Jupiter-8 internal cleaning - disassembly question

[Steve Goldstein]

My recently-acquired Type 4 Jupiter-8 (black barrel, green lettering) has what looks like a few hairs inside that I'd like to clean out. I've been looking around for disassembly info but haven't found anything specific to this version or the very similar Type 3. I did find kosbik84's YouTube video for the Type 1 lens, but as there are some mechanical differences between Type 1 and Type 4 I'd like to know if disassembly of these two versions is the same. Anyone?

Thanks!

All are 50mm f/2 LTM lenses. Physical differences are:

Type 1 = silver barrel, infinity lock
Type 2 = silver barrel, no infinity lock
Type 3 = black barrel, white lettering on focus scale
Type 4 = black barrel, green letting on focus scale

 

[Steve Goldstein]

To follow up and answer my own question, some additional web searching suggested simply unscrewing things, so I tried it and it worked.

Grasp the front of the the lens (ahead of the aperture ring) in one hand, the base in the other, and twist. It's a standard right-hand thread. The entire optical assembly unscrews from the focusing assembly. Be careful not to lose any internal shims when you remove the optical block, my lens had two of them. Also, note the orientation of the optical block to the focusing base for reassembly.

With the optical block out the rear group can be unscrewed, again standard right-hand threads. This was all I needed to be able to blow out the dust. Reassembly is the reverse, as they say. Total elapsed time was under 5 minutes, not including nearly an hour of searching and watching YouTube videos of the Type 1 and Type 2 lenses

 

[Ron (Netherlands)]

Well done. Once serviced these are very nice lenses; I've cleaned several (also the Jupiter 3 - f1.5) and they become especially attractive in use when you clean out the old lube from the threads and put in some modern lube. The black ones are the better ones IMHO (jup 8 as well as jup 3).

Here's some more info:

http://www.pentax-manuals.com/repairs/j8service.pdf

http://helino-photo.blogspot.com/2016/01/how-to-clean-and-re-grease-two-jupiter.html

https://tomtiger.home.xs4all.nl/zenrep/indus.html