Nikon FM3a viewfinder problem

[Pete_Myers]

Dear Group:

I have a "new" Nikon FM3a that came out of Japan. Exceptionally minty, it looks like it was never used.

Today, I had it out in the field for the first time. I noticed a blue chromatic band around the edge of the viewfinder. The viewfinder image is crisp, and everything seems to be functioning normally, but it would seem there are color aberrations at times in the finder.

Any one experience something similar with an FM3a or another camera? Not sure if there is something wrong with the focusing screen (like oil) or an optical mis-alignment. I would appreciate some hints! I would hate to send it off to repair if it is something I can take care of myself

Pete

 

[Range-rover]

Check for lens flare, or switch another lens, when I had a FM2 I could of sworn I had
that problem once. Maybe you have to reset the screen.

Range

 

[mikemc_photo]

Does it have a "bright Screen?

The other thought is light coming in to the VF from the eyepiece...a eyecup will stop this

 

[Pete_Myers]

The FM3a has the normal K3 screen that came with the camera. Shielding the eyepiece does not seem to be helping. The lens I have been using is the Zeiss ZF.2 2/50, which has extremely low CA.

Around the edge of focusing screen and the mask for the viewfinder is a blue line---it is just really odd. I have never seen this in any camera I have owned over the past thirty years.

Pete

 

[mfogiel]

This is strange, I have two FM3A's, and I have never seen anything like that, with the Makro Planar 50 or any other lens. On the other hand, both my FM3A's exhibit a heavy back focus with all lenses - I think it is a factory defect, so check your camera as well.

 

[daveleo]

I just checked my FM3A. Never noticed it before, the around the edge of the frame in the viewfinder window is an EXTREMELY thin blue line. Unnoticable unless you are looking hard to see it, but it's there.

Have no idea what it is, but I will guess that it has to do with optics around the very edge of the focusing screen. It is a sharp line, not a blur.

Is your focusing screen seated down properly? Is there a shim under it ?

 

[Pete_Myers]

Hi Dave and friends:

Dave, glad to hear that your seeing it in your viewfinder! That means it is likely "normal."

I would like to know about the back focus issue and the magic shim that I may or may not have on my unit.

Thank you all for your kind replies. I am grateful to you.

Pete

 

[DavidKKHansen]

I just checked my FM3A. Never noticed it before, the around the edge of the frame in the viewfinder window is an EXTREMELY thin blue line. Unnoticable unless you are looking hard to see it, but it's there.

Have no idea what it is, but I will guess that it has to do with optics around the very edge of the focusing screen. It is a sharp line, not a blur.

Is your focusing screen seated down properly? Is there a shim under it ?

Just got my FM3A now... I have to really look hard to see the blue color along the edges. This seems to be a normal characteristic of the FM3A.

Carry on, nothing to worry about 😎