems to me that the D5 is faster with big fast lenses. I haven't made that comparison with the grip and D5 battery on the D850 though.

Jim

kers

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Re: A7r3 vs D850 AF shootout
« Reply #14 on: February 18, 2018, 06:42:52 AM »

...I haven't made that comparison with the grip and D5 battery on the D850 though.

Jim
OK
If the D850 can jump with the grip from 7 to 9fps i can imagine Af could be influenced too... would be an interesting comparison...
Did not think of that before...thanks... could be an other reason to use it.
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