Any special tips or resources for disassembling a 50mm Sekor C F4.5 RB67 lens?

Certain Exposures · Oct 24, 2023

Question:

Have any of you who aren't professional camera repairmen attempted this before? How did it go for you? What special tools or resources did you use? I found a video where someone disassembled a 50mm F4.5 RB67 lens, but it was a model that preceded the Sekor C.

Context:

I have a 50mm Sekor C F4.5 lens that I need to disassemble to remove oil from the blade mechanism.

I bought the lens untested at a fair discount. I tested the lens with film, and it is functional. However, the shutter blades do not close properly, so I have slow speeds at every setting.

A professional repair would not be practical because the lens' glass has flaws. I'm still investigating how much of an impact those flaws have on the negatives. Still, I can shoot around both issues, so this slow speed problem isn't necessarily something I have to fix. I'm mainly gathering information to see if it's worth trying myself.

ic-racer · Oct 24, 2023

Aperture repair can be tricky, especially if you have never done it before.

Here is a good video. At the 1 hour mark he has the shutter out, from there usually one removes the mechanism (791-0001) from the shell (791-003), revealing the shutter blades, (which will fallout) and the aperture mechanism, which can be disassembled and cleaned.

BrianShaw · Oct 24, 2023

If the aperture blades are oily then you really need to think about how that happened. Cleaning them might not be all that is needed.

ic-racer · Oct 24, 2023

Since the aperture blades are the last thing left after the entire rest of the lens is disassembled, usually any other issue will be addressed on re-assembly.

BrianShaw · Oct 24, 2023

Precisely. My point is that the task required might be much closer to a full overhaul than just accessing the aperture blades and wiping them clean.

Certain Exposures · Oct 25, 2023

Thanks, @ic-racer and @BrianShaw . I have to reflect on this some more. I will watch the video you linked.

Unfortunately, the seller doesn't know any details about the lens' history. I've been looking around for a decent 50mm Sekor C at a reasonable price. Many are selling for a lot despite noticeable flaws. Since mine "works," I'll keep enjoying it within its limitations until I find either a replacement or get the courage to turn it into a DIY project.

Neil Grant · Oct 25, 2023

an overhaul of the 50mm C will be rather more complex than that of the 127mm because of the floating element system - whose helical thread is probably the source of oil on blades. Could you unscrew the rear group to get to the back of the diaphragm?

Certain Exposures · Oct 26, 2023

Neil Grant said:
an overhaul of the 50mm C will be rather more complex than that of the 127mm because of the floating element system - whose helical thread is probably the source of oil on blades. Could you unscrew the rear group to get to the back of the diaphragm?

Thanks, I am not sure if I can. I will have to look into it. I emailed a source that might have more information.

Alex Varas · Oct 29, 2023

If I remember correctly the RB67 lenses are very similar to Kowa ones in terms of construction.

I made a video of mounting back a Kowa 85 frommthe shutter blades and you might find useful for dismantling your 50mm C

Certain Exposures · Oct 29, 2023

Alex Varas said:
If I remember correctly the RB67 lenses are very similar to Kowa ones in terms of construction.

I made a video of mounting back a Kowa 85 frommthe shutter blades and you might find useful for dismantling your 50mm C

Thanks, Alex. I'll take a look.

Certain Exposures · Oct 29, 2023

Question for the moderators:

Could we move this thread to the "Camera Building, Repairs & Modification" forum ? I didn't realize there was one for that until now.

MattKing · Oct 29, 2023

Certain Exposures said:
Question for the moderators:

Could we move this thread to the "Camera Building, Repairs & Modification" forum ? I didn't realize there was one for that until now.

Thanks for the suggestion - consider it done.
Just as a heads up - the best way to make something like this happen is to Report your opening post, and make the request there. That way it automatically comes to the attention of all moderators.

Certain Exposures · Oct 29, 2023

MattKing said:
Thanks for the suggestion - consider it done.
Just as a heads up - the best way to make something like this happen is to Report your opening post, and make the request there. That way it automatically comes to the attention of all moderators.

Thank you - will do.

Any special tips or resources for disassembling a 50mm Sekor C F4.5 RB67 lens?

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