Hi,

In another thread I had noted one issue I'd had with the D4 was that when the rear button (AF-ON) was used to focus instead of the shutter button it would only fire in "release priority" mode and not "focus priority" mode.

Even if a1 and a2 are set to "focus priority", when focusing with the AF-ON button the camera will fire the shutter when there are no objects in focus.

When focusing with the shutter button by using a half press, focus priority works just fine, so it seems the camera is capable of this.

Anyway I wrote Nikon about this and their response was:

"Thank you for contacting Nikon USA customer support. The behavior that you describe it the correct performance for the D 4 the camera is designed to function that way."

I thought surely someone had just made a mistake, so I submitted the question again, very clearly outlining the issue. Today's response was:

"Yes that is correct, focus priority is not available when custom menu item a4 is set to AF-ON"

So what I was sure was a firmware bug is, in fact, a feature.

There is nothing I could find in the manual to indicate this. As well, typically when something isn't an option it is greyed out on the camera menus - so I'd expect that if a4 was set to "AF-ON" then 'focus priority" should be greyed out in menus a1 and a2.

Anyway, I can work around it, but this whole thing struck me as a little odd.

Every Nikon camera, before the D4, D800 and D800E perform as you say, not as Nikon responded. The D4 and D800/E seem to have changed this. If you assign the AF to the AF button only, it seems Focus Priority is overidden. This is a bug, not an intended operation IMHO. Customer support will always give you that kind of response. i bet if you talked to a technical person that understands the camera, they would say, you you are right, that's different then intended.

On the D1 list I follow, some would disagree that it is a bug. They have always contended that when the AF Button is not being pressed, then the photographer is essentially in manual focus mode and the camera should fire when you press the shutter button. They also state that not allowing the camera to fire when the button is not being pressed is the bug. I can see that point of view and maybe Nikon's engineers decided that that group was correct.

Now talk to me about actively using the AF-Button while using focus priority mode. I'd think it should confirm focus prior to firing but Nikon stating that the setting and the AF-Button having nothing to do with each other could also be intended. I agree it would have been better if the setting couldn't be selected after having set to AF-Button only.

Anyway, that's why you need to learn how to use a new camera when you get it. Every camera tends to act differently for better or worse.

I guess I can see that side of the argument but it is bizarre to have a different way that the AF system works depending on which button you use to AF. And it is also a change that appears to be undocumented. I believe it is not an intended change but who knows. Regardless, it doesn't much matter to me either way.