Nikon D850: the 2nd Sample is Off Also, both Skewed and Bad Flange Focal Distance
Related: digital sensor, flange focal distance, lens mount, Nikon, Nikon D850, Nikon DSLR, quality control
See my Nikon wish list.
Update 30 Oct: I’m puzzled. I set out to repeat the symmetry behaviors at a very far distance (a mile or so)—they don’t show up in the consistent blur-on-one-side fashion. However, I do see significant variation across the frame with 3 different lenses (Nikon 105/1.4E, Sigma 135/1.8A, Zeiss Milvus 135/2)—some of that could be field curvature or build tolerances in the lens. And yet the examples such as the Sigma 135/1.8A examples and the Nikon 105/1.4E test clearly show a problem.
Also, does testing at 100 or 200 or 400 or 1000 meters with an 85mm, 105mm, 135mm lens make that much of a difference versus infinity? Perhaps, since focusing mechanisms must rotate internally. But it was also 30°F colder in testing today, which means the lens mount, sensor and lens all contract slightly, which could also change behavior. Perhaps there is even slop in the lens mount itself—I always felt uneasy about the spring-type Nikon F lens mount; compare it to Fujifilm GFX or Hasselblad X or Canon EF and they seem much more solid, particularly those two medium format cameras.
Whatever the root cause(s), I am now thinking they are multivariate: camera sensor-to-mount parallelism, mount flexibility, focusing distance, temperature, etc. But why then did my trusty D810 seem so bulletproof in consistent behavior? 36 megapixels is only 1.11X different (linearly) from 45 megapixels—not significant.
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I’m growing irritated with the Nikon D850, that is, the 2nd sample I have been shooting. More on that below.
The first one had awful problems with sensor to lens mount alignment causing severe left/right skew as well as a flange focal distance error. Nikon PR says it “will take some time” for Japan to give a response. But it has been 15 days since I made the inquiry back on October 12 (25th as I write this).
It is unacceptable to hang any user out to dry like this, let alone a professional photographer. Or is Nikon trying to hide something? Surely a company proud of their product would want to be all over this, immediately. At this point, stonewalling is what I call it.
I have a phone, Nikon has a phone, what exactly is the problem?!
The 2nd Nikon D850
The 2nd sample does not behave well either. It has the same flange focal distance error as the first sample, and it too is skewed, though it is milder, making it harder to spot.
A 45-megapixel camera has to be held to extremely tight tolerances. A higher-res sensor cannot simply be shoehorned in without also tightening up build tolerances. From what I can tell from two bodies, builder tolerances for the D850 suck. The first body in particular shows a serious failure in quality control—it should never have made it into a box without being adjusted to eliminate the problem. That would cost money (to verify and if necessary, to fix). But like lenses it may be a case of shipping and letting the user figure it out and ask for service.
My evidence, and I suppose I should now go prove it with more lenses:
- The Nikon 105mm f/1.4E shows left/right skew.
- The Sigma 85mm f/1.4 DG HSM Art shows left/right skew.
- The Sigma 135mm f/1.4 DG HSM Art shows left/right skew in every aperture series and example I shot.
- A Zeiss Otus 85mm f/1.4 APO-Planar hand-tuned by a master technician and then MTF tested to be symmetric to within a 2% MTF difference corner-to-corner at f/1.4 shows left/right skew. If you ever get a lens that perfect, go buy lottery ticket ASAP.
Perhaps this is a “perfect lens storm”, and all of these lenses are “off” including the one proven to be as symmetric as the finest cine lens. And maybe I just won the goofy lens lottery.
When softness on one side of the frame is not fully overcome by f/5.6 (or f/2.8!), that’s a big problem. That’s what I’m seeing with the Sigma 135/1.8 and the Nikon 105/1.4E (well, the Nikon 105/1.4E “gets there” at f/5.6, but not f/4).
Both the first and second samples of the D850 have quality control issues with the sensor to lens mount distance (flange focal distance). Is this sloppy build or deliberate? I have it from an unimpeachable authority confirming this flange focal distance issue as I reported it, it being a distinct error versus my Nikon D810 and all its predecessors for years now. What the heck is going on?
What I want to know from Nikon
- Is the flange focal distance issue poor quality control, or is it a deliberate change?
- Can Nikon service adjust a D850 body for correct flange focal distance?
- Can Nikon service adjust the sensor to lens mount alignment to be to extremely tight tolerance?
The answers to these questions are extremely important for discerning professionals. Until I get answers, I’m feeling extremely reluctant to plunk down $3300 for a camera that can’t shoot straight. I need these answers and I expect so do other Nikon D850 buyers.
