CV Lens Experts: Help!

[Bike Tourist]

I received my 40mm Nokton to go with my new/old Bessa T yesterday.

The shade, when bayonetted on, was so loose it rattled. I could not use it confidently, thinking it would just fall off at any time. I've temporarily shimmed it with electricians' tape — not an elegant solution.

There are three thin slots around the perimeter which look like they could be enlarged by prying with a knife, making the shade fit tighter, but I don't want to break it.

Has anyone else encountered this problem?

 

[pvdhaar]

Had a similar experience the other day with the 25/4. It hung under my coat with the (screwmount) shade and the cap mounted. I was sure I had them tightened, but guess what.. At a certain moment I heard a distinct 'clink' and there the cap and shade were rolling over the pavement. Worked themselves loose.

I put it back on tight, but when checking later, they were loose again. My solution is to put a single round of plumbers tape (that is the kind that doesn't have a sticky side, it's used to seal screw fittings on faucets, taps etc.) on the thread.. Easy to remove too without leaving any gum.

 

[Bike Tourist]

Peter —

I think I have a solution: Silicone sealant. I will apply a little of this on the bayonet flange surfaces and it will set up and keep things tight and rattle-free. If I want to remove it, a little extra effort will dislodge it. The silicone can be removed without leaving any trace.

I'm also going to use it to cement a diopter that I cut down from an old Nikon eyepiece to the 40mm viewfinder. I will have a crystal clear viewfinder (for my eyes) and still be able to remove it later if necessary.

Thanks for your response.

 

[ferider]

If you look around the slit on the perimeter of the shade, you will see
a locking nut at some point (which lock the shade in place). If you bend the
slit together very slightly with some needle nose pliers at that point your
problem will be solved.

Roland.

 

[Bike Tourist]

Thanks, Roland, I did as you suggest but it didn't seem to help. Maybe I didn't apply enough pressure. I'll keep working with it.

 

[Bike Tourist]

Judging by the response to this one, no one cares anyway, but I might as well follow up.

I have a complete picture taking RF camera now.

1. Bessa T with light leak through the back door window.
Solution: Put black electricians tape over it. Looks good. 100% effective.

2. Viewfinder blurry to my eyes.
Solution: Take an old rectangular Nikon +2 correction diopter and cut it down so that just a small plastic frame surrounds the glass. Cement on the viewfinder with silicone. Now, I have a nice clear view. The diopter will come off along with the silicone if I ever want to sell it.

3. Lens shade loose and rattles.
Solution: Apply a little silicone cement to the bayonet surfaces. It's rock solid and rattle-free now. I never remove my lens shades since I consider them part of the lens. but if I ever want to — ditto the viewfinder comments above.

 

[jmilkins]

maybe it's not that no one cares but that what you describe is not too common.

My CV 40 hood (pre owned) was missing two of the three little screws, so the 2 parts of it used to rattle - but my fix was easier.

Good to hear you have working kit and have solved the issues.

 

[ferider]

I do care, Dick, and two out of the three Noktons that I have/had had a rattling shade, but for me my fix worked.

I'm glad you fixed the issues, T+40 is a killer combo.

Best,

Roland.

 

[Bike Tourist]

Hey Roland, I didn't mean to be so negative! Thanks for your input. In my case there was just a very loose fit between the bayonet flanges. I think tolerances are a little looser in the Cosina organization and sometimes the tolerances all add up in one direction instead of canceling out.

But at the prices of CV gear I can live with it!