Is the D850 noticeably slower at AF than the D500?

[jhallettbc]

Now the prices of used DSLR are coming down I am considering buying a D850. I currently have a D500 and a D780. I have read that the AF focus on the D500 is faster. My question is the difference significant for someone who rarely takes BIF photos. My thinking is that if there is no big difference, then having a D850 would make sense--I would have both a FX and DX camera in one.
Another question is how does the AF compare on the D850 vs the D780 which has a new EXPEED 6 processor. Has anyone owned those cameras and seen a difference.

 

[Charles Loy]

I used the D850 a couple times for BIF, but went back to and staying with the D6 & D500 as the buffer is not deep enough and fills on the D850. It seems to focus skippy but the buffer is my concern. Never owned that D780, know nothing about it.

 

[NorthernFocus]

Not sure what you've been reading. I shot D500 and D850 side by side. The D850 is superior in every way including AF. Enough so that I sold the D500.

 

[John Navitsky]

i've not heard that the af on the d500 is faster, but it's possible it could be a smidge because of the faster fps, it'll have a bit more mirror down time during bursts. but in reality, i suspect you can't tell the difference

 

[John Navitsky]

Not sure what you've been reading. I shot D500 and D850 side by side. The D850 is superior in every way including AF. Enough so that I sold the D500.

there's no technical reason for af to be better on the d850 afaik?

 

[NorthernFocus]

there's no technical reason for af to be better on the d850 afaik?

Based on specs that's true. But based on specs the D500/850/D5 all have the same focus module so no reason the D5 should be any better either. They don't publish specs on what's under the hood. I've shot all three bodies. Side by side. AF isn't all about the focus module. Takes processing power to run the calculations. More processing power = faster calculations = faster AF. Price reflects the difference in what's inside. D850 cost 2x of D500 and D5 cost 2x of D850. You get what you pay for.

 

[MorganP]

The faster fps has nothing to do with the focusing. It is two different systems in the camera.
I have both cameras and the answer is no.

 

[NorthernFocus]

The faster fps has nothing to do with the focusing. It is two different systems in the camera.
I have both cameras and the answer is no.

As a matter of fact if anything the faster fps degrades AF. It's well documented(and I tested it myself) that blackout time of the D500 at 10 fps is about 60 percent. That's 60 percent of the time that the AF system is blind. Has to degrade performance.

 

[arbitrage]

I didn't find much in it but I preferred the D500 if I had to pick a winner for AF. Maybe it was the smoother shutter, maybe the extra 1FPS (not), or maybe it was the full coverage AF points but something just made me prefer it for fast action AF. Still, I really don't think there is much difference between them. I shot a lot of challenging BIF like swallows hunting bugs and got lots of keepers with both cameras.

 

[jhallettbc]

I appreciate all the feedback. I probably should sell both cameras to buy a D850. I don't understand why I have read here and elsewhere that people with both the 850 and 500 will still use the 500 for birds.

 

[brachypelma44]

I don't understand why I have read here and elsewhere that people with both the 850 and 500 will still use the 500 for birds.

A truly bottomless buffer and higher fps (without needing a big battery grip, either.)

However, if I'm unlikely to need those things, I really like the wider FOV of the D850 for acquiring and tracking subjects. It's a huge advantage.

 

[John Navitsky]

Based on specs that's true. But based on specs the D500/850/D5 all have the same focus module so no reason the D5 should be any better either.

While they share the focus module, the processor doing af in the d5 is faster.

AF isn't all about the focus module. Takes processing power to run the calculations. More processing power = faster calculations = faster AF.

Right, and the d500 and d850 BOTH are sporting an Expeed 5.

 

[John Navitsky]

The faster fps has nothing to do with the focusing.

My understanding is the faster fps gives the af sensor more "chances" to view the scene and make af adjustments. IE, 1 AF adjustment every 1/10s vs 1/7s vs 1/12s (d5).

 

[Ken Miracle]

At one point I had two D500's and a D850 ... if both using the same lens and both using the same CFexpress card and both with battery grip and EN-EL 18 battery then the D850 is only 1 FPS slower in frame rate. Focus speed not much difference. Buffer with high end CFexpress b cards not a problem and I have shot a lot of birds in flight with both. If I knew I was going to crop anyway I changed to DX mode in the D850. The fastest focusing camera I had was a D6. I have a Z9 on order and just got a Z6II as a low light back up. I sold the D500 and D6 and kept the most versatile of the 3 the D850 at least until the Z9 finally arrives.

 

[NorthernFocus]

My understanding is the faster fps gives the af sensor more "chances" to view the scene and make af adjustments. IE, 1 AF adjustment every 1/10s vs 1/7s vs 1/12s (d5).

What is the basis for that understanding? Did you read it somewhere? If so please share because hard/factual info on how the Nikon AF system works is scarce in my experience. What you say implies that the AF takes one sample/makes one correction for each shutter actuation. If that's true then what you say makes sense. However AF-C mode is "continuous" AF. Which implies that the AF works continuously at some sampling rate. In which case the longer the time between shutter actuations the more sampling it can do and the more accurate it should be. But that assumes all thing are equal(i.e. equivalent processing speed).

At any rate the question that @jhallettbc asked in the OP was " My question is the difference significant for someone who rarely takes BIF photos. My thinking is that if there is no big difference, then having a D850 would make sense...". The simple answer to that is that NO for practical purposes there is no BIG difference in AF speed of the two. Certainly not if you don't shoot BIF/fast action. Obviously based on the discussion/differences of opinion any difference in speed is arguable.

 

[Strodav]

I take both my D850 and D500 with me for wildlife / birding mainly with a Nikon 200-500mm f/5.6 and Nikon 600mm f/4G. When I can fill the frame, I use the D850, when I can't, I use the D500. I don't perceive much of a difference in AF speed and my keeper rate is about the same with both bodies. Besides the crop factor / mp, the biggest difference is 7fps vs 10fps. I'm not having any problems with buffer size when using 128GB Sony Tough CFExpress type B mem cards rated at 1480mb/s write speed.

 

[John Navitsky]

What is the basis for that understanding? Did you read it somewhere? If so please share because hard/factual info on how the Nikon AF system works is scarce in my experience.

I've read it a variety of times, but I think it's a theory more than something based on authoritative disclosure. As you point out, Nikon is not forthcoming about how the system works.

After mulling the issue, I think the theory makes sense.

What you say implies that the AF takes one sample/makes one correction for each shutter actuation. If that's true then what you say makes sense. However AF-C mode is "continuous" AF. Which implies that the AF works continuously at some sampling rate. In which case the longer the time between shutter actuations the more sampling it can do and the more accurate it should be. But that assumes all thing are equal(i.e. equivalent processing speed).

I didn't mean to suggest it takes "one" sample per actuation. I more mean that when the shutter is up (or in motion) there is *no opportunity* for new AF information to be gathered, so we know when the shutter is up the camera CANNOT be actively adjusting AF based on measured data (it may be making "blind" adjustments based on prediction, perhaps).

It's further complicated by the fact we don't know the details about the shutter movement -- how long it's in the up position, how long it's in the down position and how much it's moving.

As you said, we have very little concrete information and we're trying to figure out how the black box works.

At any rate the question that @jhallettbc asked in the OP was " My question is the difference significant for someone who rarely takes BIF photos. My thinking is that if there is no big difference, then having a D850 would make sense...". The simple answer to that is that NO for practical purposes there is no BIG difference in AF speed of the two. Certainly not if you don't shoot BIF/fast action. Obviously based on the discussion/differences of opinion any difference in speed is arguable.

Yes, I too believe there is no substantial difference between the D500 and D850 in terms of AF performance, which is why I said "theoretical" in my post.

 

[FB101]

I appreciate all the feedback. I probably should sell both cameras to buy a D850. I don't understand why I have read here and elsewhere that people with both the 850 and 500 will still use the 500 for birds.

Deeper buffer for one, better AF coverage and maybe a smidge better in AF acquisition with f:8 lenses (ie 500PF + 1.4x TC) but both suck compared to any recent mirrorless when it comes to f:8 AF.
The D500 also gets to 10fps without grip or special battery whereas the D850 is limited to 7fps without special equipment.

I just like the D850 better because it's both a D850 and 99% of a D500 in one body.

I do shoot the D850 with a grip and an EN-EL18 battery so the D850 gets 9FPS - but otherwise it's 7fps which can be a bigger gap vs the D500 10fps

 

[NorthernFocus]

I've read it a variety of times, but I think it's a theory more than something based on authoritative disclosure. As you point out, Nikon is not forthcoming about how the system works.

After mulling the issue, I think the theory makes sense.



I didn't mean to suggest it takes "one" sample per actuation. I more mean that when the shutter is up (or in motion) there is *no opportunity* for new AF information to be gathered, so we know when the shutter is up the camera CANNOT be actively adjusting AF based on measured data (it may be making "blind" adjustments based on prediction, perhaps).

It's further complicated by the fact we don't know the details about the shutter movement -- how long it's in the up position, how long it's in the down position and how much it's moving.

As you said, we have very little concrete information and we're trying to figure out how the black box works.



Yes, I too believe there is no substantial difference between the D500 and D850 in terms of AF performance, which is why I said "theoretical" in my post.

It has been documented with testing that blackout time is far worse on the D500. Over 60 percent vs less than 50 percent on D850. Never seen data on D5.

Just FYI since we seem to agree that none of this is meaningful to the OP.

 

[John Navitsky]

But based on specs the D500/850/D5 all have the same focus module so no reason the D5 should be any better either.

While they share the focus module, the processor doing af in the d5 is faster.

On this front, we should probably call-out that the D5 can drive the same mirror box faster than the d500 -- 12fps on the d5 vs the 10fps of the d500. Whether that is due to the faster processor, or having more power available via the bigger battery -- or a combination of the two, it's safe to say there's a lot of variables and we're not privy to what they are.

(My guess is it's due to the battery. It's interesting that you have different FPS on the d850 with and without the battery grip. I'm guessing the increased sensor size eats into the power budget.)

 

[NorthernFocus]

I appreciate all the feedback. I probably should sell both cameras to buy a D850. I don't understand why I have read here and elsewhere that people with both the 850 and 500 will still use the 500 for birds.

I think the perceived "reach" and unwilling/unable to shoot D850 in crop mode.

 

[John Navitsky]

I think the perceived "reach" and unwilling/unable to shoot D850 in crop mode.

And perhaps if they want the FPS without the bulk of the grip.

 

[NorthernFocus]

On this front, we should probably call-out that the D5 can drive the same mirror box faster than the d500 -- 12fps on the d5 vs the 10fps of the d500. Whether that is due to the faster processor, or having more power available via the bigger battery -- or a combination of the two, it's safe to say there's a lot of variables and we're not privy to what they are.

(My guess is it's due to the battery. It's interesting that you have different FPS on the d850 with and without the battery grip. I'm guessing the increased sensor size eats into the power budget.)

I agree battery power must be a factor in driving the mirror. D500 mirror is less than half the size/area and presumably half the mass. D850 speed is no doubt also limited by ability to read the high resolution sensor. Likely why Nikon pro bodies prior to Z9 have not been higher rez.

 

[JAS]

I think the perceived "reach" and unwilling/unable to shoot D850 in crop mode.

I find that shooting FX on the D850 allows me to frame the crop where I want it if I am not able to keep the subject properly framed in DX mode. But that is just me and my shaky hands.

 

[NorthernFocus]

I find that shooting FX on the D850 allows me to frame the crop where I want it if I am not able to keep the subject properly framed in DX mode. But that is just me and my shaky hands.

It's a tradeoff. Accept shallower buffer, less card space, and bloated files on computer for more working room in PP. We each have different needs. I find the 1.2x crop mode on D850 to be a nice balance.

Admittedly fps was never an issue for me because as I said above D500 was effectively 8fps(for me). And on serious shoots I use the grip and large battery.