Access to the Front Elements of the Nikkor D 40mm f4 for Bronica SLRs

[Dinis]

I was wondering if anyone had any idea how to open up the front of the Nikkor D 40mm f4 for Bronica SLRs. I need to clean some fungus. The rear elements screwed out in a straight forward way. I have the name plate screwed off the front, but I can't work out how to get deeper. There are no retaining rings that I can. Here is a photo. I'd be grateful for any ideas anyone has. Thanks!

 

[Dan Daniel]

Any chance that it is simply dropped in place? Lots of lenses do this- make a shelf and retaining ring, and the glass element is loose. Well, not loose. Usually a very precise fit that needs a little pressure.

Put a few layers of a soft clothe on a table, point lens down, and give a few whacks to the back side to see if it drops out.

 

[moto-uno]

As Dan has mentioned or , if you have a Garmin GPS or something similar that mounts to your windshield with a suction cup ,
(these are actually quite strong and may well fit to the larger front lens) and allow you to pull it out . Peter

 

[Dinis]

Dan and Peter, thanks for the suggestions. I did try the suction cups, but it would not budge at all. I think there is a small black ridge attached to side of the lens that is keeping the first element in place. It seems like there are two threaded surfaces that need to be unscrewed from each other. I just can't work out how to do it.

 

[David A. Goldfarb]

Send it to Frank Marshman. He's the Bronica guy. It's a great lens. I wouldn't want to mess it up.

 

[shutterfinger]

Use a strap wrench https://www.amazon.com/Adjustable-W...1&keywords=strap+wrench&qid=1602369986&sr=8-7 and unscrew the top most ring while holding the lens barrel stationary. The threads of the ring may be sealed with thread locker, acetone will dissolve it. Apply to the threads only.

 

[moto-uno]

Looking at your second picture , is there a very small slot head screw coming in from the side ? It appears to be in the
threaded area closest to the grooved ring . Possibly a more detailed picture would clarify it. Peter

 

[John Koehrer]

Back to the strap wrench. The ring going around the edge of the element may simply unscrew.

 

[Dan Daniel]

Looking at your second picture , is there a very small slot head screw coming in from the side ? It appears to be in the
threaded area closest to the grooved ring . Possibly a more detailed picture would clarify it. Peter

Could be- if you go up from the lower silver part to the largest knurled ring, then right two knurls and a bit more, that could be a set screw in the threaded area just above. If so, check for two more at 120 degrees around.

 

[Dinis]

Thanks to everyone for their suggestions. I did think there might be a set screw on the threaded area. There is a small hole just above the knurled aperture ring. I can see a silver surface behind it, but it is flat with no slot for a screwdriver. It might have been stripped at some point in the past. I'll have to think about drilling it out or just using the lens as is. Thanks to all!

 

[reddesert]

If there is just a hole, maybe there was once a setscrew and now it is gone. I would be cautious about drilling anything. How bad is this fungus really? The lens doesn't look terrible. If it were mine, I might just set it out in the sun to kill the fungus by UV light and then use it as is. Sometimes, even if you can get lens assemblies apart, you can't get the groups within the assembly out.

 

[Dinis]

Just an update that I was finally able to get the front element opened and cleaned on this lens in case anyone needs to know how to work on the same lens. The set screw on my lens was in fact stripped. I was able to drill it out with a tiny drill bit and then order a small strap wrench to open it. All of the threads in the front element assembly were locked with loctite or some other thread locker. So those needed some acetone and heat to get them to loosen. The top ring in the lens holds the entire front lens assembly in place. It lifts out and then you can access each of the lens elements by unscrewing them. It's pretty obvious how to proceed element by element after they are all out. Acetone is needed to loosen the threads for each element as well as they were all locked. Thanks again to everyone who had suggestions as that helped me figure it out.

 

[moto-uno]

That's the good news we appreciate hearing back about , thanks for the follow up . Peter