In one very important respect, I feel sorry for Nikon.
Both D750 problems fall into those issues that you really struggle to deal with as a manufacturer. Yes, the defects are almost certainly there. But how many people will actually encounter them? In both cases for the D750, the answer is only a few.
The initial D750 problem had to do with the placement of the AF sensor module and its intrusion into the mirror box, coupled with the small shielding flap that flips when the mirror goes up. If you hit just the right scenario with direct light hitting the top of the AF sensor assembly at the right angle, it gets reflected up into the image area, adding to the flare there and revealing shading from the flap, which makes for an artificial cutoff of the flare and an obvious visual defect in the image.
My D750 couldn’t reproduce this problem with any amount of trying, but another I borrowed took only an hour for me to trigger ;~).
The latest problem is what Nikon calls “shutter shading,” and it seems to only occur at high speed sync with flash (Update: I’ve seen one complaint now about it occurring at 1/200 without Auto FP; but it seems clear to me that the problem is related to the synchronization of the shutter and flash fire point). At least those are the only cases I’ve seen so far (1/250 or faster shutter speed; the D750’s flash sync speed is 1/200). If that’s the case, and if you never move the D750 off the factory defaults, you simply will never see the issue. Even if you do set Custom Setting #E3 to one of the two Auto FP modes, you don’t always see the issue. I haven’t triggered it yet with my camera, though I haven’t quite done as much testing as I did with the original problem yet. The people I know that have triggered it were all using Auto FP.
So here’s Nikon’s dilemma: out of tens of thousands of users, maybe hundreds have encountered the issues. Probably less given how few examples you see posted. So do you repair all the cameras?
Morally, yes, you probably do. So I have empathy and sympathy for Nikon here. They’re trying to do the right thing, even though it’s disrupting a lot of folk who are suddenly feeling paranoid about their camera and rushing to send it back to Nikon. Indeed, as I was writing this, I received two emails that I would characterize as “paranoid response.”
So I feel sorry for Nikon. One is an esoteric assembly issue that was tough to catch. The other is probably an issue with a parts supplier not meeting specifications. Yet neither problem has had a lot of impact on D750 users.
Still, as much as I empathize with Nikon on the D750 problems, here’s what I think Nikon is still getting wrong: they’re not actually fully disclosing the problem. If I’m right that the current service advisory is for an issue with Auto FP sync—heck even if it was just flash sync in general—and disclosing that to the D750 owners would make those customers a lot less paranoid. In fact, it would almost certainly lower the strain on Nikon repair centers at the moment, as I can tell you that a lot of shooters would just avoid Auto FP for the time being while waiting for a more convenient time to send the camera in for repair.
This is why I’ve hammered Nikon so often on their communications. Those communications are more often than not opaque, veiled, incomplete, or un-informing. Such poor communications just ratchets up the response from the customer base in ways that harm Nikon more than help it, so I don’t understand why they just won’t address their communications problems and fix them.
I suspect that it’s partly fear of legal repercussions that is driving Nikon to say so little, so poorly.
Nikon, here’s the thing: most of your users are far less likely to sue you if you’d just be more open and upfront. You’ve made many of them so paranoid that their first impulse is to punish you. I’m pretty sure that’s not what you want to happen, but it is happening.
Give us the clear, complete, and useful information we need to make critical decisions about our tools of choice. I personally would never punish you for that, and I’m pretty sure virtually all of the Nikon user base would say the same thing.
The D750 is a perfect example of what I wrote in the previous paragraph. Nikon marketed the D750 to pros, and it was especially taken up by wedding photographers. Those folk are busy right now. Very busy. They don’t want to send their camera back to Nikon for repair until probably July or August if they can get away with it. But they don’t have the necessary information to know what is triggering the shutter shading issue, thus they have no idea if they could avoid it in their current use of the camera. One botched wedding shot is a huge liability to them, and they don’t know if it’s avoidable with their camera.
So, if shutter shading always happens no matter if flash in use or not, then so state that (e.g. “The shutter shading issue can happen at any time and is not predictable. For critical imaging work you need to send your camera in right away and we’ll fix it as quickly as possible.”). If it only happens with FP Auto, then state that (e.g. “The shutter shading issue is an intermittent one that only happens with FP Auto set in Custom Setting #E2. If you can avoid that setting, your camera should operate as expected and you can delay sending your camera in for repair. We advise you to send the camera in when you can be without it for a two to three week period.”). [For what it’s worth, I believe the current advisory is the second case, not the first case.]
That’s what we want to be fully on your side, Nikon. But thank you for making the right decision. I’m sorry that this happened to you.
[Article updated to indicate that it might not always be Auto FP flash.]