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Gear Talk => Reviews => Topic started by: snappy604 on January 30, 2018, 07:06:38 PM

Title: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: snappy604 on January 30, 2018, 07:06:38 PM
I'll just leave this here...

https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii
Title: Re: 5d mkIV vs Sony AR7III vs Nikon D850
Post by: Talys on January 30, 2018, 07:35:14 PM
Thanks for the link :)

What is it with DPR and their obsession with AF tracking?  They also didn't mention that Dan & Sally stated that the live view autofocusing on the Nikon is unusable as a daily driver and in continuous mode is "worthless" and if you use live view shooting at all, the Nikon is terrible at that.

Also, at 6:46 check the pictures side by side.  The Nikon looked like poo to me.  The colors just looked flat.

The TLDR, they love the Sony & Nikon for different reasons (size vs does everything well), though they didn't say anything negative about the Canon except that the write time to SD was annoyingly slow in comparison.  And she likes Sony color science because she likes her skintones to push green (huh?).

Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: snappy604 on January 30, 2018, 11:00:30 PM
yeah didn't think it was the strongest comparison or very even. But what I did find interesting is in the end seemed to indicate they're all comparable and unless you need some of the minor differences each brings as an advantage, it's not necessarily worth jumping ecosystems.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: Talys on January 30, 2018, 11:51:08 PM
yeah didn't think it was the strongest comparison or very even. But what I did find interesting is in the end seemed to indicate they're all comparable and unless you need some of the minor differences each brings as an advantage, it's not necessarily worth jumping ecosystems.

Yeah.  Also, it's important to not just hear what you want to hear, when watching these videos.  Like, they gush all over the Sony, she does mention that there's hardly anything in the 200mm+ FL, but that since she just mainly does weddings, all she really needs is 24-200mm. 

A lot of it came down to preference, too. 
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: martti on February 05, 2018, 09:27:36 AM
Now you have this beautiful new Sony and you drop it.
It won't blink or go "beep".
The plan B? take it to repair, sure but I had to send my Sony to repair to Sweden (I live in France).
In the US of course the situation is different, so I hear. Sony is making an effort to bring the pro services to the level of pro demands. Is it there alreasy? Lens Rentals' Cicala thinks not.


An average customer cannot tell if there is latitude this or that much or some noise in the shadows.
But he can tell the difference of having a picture and not having one.


Canon's market share tells another story than the pixelpeeping tests do.
Pictures get sold.
If and only if you got them.




Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: bholliman on February 08, 2018, 06:56:25 AM
I'll just leave this here...
https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii

Of course, the D850 and A7R3 have the advantage of being released 1-1.5 years after the 5DIV, but since release dates never line up.  The 5DIV stands put pretty well against its newer competitors.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: 3kramd5 on February 08, 2018, 09:14:37 AM
I'll just leave this here...
https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii

Of course, the D850 and A7R3 have the advantage of being released 1-1.5 years after the 5DIV, but since release dates never line up.  The 5DIV stands put pretty well against its newer competitors.

The takeaway, as I see it, is that they all hold up. They are all three excellent all around cameras, and choosing one over another must involve weighing factors other than their photographic performance.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: jayphotoworks on February 09, 2018, 10:28:42 AM
I'll just leave this here...
https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii

Of course, the D850 and A7R3 have the advantage of being released 1-1.5 years after the 5DIV, but since release dates never line up.  The 5DIV stands put pretty well against its newer competitors.

The takeaway, as I see it, is that they all hold up. They are all three excellent all around cameras, and choosing one over another must involve weighing factors other than their photographic performance.

They are similar if you are comparing photography requirements. If you are comparing video requirements, the Sony would definitely be a better choice than the Nikon or Canon. Nikon would be a 2nd choice and Canon a 3rd choice although Nikon's video feature-set is is much closer to the Sony than Canon though.

The one redeeming feature with Canon bodies for video is DPAF. It is very very good, but not good enough to live with the other limitations or compromises of actually acquiring the video content itself.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: 3kramd5 on February 09, 2018, 11:00:33 AM
I'll just leave this here...
https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii

Of course, the D850 and A7R3 have the advantage of being released 1-1.5 years after the 5DIV, but since release dates never line up.  The 5DIV stands put pretty well against its newer competitors.

The takeaway, as I see it, is that they all hold up. They are all three excellent all around cameras, and choosing one over another must involve weighing factors other than their photographic performance.

They are similar if you are comparing photography requirements. If you are comparing video requirements, the Sony would definitely be a better choice than the Nikon or Canon. Nikon would be a 2nd choice and Canon a 3rd choice although Nikon's video feature-set is is much closer to the Sony than Canon though.

The one redeeming feature with Canon bodies for video is DPAF. It is very very good, but not good enough to live with the other limitations or compromises of actually acquiring the video content itself.

On datasheets I have to agree with that, but I am not a video guy so I can’t relate to real world differences.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: jayphotoworks on February 09, 2018, 12:50:50 PM
I'll just leave this here...
https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii

Of course, the D850 and A7R3 have the advantage of being released 1-1.5 years after the 5DIV, but since release dates never line up.  The 5DIV stands put pretty well against its newer competitors.

The takeaway, as I see it, is that they all hold up. They are all three excellent all around cameras, and choosing one over another must involve weighing factors other than their photographic performance.

They are similar if you are comparing photography requirements. If you are comparing video requirements, the Sony would definitely be a better choice than the Nikon or Canon. Nikon would be a 2nd choice and Canon a 3rd choice although Nikon's video feature-set is is much closer to the Sony than Canon though.

The one redeeming feature with Canon bodies for video is DPAF. It is very very good, but not good enough to live with the other limitations or compromises of actually acquiring the video content itself.

On datasheets I have to agree with that, but I am not a video guy so I can’t relate to real world differences.

The video features I use all the time on the A7R3 (I upgraded from the R2):

a) Focus Peaking/Zebra
b) HLG/SLOG w/ Built-In Gamma Assist
c) 5 Axis IBIS for all lenses
d) 4K (FF or S35) and 1080 @ 120
e) 2 Channel XLR Adapter XLR-K2M via Hot-Shoe (Audio straight into camera w/o 3.5 cables, etc.)
f) Dual video record on 2 cards simultaneously even @ 4K
g) Tilting screen LCD
h) An actual EVF
i) 2 hours of battery life in video recording mode w/ new battery FZ series

The firmware allows a lot of customization specific for hybrid shooters like myself. The camera allows different setups between stills and video mode. The custom buttons, etc. can all be set for one way for video mode and differently for stills mode. I have a custom recalled P mode, af-c+high speed burst set to the center button regardless of the mode I'm shooting in for stills, but in video mode, this doesn't apply, so I set it to a ff/s35 toggle instead. These ergonomic improvements are really appreciated by shooters like myself.




Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: Talys on February 09, 2018, 02:04:50 PM
As someone who is not a video guy, what I have never been able to wrap myself around is:

1. Why someone who is a professional/semi-professional/aspiring enthusiast video person wouldn't want a device ergonomically designed principally for video.  I mean, there's a reason that no pro camcorder (the ones used by video  crews) remotely resembles a photography device, and it isn't about money.

2. Why there is such a desire to combine photography and videography devices into a single package.

I mean, you don't see anyone wanting to take a pro video rig, and say, gee, it could take much better photographs... right?

I understand the desire to take home videos and videos for youtube or whatever (and not have to buy another device), but why would anyone care about 4k or codecs and such?  It seems like an inordinate amount of data for an audience that largely won't care.

Another way to put it I suppose: you see people who are the best in the world at taking photographs using the same or similar gear as people who make a hobby of it. But you see people who make major productions of video using wildly different gear and postproduction software as those who don't.


Now, I totallly get that someone who is a hobbyist doesn't want to spend $50,000 to get out the gate, or $2,000 to buy an empty bag to carry their gear.  But still, would it not make a whole lot of sense for there to be video-centric gear made for that niche, than to try to shoehorn them into still photography gear, and ESPECIALLY, DSLR gear, which was never, ever intended to be a primary video platform.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: BillB on February 09, 2018, 03:06:34 PM
I'll just leave this here...
https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii

Of course, the D850 and A7R3 have the advantage of being released 1-1.5 years after the 5DIV, but since release dates never line up.  The 5DIV stands put pretty well against its newer competitors.

The takeaway, as I see it, is that they all hold up. They are all three excellent all around cameras, and choosing one over another must involve weighing factors other than their photographic performance.

They are similar if you are comparing photography requirements. If you are comparing video requirements, the Sony would definitely be a better choice than the Nikon or Canon. Nikon would be a 2nd choice and Canon a 3rd choice although Nikon's video feature-set is is much closer to the Sony than Canon though.

The one redeeming feature with Canon bodies for video is DPAF. It is very very good, but not good enough to live with the other limitations or compromises of actually acquiring the video content itself.

On datasheets I have to agree with that, but I am not a video guy so I can’t relate to real world differences.

The video features I use all the time on the A7R3 (I upgraded from the R2):

a) Focus Peaking/Zebra
b) HLG/SLOG w/ Built-In Gamma Assist
c) 5 Axis IBIS for all lenses
d) 4K (FF or S35) and 1080 @ 120
e) 2 Channel XLR Adapter XLR-K2M via Hot-Shoe (Audio straight into camera w/o 3.5 cables, etc.)
f) Dual video record on 2 cards simultaneously even @ 4K
g) Tilting screen LCD
h) An actual EVF
i) 2 hours of battery life in video recording mode w/ new battery FZ series

The firmware allows a lot of customization specific for hybrid shooters like myself. The camera allows different setups between stills and video mode. The custom buttons, etc. can all be set for one way for video mode and differently for stills mode. I have a custom recalled P mode, af-c+high speed burst set to the center button regardless of the mode I'm shooting in for stills, but in video mode, this doesn't apply, so I set it to a ff/s35 toggle instead. These ergonomic improvements are really appreciated by shooters like myself.

It seems to me that anyone making purchase decisions about these cameras is likely to be vested in one (or more) of the camera systems.  These cameras as not likely to be anyone's first buy.  Also, anyone considering buying one of these cameras should be in a position to decide how important various features are to them, like video, which is more important to some people than others.   Realistically, for most people, the important question is what more the new model offers beyond the same maker's previous model.  What more do you get from a 5DIV than you get from a 5DIII, etc.? From my own experience, I found a lot of difference between a 5DIV and a 5DII, and I don't really care that much about how the 5DIV compares to various Nikon or Sony cameras.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: jayphotoworks on February 09, 2018, 09:22:59 PM
1. Why someone who is a professional/semi-professional/aspiring enthusiast video person wouldn't want a device ergonomically designed principally for video.  I mean, there's a reason that no pro camcorder (the ones used by video  crews) remotely resembles a photography device, and it isn't about money.

It doesn't mean we don't already. We might have found a converged device fits a particular use case better than a cinema setup that needs the size and weight, post production, crew size and support equipment loadout. In addition, it can also complement said cinema camera as a B-cam. The fact it shoots 42MP stills is a bonus.

Quote
2. Why there is such a desire to combine photography and videography devices into a single package.

Canon's 5D2 started the initial push into a stills camera being able to also capture video. Later on, as mirrorless started to mature it was a perfect fit for this medium. If you think about this, every digital video camera is already a mirrorless camera.

Quote
I mean, you don't see anyone wanting to take a pro video rig, and say, gee, it could take much better photographs... right?

Well, RED tried this approach with their Scarlet platform. Never really took off.

Quote
I understand the desire to take home videos and videos for youtube or whatever (and not have to buy another device), but why would anyone care about 4k or codecs and such?  It seems like an inordinate amount of data for an audience that largely won't care.

Depends on the audience. It's more than just home videos for youtube. My Iphone X does 4K @ 60 and 1080 @ 240 complete with zoom lens and OIS. I don't need an A7RM3 for that.

Quote
Another way to put it I suppose: you see people who are the best in the world at taking photographs using the same or similar gear as people who make a hobby of it. But you see people who make major productions of video using wildly different gear and postproduction software as those who don't.

Some of the best people taking photographs in the world are shooting on Hasselblad or Phase One cameras in excess of $40-50k. I'm sure most of us are not shooting with those cameras as hobbyists.

Quote
Now, I totallly get that someone who is a hobbyist doesn't want to spend $50,000 to get out the gate, or $2,000 to buy an empty bag to carry their gear.  But still, would it not make a whole lot of sense for there to be video-centric gear made for that niche, than to try to shoehorn them into still photography gear, and ESPECIALLY, DSLR gear, which was never, ever intended to be a primary video platform.

That niche is already being filled. Those people are already buying cameras like the GH5, A7S2, A7RM3, etc.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: 3kramd5 on February 09, 2018, 11:08:41 PM
I'll just leave this here...
https://www.dpreview.com/videos/0018045426/full-frame-showdown-nikon-d850-vs-canon-5d-iv-vs-sony-a7r-iii

Of course, the D850 and A7R3 have the advantage of being released 1-1.5 years after the 5DIV, but since release dates never line up.  The 5DIV stands put pretty well against its newer competitors.

The takeaway, as I see it, is that they all hold up. They are all three excellent all around cameras, and choosing one over another must involve weighing factors other than their photographic performance.

They are similar if you are comparing photography requirements. If you are comparing video requirements, the Sony would definitely be a better choice than the Nikon or Canon. Nikon would be a 2nd choice and Canon a 3rd choice although Nikon's video feature-set is is much closer to the Sony than Canon though.

The one redeeming feature with Canon bodies for video is DPAF. It is very very good, but not good enough to live with the other limitations or compromises of actually acquiring the video content itself.

On datasheets I have to agree with that, but I am not a video guy so I can’t relate to real world differences.

The video features I use all the time on the A7R3 (I upgraded from the R2):

a) Focus Peaking/Zebra
b) HLG/SLOG w/ Built-In Gamma Assist
c) 5 Axis IBIS for all lenses
d) 4K (FF or S35) and 1080 @ 120
e) 2 Channel XLR Adapter XLR-K2M via Hot-Shoe (Audio straight into camera w/o 3.5 cables, etc.)
f) Dual video record on 2 cards simultaneously even @ 4K
g) Tilting screen LCD
h) An actual EVF
i) 2 hours of battery life in video recording mode w/ new battery FZ series

The firmware allows a lot of customization specific for hybrid shooters like myself. The camera allows different setups between stills and video mode. The custom buttons, etc. can all be set for one way for video mode and differently for stills mode. I have a custom recalled P mode, af-c+high speed burst set to the center button regardless of the mode I'm shooting in for stills, but in video mode, this doesn't apply, so I set it to a ff/s35 toggle instead. These ergonomic improvements are really appreciated by shooters like myself.

The customization is certainly noteworthy. I played with my buddy’s r3, and it was in a completely different class than my r2 was (not to mention the original A7R I owned for 30 seconds). If I weren’t satisfied by my 1Dx I’d consider getting one.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: Talys on February 10, 2018, 01:13:12 AM
@jayphotoworks -

I the interest of not having a humongously long post, I won't quote your replies.  Thanks for your perspective; I genuinely appreciate it.  :)

For sure, there are cameras (and lenses) that are out of reach in price for hobbyists, like hasselblads, or even 1D's.  But essentially, these cameras have the same form as a much less expensive camera - right hand on grip with shutter, left hand on lens with twist zoom and focus, viewfinder, screen, dial near the top with shooting modes, right finger dials, etc etc etc.  Whether it's an A7RIII or Hassleblad or Rebel, you hold and shoot them the same way.

GH5, A7S2, A7RM3, same thing.  These are shaped like digital cameras, held like digital cameras, and used like digital cameras. 

I think that it's worth nothing that most (maybe, all?) pro photographers who shoot photos on medium formats ALSO have full frames, and use their full frame gear for different types of still photography, because FF cameras are just a different tool (for example, long telephoto lenses would be impractically humongous for medium format).

Now look at a RED or Arri Alexa, and they look (and work) a lot more like professional camcorders from Canon or Panasonic (and some of these are in the same ballpark as flagship DSLRs).   And the baby versions of these (consumer camcorders) bear much more resemblence to them.

Instead of mechanical ring zoom, W/T controls, lots of buttons on the right, something to mount your mic on, external batteries, like V-mounts, which allow power to run through them, or to be swapped without interrupting recording, lens hoods the aspect ratio of the video... and so on and so forth.  They look nothing like GH5/A7S2, because the what you need out of them is just very different.

Yes, it is possible to record an episode of House on a 5DII or a Sundance movie on an A7RII that will impress -- but most filmmakers don't want to, because of various output factors, but also because it's just not ergonomically optimal, right?

So, why do so many people whose job is to make  professional videos or whose hobby is videography in the same way that my hobby is still photography not want to invest in a midrange camcorders? 

I get that you're saying that some of you (like yourself) do -- and have videography equipment too -- but that does not seem to be the average person who complains about Canon bodies not having 4k video, or the average person who buys a Sony A7R3.
Title: Re: 5d mkIV vs Sony AR7III vs Nikon D850
Post by: Aglet on February 10, 2018, 03:48:26 AM
...
Also, at 6:46 check the pictures side by side.  The Nikon looked like poo to me.  The colors just looked flat...

(http://www.canonrumors.com/forum/index.php?action=dlattach;topic=34377.0;attach=174679;image)

and my tastes are quite the opposite.
to me the Nikon looks more realistic, not overly saturated, no magenta skin tones like the Canon and a much more satisfying tonal contrast curve compared to the Canon and Sony.
Nikon, Sony, Canon way last IMO for OOC with whatever settings they used.
All tweakable so pointless.
But that seems to be the type of over-contrasty images typical Canon users fancy.
Title: Re: 5d mkIV vs Sony AR7III vs Nikon D850
Post by: Talys on February 10, 2018, 01:58:44 PM
and my tastes are quite the opposite.
to me the Nikon looks more realistic, not overly saturated, no magenta skin tones like the Canon and a much more satisfying tonal contrast curve compared to the Canon and Sony.
Nikon, Sony, Canon way last IMO for OOC with whatever settings they used.
All tweakable so pointless.
But that seems to be the type of over-contrasty images typical Canon users fancy.

Fair preference; the reviewer loved the Sony, because it pulled green on skintones, which is not what I like.  I am one of those that prefers a magenta pull on skintones.  It would have been better if they had the 3 cameras set up right beside each other and taken pictures at the same time, because it really doesn't look like the light is falling on her the same way in each (for example, the shadows causing raccoon eyes in the Sony is not because of the camera).

To me, the Nikon looks desaturated, and I would definitely increase the color saturation in post.  And yes, I'm oneof those that likes contrast, as long as it looks realistic.

However, the color science is more than that, and the main reason I went from Nikon to Canon was that the OOC colors on Canon were more pleasing to me.  In my opinion, it can be very hard to consistently do those corrections in post, because it isn't just white balance and tint; also, the less work you have to do in post the better, in my opinion.

Title: Re: 5d mkIV vs Sony AR7III vs Nikon D850
Post by: Aglet on April 21, 2018, 01:59:51 AM
and my tastes are quite the opposite.
to me the Nikon looks more realistic, not overly saturated, no magenta skin tones like the Canon and a much more satisfying tonal contrast curve compared to the Canon and Sony.
Nikon, Sony, Canon way last IMO for OOC with whatever settings they used.
All tweakable so pointless.
But that seems to be the type of over-contrasty images typical Canon users fancy.

Fair preference; the reviewer loved the Sony, because it pulled green on skintones, which is not what I like.  I am one of those that prefers a magenta pull on skintones.  It would have been better if they had the 3 cameras set up right beside each other and taken pictures at the same time, because it really doesn't look like the light is falling on her the same way in each (for example, the shadows causing raccoon eyes in the Sony is not because of the camera).

To me, the Nikon looks desaturated, and I would definitely increase the color saturation in post.  And yes, I'm oneof those that likes contrast, as long as it looks realistic.

However, the color science is more than that, and the main reason I went from Nikon to Canon was that the OOC colors on Canon were more pleasing to me.  In my opinion, it can be very hard to consistently do those corrections in post, because it isn't just white balance and tint; also, the less work you have to do in post the better, in my opinion.

i mostly agree.  Canon, in general, had overall pleasing colors and good white balance, especially once they went to the more advanced color-sensitive metering sensors.  Ligher skin tones were often rendered quite nicely.
But I'd caveat that with "good light."  under backlit conditions like the example, and some other situations, I prefer some other mfr's interpretation.
Also, having an exceptionally clean raw file, which was previously not Canon's strong point, allowed more correction in post, if desired.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: bhf3737 on April 21, 2018, 08:39:38 AM
The video features I use all the time on the A7R3 (I upgraded from the R2):

a) Focus Peaking/Zebra
b) HLG/SLOG w/ Built-In Gamma Assist
c) 5 Axis IBIS for all lenses
d) 4K (FF or S35) and 1080 @ 120
e) 2 Channel XLR Adapter XLR-K2M via Hot-Shoe (Audio straight into camera w/o 3.5 cables, etc.)
f) Dual video record on 2 cards simultaneously even @ 4K
g) Tilting screen LCD
h) An actual EVF
i) 2 hours of battery life in video recording mode w/ new battery FZ series
I appreciate the requirement for your video use-case posted here. Actually the features mentioned here as necessary for video are mostly cosmetics from a professional perspective. At the end of the day, what differentiates a video-oriented camera from a toy video camera is the codec itself and nothing else. What makes ARRI different from GH5 or A7RIII is the codec (and the technology around it to capture best quality motion picture). That is what you pay 30-40K for it. If you capture and save garbage at 400mbps 4:2:2 it is still garbage and does not magically turn to gold. Same argument for the audio, too.
I remember once in you own post you also mentioned that Sony's codec is much weaker for grading and that is true.
It is nice to have some toy video features in a still camera and shoot a few clips here and there for fun, but I do not expect to get production worthy quality from it. Many of those youtubers who cry for video features either don't know what the video and the real video making tools are or suffer from the Dunning–Kruger effect!! ::)
Let's be honest with the tools we have for the needs we have and enjoy using them.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: AlanF on April 21, 2018, 09:04:35 AM
Returned this morning from New Zealand. Our guide in one of the reserves had a D850 and a Nikkor 400mm/2.8. He had great difficulty focussing on small birds in darkish foliage close by whereas my wife with a 100-400mm II on a 5DSR at f/5.6 and I with a 400mm DO II on a 5DIV at f/4 had no difficulties. This is just a one-off report, but it goes to show that there is more to AF than nominal sensitivity in ev at the centre or the ability to track.
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: tron on April 21, 2018, 10:28:05 AM
Interesting! Just 20 days ago I encountered some cases where I could not focus at small birds with my 5DsR and 400 DOII. Also I has encountered a case 13 months ago with 5DsR and 500mm f/4. In the latter case the bird was in the shadows and I was shooting almost against the sun. But not in the first case. Annoyed this year I changed AF servo settings to balance shutter release with af and turned the af ring manually! In fact I used kind of focus stacking since being short sighted I could not be 100% sure about my manual focusing. True these were rare cases but still annoying. 
Title: Re: Canon 5d mkIV vs Sony A7R III vs Nikon D850
Post by: Talys on April 21, 2018, 12:57:17 PM
Returned this morning from New Zealand. Our guide in one of the reserves had a D850 and a Nikkor 400mm/2.8. He had great difficulty focussing on small birds in darkish foliage close by whereas my wife with a 100-400mm II on a 5DSR at f/5.6 and I with a 400mm DO II on a 5DIV at f/4 had no difficulties. This is just a one-off report, but it goes to show that there is more to AF than nominal sensitivity in ev at the centre or the ability to track.

Interesting insights.  Thanks sharing!