(news & commentary)
Updated (new information on cause) — Nikon today issued a statement about the so-called flare issue of the D750. This problem shows itself as a dark bar across the top of an image where backlight is present, though it apparently is very angle dependent.
The interesting thing to me about Nikon’s statement is that all variations of it across the subsidiaries use some variation of the wording "we are already working on measures to address this issue,” which seems to indicate that Nikon is acknowledging that there is an issue.
The flare problem was not part of my original review of the D750 simply because I can’t produce it on my camera. Nor on another sample I borrowed. As with the D600 and D800 issues, I don’t generally write about problems until they can be verified in some way. Nikon’s statement seems to be a verification that there’s a problem.
The best account of the problem I’ve seen to date was posted by my friend Dave Etchells over at Imaging-Resource. Beyond knowing Dave to be a thorough and careful tester, I’ve learned to trust his conclusions about various things over the years. His article should be read by any D750 owner.
Note that you can’t see the problem through the viewfinder. The problem is internal reflections in the mirror box and the mirror itself blocks the light causing the problem prior to shooting. When the mirror lifts, the reflection can be triggered under some specific situations. It appears that the height at which the AF module is mounted—specifically the condenser lenses over the AF sensors—is the problem. On some cameras the condenser is up high enough into the mirror box that it generates the problematic flare, while on others it is recessed more and does not. One friend tells me that he has two samples that appear to have different condenser lenses from different sources; that could explain why some cameras exhibit the problem easily, while others don’t. The only way you’d see the problem in real time is via Live View, which is probably why it was first reported by videographers and documented in videos, not by still shooters.
The variation in AF sensor mounting height is one of those many manufacturing tolerance issues. You’re trying to align many different parts in DSLRs to get sensor/viewfinder/focus aligned, and even a very small location variation in one is trickles into all the others. In this case, the middle lens condenser appears to be getting mounted a bit high in some cameras, and is the source of the problem. In other words, it’s a hardware problem that requires camera modification of some sort. I’m not sure if you can actually just re-align everything that’s involved in a simple repair. So many parts all interact, it seems like it would be a fairly large teardown to adjust.
Why did this show up on the D750? Probably because of the attempts to slim down the body. I noticed as I was working on my review that the lenses over the AF sensors were relatively shallow in placement compared to some other Nikon cameras I own. That said, I couldn’t find that this was an issue on my own D750 or another I borrowed.
I’ll go on record as stating that this is again something that should have been caught by QA during initial production. Internal flare has been an issue since the beginning of DSLRs, as the filter glass over the sensor itself is more reflective than film is, and thus more light is bouncing around in the mirror box. QA should have internal flare testing as one of their checks during development, and they should have another test to insure that production bodies match what they found during development. A good QA department would note anything that changed that might impact internal flare, and perform tests to see if it did.
Okay, so let’s be fair. This problem is not going to affect most shooters. It’s only going to impact those shooting into light sources, and then only at some very specific, narrow angles. Moreover, it seems clear the problem isn’t in every D750 body. In other words, you could take thousands of shots and never see the issue, or you just may have a camera that will never show the issue. On the other hand, if you’ve got a contre-jour photographic style you may see the problem crop up often on a problematic body. Which is why the wedding photographers were the first to complain, as many do use contre-jour techniques.
So it’s not necessarily a big problem. Many, perhaps even most shooters will never see it.
What’s disturbing is that Nikon has made a strong push towards FX, and in doing so seems to now have a QA-related problem on virtually every camera (the Df being the exception so far). It’s great that Nikon seems more on top of the D750 problem than they did with the D600 and D800 ones, but nevertheless, brand reliability is a bit at risk here.
It’s tough to get everything right when launching new, complex products. I know, as I’ve been in that position before myself. It’s really the response you make to your mistakes that is more important. There are two responses we want to see from Nikon:
- Acknowledge quickly and fix.
- Put things in place so mistakes aren’t repeated.
With Nikon’s statement today, it seems that they’ve completed the first half of #1. We need to see them get to the second half of that quickly, too. But as I noted above, too many serious issues seem to be getting past QA on these high-end FX bodies, so I think we also need to see Nikon put more emphasis on #2, as well.
I’ve updated my review to put a pointer to both this article and Dave’s. My rating (Highly Recommended) remains unchanged at the moment, though I will continue to monitor this situation as it further develops.