AF accuracy up close and open...D810, D850, Z6

I mostly shoot friends and family, sports, an occasional wedding or event. I switched from a D800 to D810 when a deal on a refirb D810 made the swap reasonable. I have been generally happy with the functionality of the two D810's I have now.

 

One of the surprise benefits of the D810 vs the D800 for me has been what seems to be more consistent and reliable AF. I also noted that the D810 seemed to require less AF fine tune. The AF improvement I experienced did not seem to get much internet discussion. I have been happy with the D810 AF performance shooting sports in fairly poor lighting.

 

Still, the D810 AF system is not perfect. If I am doing portraits up close and near open with Tele's, it seems that the best expression photo in a series often is just ever so slightly OOF. This seems to be a DSLR thing, and the 36MP D810 files are not forgiving of AF plane of focus when viewed at 100%

 

I am sure that a Nikon Z mirrorless will be in my bag someday, but I am also considering upgrading one body to a used D850. A Z system camera using sensor based focusing "should" be able to reduce the number of slightly OOF shots, but a D850 still has some advantages, especially continuous tracking AF from what I read.

 

I would be interested to hear from those that have used a D810, D850, and maybe a Z6. If the up close narrow DOF AF capability of the D850 is similar to a D810, I would be more inclined to get a Z6 over a D850, I think. I plan to keep one D810 in either case as a 2nd/backup camera.

One of the surprise benefits of the D810 vs the D800 for me has been what seems to be more consistent and reliable AF. I also noted that the D810 seemed to require less AF fine tune. The AF improvement I experienced did not seem to get much internet discussion.

 

This was reported by users on nikongear when the D810 became out, and as a result I upgraded my D800 quite soon. I don't recall the details but I had much less need of autofocus fine tune on the D810 than other cameras, and less variation from lens to lens. Furthermore and this is the most important factor, my D810 did not require distance-specific adjustments to the fine tune to achieve optimal results, whereas my D800 did not work correctly at different distances with many of my fast primes using a constant fine tune setting; my 105 DC required -20 at infinity and 0 at close-up distances on the D800, and on the D810 -12 was perfect across distances. I since switched to the D850 because I wanted to use the radio-controlled remote flash system and this was not supported by the D810, but otherwise I would probably have stayed with the D810. The D810 is noticeably quieter also, than the D850 or D800. This is one of the features that I miss about it. The D850 does have a better autofocus sensor, and dedicated AF processor which does help.

 

As for getting eyes in focus consistently, this is a matter of lens also, and not only the camera body. Lenses such as the 70-200/2.8 FL, 105/1.4 and 24-70/2.8E (though this lens isn't quite as sharp as the teles) are excellent autofocusers and some of the advantage of the newer lenses' improved autofocus are seen also when using older bodies. The newer D850 has 99 cross-type sensors instead of 15, and they are distributed around a larger part of the frame, so it's easier to take advantage of them when the eyes are not around the center of the frame. I have found excellent AF consistency with the new Multi-CAM 20k cameras and new telephoto lenses but some of the wider angles, especially, are less precise, but this is true of old and new cameras obviously. I don't have hard statistics but I think I got around 70% of shots wide open in focus with the D810, in daylight, using a telephoto lens such as the 70-200/2.8, but with the D850/D5 it is around 90-100% (also with 105/1.4 Multi-CAM 20k results are excellent). With wide angles the consistency is not quite as good, so in a dimly lit interior environment with a 35/1.4 I might only get 70% in focus with the D5, whereas with the D810 it might have been 30-40%. In bright daylight also the 35/1.4 gives high consistency of focus, but not quite as good as some of the teles such as the 105/1.4.

 

I think if you just got a D810 I would keep it for a while and if you need better AF you can probably get a D850 at reduced cost a bit later when it is not in the highest demand. Currently, it is still pretty expensive. I would keep in mind the contribution of lenses to the AF performance, as both camera and lens contribute to the outcome.

 

While mirrorless doesn't have fine tuning issues, the first generation full frame Nikon mirrorless do not feature some of the subject-identifying features that Sony have implemented, such as eye AF. If you're particularly concerned about getting the eye in focus, I would perhaps wait for the next generation bodies.

Edited November 26, 2018 by ilkka_nissila

I don't have hard statistics but I think I got around 70% of shots wide open in focus with the D810, in daylight, using a telephoto lens such as the 70-200/2.8, but with the D850/D5 it is around 90-100% .

 

 

Ilkka, thank you, that is the type of info I was looking for. I would have pegged my hit rate at maybe a little higher than 70% (wishful thinking?).

Ilkka, thank you, that is the type of info I was looking for. I would have pegged my hit rate at maybe a little higher than 70% (wishful thinking?).

 

It may well be that you get better than that. It depends on subject, lighting, skill, and how precisely you want it to be in focus before considering it is in focus. Also it likely depends on whether you use the linear points in outer areas of the frame, or the center 15 which are cross type.

Actually, whatever the percentages are, if there were a significantly better chance that the few best images from a series would be more likely be closer to perfect focus, an upgrade would be worth it for me.

 

Thinking back, I started with an FM, 50/1.4 & 105/2.5. Maybe I am more critical now, but I got a lot of good results with that manual focus rig and others since then, lol.

Edited November 26, 2018 by robert_bouknight|1

If one has been using the D800 and D810, I think the D850 is the logical next step. I don’t care for the extra pixels, but AF is significantly improved.

 

The Z6 is an interesting camera; I just got one myself and so far have been happy with it. However, unless you don’t mind using adapters at all, it is a bit of a pain to use it as part of a Nikon F system. And as much as I like XQD cards, I think it is risky to use a body with only one card slot as a primary body to photograph weddings professionally. For anything that you must deliver results, I would opt for dual cards. I think a Z6 or Z7 can be an excellent second camera to get into mirrorless, but it will be another 2, 3 years before Nikon Z to gradually emerges as a mature system.

Edited November 26, 2018 by ShunCheung

I'd claim an improvement with the D850 AF sensor as well - and I also saw better behaviour between the D810 and D800 (and yes, the shutter on the D850 is louder than the D810's, although that's not hugely surprising given the extra speed). I think I heard that Nikon allowed for some telecentricity changes as lenses focus, although it'd be nice if they let you plug in focus points at various focal lengths, distances, and positions across the frame - it shouldn't be rocket science.

 

One gotcha on the D850: historically I've mostly used 3D tracking mode for focus (since I can hold down AF-On and allow for the subject moving a bit, or focus and recompose). On the D850, 3D tracking seems to use the "helper" points a bit more than I'd like - and it will lock onto something near the selected AF point if it's closer. I've had this trying to shoot through branches, and if someone's leaning forward it'll tend to lock on an eyebrow rather than the eye. With hindsight, it's probably why my D500 attempts to photograph sea otters short-focussed on kelp. I'm still experimenting, but single-point AF seems better - I have Pv overridden to select single point AF (and turn AF on); you can select various AF modes in combination with "start focus" for programmable buttons, but not 3D tracking, so that stays on AF-On for me. I've yet to master the joystick, and don't really think it's gaining me much over the multi-controller. The area mode is actually vaguely useful at last, too.

 

I do expect better AF accuracy from the mirrorless cameras on a static subject (maybe less luck tracking a moving subject); I still wish Nikon would implement an option of a final contrast-detect step on the dSLRs. You can always use live view, if needed, although I'm not all that sold on getting live view to target what I want it to.

 

To my surprise, coming (indirectly) from a D800, I find the speed of the D850 (with grip) to be useful for wildlife. The grip does seem to help slightly with AF tracking, and (I think) reduces blackout time, unless I've just got confirmation bias. And the D850 can hit 9fps with metering in 14-bit raw with a decent buffer size. The Z 6 drops to the same speed when you're doing 14-bit (vs 12fps at 12-bit), the Z 7 drops to 8fps, neither of them adjust metering, and I'm a little hazy on how well the finder keeps up at full speed. They'll be a lot quieter than a D850 at full chat, though.

option of a final contrast-detect step on the dSLRs.

 

Well the problem is that most F mount autofocus lenses are really bad at CDAF, the precision of control and speed (of executing small changes) just doesn't seem to be there. The Nikon Z cameras do not use CDAF at all with adapted lenses.

option of a final contrast-detect step on the dSLRs.

 

Well the problem is that most F mount autofocus lenses are really bad at CDAF, the precision of control and speed (of executing small changes) just doesn't seem to be there. The Nikon Z cameras do not use CDAF at all with adapted lenses.

 

Oh, even in "low light mode"? I'd have expected them to have the option at least with AF-P lenses - I thought that was what AF-P was for.

 

Still, I'm only suggesting the option as equivalent to live view. What I'd like is to use the finder, lock on a fairly static subject (or get very close) with the PDAF system, then do a final tuning tweak at the supposed AF point using the sensor prior to an EFCS shot. For a moving subject or where I don't have the extra half second, it would do more harm than good - but sometimes I'm shooting people talking in a dark room at f/1.4, or sometimes buildings in the dark, and any improvement to the hit rate would be nice. It's on my magic list of things to ask Nikon (and the rest of you over the holiday season), anyway.

Maybe it is not the best option, but I tend to use continuous AF for the close & open aperture photos. Sure, I might could focus a static subject from a rigid position more accurately with single AF (or live view for that matter), but in the real world, both subject and photog move. For me, this is the real appeal of AF. For static situations, I could do manual focus just fine except for the almost useless screens in most AF SLR cameras. When using manual lenses on my Sony A7, I can focus very accurately though it takes a little time, but then movement upsets that accurate focus.

I am not sure if CDAF is available with AF-P lenses, but the interview I read included Nikon state that only PDAF is used with adapted lenses. I agree AF-P should be able to do CDAF properly, but then it may be they're such a small population of lenses (only one FX lens) that they might not have given it special consideration.

 

LVAF in Nikon DSLRs is quite prone to hunting and in my experience this is especially true if the camera is hand-held and/or subject is moving. It does work ok in a typical static subject and camera on tripod scenario.

 

Anyway, these limitations are not there with the Z lenses.

Thinking about Ilkka's comments on AF internals of Nikkor lenses, maybe "perfect" focus won't happen every time even given static subject distance & live view determination. I can understand how it would be difficult to design a lens AF mechanism that is both fast and capable of very high resolution of movement. Interesting that maybe the newer AF module gets AF closer. My 105/2DC and 180/2.8 lenses vote for a D850 over a Z. I am sure that there is a good bit of slop in the mechanisms of those lenses. Of course, the 105/1.4 would be a nice replacement for the old 105/2.

 

At least taking more images for more focused results is "free" with digital, but that best image with optimal focus still seems elusive.

Edited November 27, 2018 by robert_bouknight|1

Wait... 105 f/2 DC and 180mm f/2.8? As in screwdriver AF lenses? Which won't autofocus at all on the FTZ adaptor?

Nope, no screwdriver 'drive' in there!

 

Thanks to Shun for the pic below.

 

I was apparently incorrect regarding CDAF in F mount adapted lenses:

 

IR Interview: A deeper dive with the Nikon Z7 engineers

 

My wrong information came from the earlier version of the imaging resource interview, which they have now corrected. Both CDAF and PDAF are used with native and adapted lenses. However, user reports and reviews suggest that the native lenses have some advantages for focusing.

 

By the way: notice the relatively complex optical system in the EVF.

Screwdriver AF means yet another pretty strong motor inside the FTZ adapter to drive those old 80-200mm/f2.8 AF/AF-D, 300mm/f4 AF, etc. There were some 300mm/f2.8 screwdriver AF lenses too, but most people have moved onto AF-S.

Yes - if there were a screwdriver motor I'd kind of accept the size of the FTZ's lump. I'm just surprised it's that size solely for driving the aperture lever.

My wrong information came from the earlier version of the imaging resource interview, which they have now corrected. Both CDAF and PDAF are used with native and adapted lenses. However, user reports and reviews suggest that the native lenses have some advantages for focusing.

I am not sure you were actually wrong - CDAF and PDAF are definitely used but it could depend on the focusing mode (pinpoint mode is using CDAF) and the Nikon statement not necessarily means that they are used together in any of the focusing modes.

 

Kasson has some suspicions about that - but nothing conclusive: Z7 w/ 105/1.4 static focus errors in various AF modes

Edited November 29, 2018 by Dieter Schaefer

Yes - if there were a screwdriver motor I'd kind of accept the size of the FTZ's lump. I'm just surprised it's that size solely for driving the aperture lever.

Andrew, keep in mind that there is the tripod socket in the middle of that lump. There isn’t that much room for the aperture motor, which must be quite precise to change the little mechanical lever from f1.4 to 2, to 5.6, etc. It doesn’t go below f5.6 though.

 

An adapter with an AF motor will be very bulky. Someone will likely make one some day.

Andrew, keep in mind that there is the tripod socket in the middle of that lump. There isn’t that much room for the aperture motor, which must be quite precise to change the little mechanical lever from f1.4 to 2, to 5.6, etc. It doesn’t go below f5.6 though.

 

Surely it does for actual shooting, though - it must still be possible to select an f/11 aperture even if it's held at f/5.6 during composition, no?

 

And yes, although a bit of me thinks there's a tripod foot because the adaptor is so bulky, but the adaptor is bulky because there's a tripod foot, and there's a hole in my bucket.

Sorry, wrong comment on my part. During actual capture, the aperture control will stop down to whatever (small) aperture selected.