Weird D700 focus screen problem...

[scott_mcleod]

My D700 has a strange "blurry band" that runs vertically almost smack through the middle of the frame (very slightly to the left of the center focus indicator). It's pretty subtle but does get in the way when trying to use manual focus. My D300 screen is completely uniform with no irregularities whatsoever.

Has anyone else noticed this? You have to look very closely to see it, and the subject has to be textured and fairly contrasty, but when moving the camera slowly over something that has a lot of detail, like a tree with foliage, it becomes pretty obvious. I am considering buying a stock replacement screen (as a spare part) and swapping it to see if it has the same problem. I tried an aftermarket screen but it had an entirely different (design) "issue" that made it unusable.

This camera has already been back to Nikon to try and sort out a related issue - the image in the VF is slightly OOF when the AF has locked (correctly), and when focusing manually, when the VF is sharp, the captured image is slightly OOF. This is a problem that seems to affect lenses over 50mm much more than shorter ones.

Any advice on this topic would be greatly appreciated! I ADORE the file quality from the D700 (my D300 is very noisy, and the way it shoots in 14-bit mode is rather underwhelming) but this VF/focus issue is driving me nuts to the point I am thinking of selling it.

Regards,
Scott

 

[RossWM]

I know about how frustrating these things could be! I have had a 'mark' on the focusing screen similar to what you have. I believe it was a result of an already very carefully cleaning of the focusing screen. As the screen's matt surface is very delicate, even an extremely slight mark will show up when veiwing thru the VF.

A replacement of the screen at Nikon fixed it. I believe you can't just buy the focusing screen, but it needs to be replaced at Nikon as a repair job like in my case. So it's best to never touch the screen's surface.
Hope this help.

 

[scott_mcleod]

I think you're right about it being a Nikon repair job - even though the screen is very easy to remove if you have the right tool, I can't find a stock replacement for sale anywhere - unlike the D3/s/x which has user-replaceable screens as an option.

Looks like another trip back to Nikon for the D700...

Scott

 

[Martin Zimelka]

...its not the focus screen.
Its where the two part of the prism are put together.

I have the same issue with my D700. Very annoyin, but Nikon refuses to see an issue. Denial.

 

[scott_mcleod]

That's extremely interesting - I never thought of the prism as being made in more than 1 piece. If that is the cause of what I'm seeing, as you say, it's not something that can be fixed at any price

Thanks for the tip
Scott

 

[PMJD42]

Interesting. I don't see it on my D700, but that might be because my eyes are going.

 

[RossWM]

On the topic of prism, I think the prism in the camera is made of a solid crystal like material, and should be in one piece.

If you are talking about a possible visiible line in between, it will be the the result of the joint where two mirror surfaces above the prism meet. This joint is there and should not be quite visible under normal use. But if you look hard enough, there could be a trace of it. If the line is very obvious, there is certainly something wrong; and fixing it will mean replacement of the whole penta-prism/VF section!

 

[scott_mcleod]

On the topic of prism, I think the prism in the camera is made of a solid crystal like material, and should be in one piece.

That's what I always thought, but you never know...

If you are talking about a possible visiible line in between, it will be the the result of the joint where two mirror surfaces above the prism meet. This joint is there and should not be quite visible under normal use. But if you look hard enough, there could be a trace of it. If the line is very obvious, there is certainly something wrong; and fixing it will mean replacement of the whole penta-prism/VF section!

And there's the problem... whether the Nikon tech who examines the camera can see it, and if so, whether they consider it a problem worthy of fixing under warranty!

Scott

 

[Martin Zimelka]

I cant comment exactly how the prism is made, but the problem is not consistent from D700 to D700... I had a loan unit which was perfect, but mine had that bloody blurry band.

Coming from F4 and F5...I know that the F4's prism was glued together using a resin of sorts. Not sure if it applies to the D700, but pretty sure its the prism.

The prism can be replaced, but I cant imagine that to be a cheap exercise...

I just let it be, as much as it irritates me, because it will be pointless for me attempt running this past Nikon service here in South Africa.

Everything is always in spec, even if there is something wrong.
Pattern noise, focus point alignment, prism, etc...

 

[scott_mcleod]

I cant comment exactly how the prism is made, but the problem is not consistent from D700 to D700... I had a loan unit which was perfect, but mine had that bloody blurry band.

That would explain why it's not a widely reported problem - but yeah, it sure is annoying, especially as it's right where I need maximum clarity for MF lenses. The fact that my old D300 snaps perfectly into focus with the stock screen is just depressing.

Coming from F4 and F5...I know that the F4's prism was glued together using a resin of sorts. Not sure if it applies to the D700, but pretty sure its the prism.

The prism can be replaced, but I cant imagine that to be a cheap exercise...

I have a feeling that the cost of the prism plus the labour required to remove and replace it is why, as you say below, it would be determined to be "within spec" no matter what

I just let it be, as much as it irritates me, because it will be pointless for me attempt running this past Nikon service here in South Africa.

Everything is always in spec, even if there is something wrong.
Pattern noise, focus point alignment, prism, etc...

You are not alone there... sounds just like the story with my 12-24DX - a $900 paperweight that I practically gave away, a months-long debacle over a severely decentered 35/2, and the mis-calibration between the VF and AF on my D700.

I dunno what to do. If I was happy to always rely on AF, even when it looks wrong, or use live view, then it would be okay. But I have a ZF 25/2.8 that is just a beaut for WA landscapes, and magnified LV is not often practical when using the camera hand-held outdoors. What is really frustrating is that I'm not expecting some untold miracle from the camera, just that I ought to be able to get it do what it's supposed to do without resorting to awkward work-arounds...

 

[Martin Zimelka]

I dont know if your issue is worse than mine or not...however, seeing that there is little anything can be done, I just left it.
I know what to look out for in the next one...write it off to experience.

My D700 has been in to Nikon so many times, that I have effectively lost about two months of shooting with it.

They replaced my DG-PCB board, and a month later my sensor.

I had vertical pattern noise issues than not even the tech guys could see...but comparing two and three D700 side by side, I clearly had an issue.

The effort it took to get Nikon to replace all those things was something I'm not keen on going through again... My situation was helped due to Nikon cocking up my 14-24 the year before, to the point that it had soft corners until f/16 and the focus motor failed constantly... I made quite a big fuss about that, and I wonder if they treat me better because of it. Not really fair.

I have a 50mm f/1.8 that has clear decentering when shooting infinity bellow f/5.6.

Its been up to Nikon and they can't determine any fault with it. Its frustrating to say the least. I have stopped buying Nikon glass until I can afford to buy such expensive lenses with that level of either QC sample variation or failure rates.

 

[cfbrobak]

Hi Scott,

Not exactly about your problems, but then again:

Have you made sure the view finder diopter adjustment is set correctly for your eyes? I always use manual focus and have found it very, very important that this adjustment is correct. You could make a few experiments with the adjustment control. At least it might take care of the problem with the green light not corresponding to the view finder image.

I am also using a D700.

Regards,
Claus

 

[scott_mcleod]

Hi Claus,

Unfortunately I have checked the diopter with numerous tests, on and off tripod, and the best setting for me seems to be zero. The difference between how the VF looks when the AF has locked and the best manually-focused VF image (which is in fact OOF as viewwd by the sensor) is really quite marked, and I think it would require changing the number/thickness of the shims that go under (actually on top of) the focusing screen, but I have yet to find a source for these shims. Focusing manually then switching to magnified Live View shows the problem very well...

Regards,
Scott

 

[Martin Zimelka]

Does your D700 have shims under the focus screen?
I have not inspected my D700 yet, but I don't recall seeing shims in my D2x.
Are there supposed to shims there?
On which side are they? Mirror or prism side?

Hi Claus,

Unfortunately I have checked the diopter with numerous tests, on and off tripod, and the best setting for me seems to be zero. The difference between how the VF looks when the AF has locked and the best manually-focused VF image (which is in fact OOF as viewwd by the sensor) is really quite marked, and I think it would require changing the number/thickness of the shims that go under (actually on top of) the focusing screen, but I have yet to find a source for these shims. Focusing manually then switching to magnified Live View shows the problem very well...

Regards,
Scott

 

[scott_mcleod]

Does your D700 have shims under the focus screen?

Yes, it has 2. Both are very thin; the thicker one is brass-colored and the extremely thin one is copper-colored.

I have not inspected my D700 yet, but I don't recall seeing shims in my D2x.

Unlike the screen, the shims don't always fall free of their own accord when you release the catch (especially the first time; mine now come out with the screen), so your D2x may have had them, and they just stayed in place (but I could be wrong about that camera, not having fooled around with one myself!)

Are there supposed to shims there?

Apparently so; they are installed to tweak the path length difference between the screen and the AF sensors (which have their own mirror). Using the eccentric screw which is referred to everywhere adjusts the angle of the main mirror, but not the pivot point, so if you take that route you will get back/front-focus vertically across the viewfinder

On which side are they? Mirror or prism side?

They are on the prism side. The thicker one goes over the thinner (viewed with the camera held upside-down), presumably to prevent damage when changing / replacing screens - it's unbelievably thin.

Mine backfocuses slightly when focused manually. Some experimentation with the shims indicates I need either more and/or thicker shims to correct the problem.

HTH,
Scott

Hi Claus,

Unfortunately I have checked the diopter with numerous tests, on and off tripod, and the best setting for me seems to be zero. The difference between how the VF looks when the AF has locked and the best manually-focused VF image (which is in fact OOF as viewwd by the sensor) is really quite marked, and I think it would require changing the number/thickness of the shims that go under (actually on top of) the focusing screen, but I have yet to find a source for these shims. Focusing manually then switching to magnified Live View shows the problem very well...

Regards,
Scott

 

[Martin Zimelka]

Ok, thats interesting.

Yeah, thicker shims that move the screen further away from the prism will correct for back-focus.

I had to calibrate my Rolleiflex recently for back focus, but that seemed like an easier thing to do because the tolerances aren't as fine.

Good luck.