Nikon 5cm f2 LTM Loose Aperture fix?

[Ong]

So I've finally bit the bullet and obtained a the 5cm/2, a slightly used thing with optics in great condition. My only gripe is that the aperture seems loose and does have a tendency to move out from the aperture I've set.

Being the clickless version, is there any way to tighten her up as a DIY job (or any instructions?)

 

[jonmanjiro]

I've never worked on this particular RF Nikkor so cannot help with specific instructions, but the RF Nikkors I have worked on have all been very straightforward to disassemble and repair. So if you've got the right tools and are game, I'd say give it a go. I reckon a dab of grease in the right spot to provide some friction on the aperture ring would be all you'd need to fix it.

It might help if you could post some photos of the lens, but I'm guessing you'd need to go in through the back by removing the retaining ring around the rear element, removing the focusing mechanism (watch for shims between the optical cell and the focusing mechanism), then removing the aperture ring sleeve and placing a dab of grease in-between it and the optical cell. Hopefully someone with experience working on this lens will chime in and clarify for us.

 

[Ong]

Good to hear from you Jon!

Pretty much where the red circle is (the aperture ring), it just feels as if it is lacking any resistance which sometimes results to a slight rub changing the aperture accidentally

I was more so hoping that it would be turning some screws just so there's a bit more resistance and feedback. But it seems like a teardown may be in order.

 

[John E Earley]

How is the transition to close focus. Smooth or a bit difficult.

 

[jonmanjiro]

I was more so hoping that it would be turning some screws just so there's a bit more resistance and feedback. But it seems like a teardown may be in order.

You could try tightening the screws on the aperture ring (there's one pictured just below the F2 engraving in your photo). No harm in that. But I think they are just for holding the aperture ring in a position correctly aligned with the actual aperture position i.e. when the aperture is at F2, the aperture ring also shows F2. I think you're going to have to do a partial teardown to solve your loose aperture problem though. The good news is that they're very simple lenses to work on, especially so in your case because you don't need to disassemble the focus helicoid or open up the optical cell.

 

[nhchen]

I don't know how similar they are but in old zeiss and russian lenses you have to put some grease in where the aperture ring turns to stiffen them up slightly.
Nathan

 

[Ong]

How is the transition to close focus. Smooth or a bit difficult.

Not too stiff, just requiring a bit more force over regular focusing to get over the "transition warning point" where the rangefinder will lose coupling but otherwise smooth.

You could try tightening the screws on the aperture ring (there's one pictured just below the F2 engraving in your photo). No harm in that. But I think they are just for holding the aperture ring in a position correctly aligned with the actual aperture position i.e. when the aperture is at F2, the aperture ring also shows F2. I think you're going to have to do a partial teardown to solve your loose aperture problem though. The good news is that they're very simple lenses to work on, especially so in your case because you don't need to disassemble the focus helicoid or open up the optical cell.

Looks like your theory on the screws holding the aperture ring is correct. Any suggestions on guides to follow/where to apply grease or the type of grease to apply?

 

[nhchen]

I found a website showing how to partially disassemble the nikon rangefinder version of the lens, don't know if that will help? That's assuming the construction is similar apart from the focusing mechanism in the ltm version.
http://www.nicovandijk.net/rflensrepair.htm

nathan

 

[jonmanjiro]

Looks like your theory on the screws holding the aperture ring is correct. Any suggestions on guides to follow/where to apply grease or the type of grease to apply?

It was certainly the case for this S-mount W-Nikkor 3.5cm F1.8 2005 (converted to M-mount by MS Optical R&D) and this S-mount Nikkor-S 5cm F1.4, so I'm fairly confident the same would apply to your lens.

Lucky for you, you don't have to remove the aperture blades as getting them back in place is a real test of your patience!

As I mentioned in my first post above, I think you have to go in from the back. I'd use S-30 grade helicoid grease but a reasonably heavy synthetic bicycle grease should do the trick. You only need a tiny bit though.

* Loosen and remove the retaining ring around the rear element
* Remove focus helicoid. I'm guessing it will just lift straight off after you've removed the retaining ring. That will leave you with the aperture ring sleeve attached to the optical cell.
* The next step is to remove the aperture ring sleeve and apply a bit of grease on its underside where it comes into contact with (slides around) the optical cell, but I can't be sure how to remove the aperture sleeve without seeing whats underneath the focus helicoid. It should be fairly self evident though once you can see it.