WTB: Jupiter-8 in bad condition

[Spyderman]

Hi,

maybe you noticed my thread in the Repair section, but if not, let me sum it up:

I have an older 35mm cine lens Cooke speed panchro 75mm f/2 without mount (i have only the optical block) and I'd like to transplant it into LTM mount - maybe even RF coupled (we'll see if I can do that).

For this I need the focus mount(s) from Jupiter-8 - especially the version where the front rotates when you focus (pictured below). It's the least desired version in terms of usability, but for this purpose it's the best, because the RF coupling ring rotates as well, and to make it RF coupled I'd need make a "ramp" on the RF coupling ring.

So, if you have such lens in bad condition (scratches, fungus, bent filter thread... anything) or only the focus mount (optics isn't important) then do let me know.

 

[nzeeman]

maybe its easier to convert it to contax mount. it is automatically rf coupled.

 

[Kim Coxon]

I will have a look and PM if I can do. May be a week or 2. As to the RF coupling, I doubt you will be able to do it using an FSU body or any other which relies on a helix for the focus tab/ring. You would have to machine a new set of threads and convert it to a double helix like the J9. A better conversion would be to use something like one of the Canon bodies with the focussing "tongue". These ride on a sloping ring and changing the gradient would be easier though the calculations might prove difficult. With the J8 mount, you would have to use a ground glass screen the focus on objects at different distances and use this to make a new focus scale.

Kim

 

[rxmd]

I'm leaving Uzbekistan on Saturday and will be pretty busy till then, but if I can find one until then I'll keep you noticed. It's a pity you didn't post this earlier, I could have brought you ten or so dead J-8's from last weekend's flea market 😉

Philipp

 

[Kim Coxon]

Philipp,
If you come across any cheap J8's etc that can be salvaged, I would be quite happy to CLA them and then pass them on to RF members at "cost". There seems still to be quite a demand but it is not worth doing if I have to pay shipping costs on each one.

Kim

I'm leaving Uzbekistan on Saturday and will be pretty busy till then, but if I can find one until then I'll keep you noticed. It's a pity you didn't post this earlier, I could have brought you ten or so dead J-8's from last weekend's flea market 😉

Philipp

 

[Spyderman]

I will have a look and PM if I can do. May be a week or 2. As to the RF coupling, I doubt you will be able to do it using an FSU body or any other which relies on a helix for the focus tab/ring. You would have to machine a new set of threads and convert it to a double helix like the J9. A better conversion would be to use something like one of the Canon bodies with the focussing "tongue". These ride on a sloping ring and changing the gradient would be easier though the calculations might prove difficult. With the J8 mount, you would have to use a ground glass screen the focus on objects at different distances and use this to make a new focus scale.

I was planning to use it on Bessa. I know it wouldn't work with FSU bodies.

My source of inspiration is the set of lenses for Leica CL which have single helical focussing, and a "ramp" on the RF coupling ring.

In the worst case I could simply make another scale on the focus mount, focus using RF, read the original scale (for 50mm) and then refocus using the second scale (for 75mm). For this any Jupiter-8 focus mount would be usable.

 

[rxmd]

Kim,

If you come across any cheap J8's etc that can be salvaged, I would be quite happy to CLA them and then pass them on to RF members at "cost". There seems still to be quite a demand but it is not worth doing if I have to pay shipping costs on each one.

That's a very nice idea and quite generous. As I said I'm not sure how much I can manage this time given that I'm short on time. However either way I'll be back in Uzbekistan in February or March or so; if I don't manage to get anything now maybe we can discuss this again before I go the next time?

Philipp

 

[januaryman]

This caught my eye. I have a question -- I recently won a Jupiter 8 on that auction site and it works well indoors and in hot weather. As the temp dropped, so did my ability to switch apertures on this lens. At one pioint it just seized up until I could get it inside and warmed up. So - do I ditch this and get another from a Fedka type place, or do I send it to Fedka for $55 to get a CLA? Seems as costly to clean as to buy.

Jim

 

[Kim Coxon]

If you do the service yourself, it will cost about 25c for the amount of lube etc you will use. 😉

Kim

This caught my eye. I have a question -- I recently won a Jupiter 8 on that auction site and it works well indoors and in hot weather. As the temp dropped, so did my ability to switch apertures on this lens. At one pioint it just seized up until I could get it inside and warmed up. So - do I ditch this and get another from a Fedka type place, or do I send it to Fedka for $55 to get a CLA? Seems as costly to clean as to buy.

Jim

 

[januaryman]

Kim - any links on an explanation on how this is done?

 

[Kim Coxon]

Full instructions on my website. 😉

http://pentax-manuals.com/repairs.htm

Kim

Kim - any links on an explanation on how this is done?

 

[Gabriel M.A.]

Philipp,
If you come across any cheap J8's etc that can be salvaged, I would be quite happy to CLA them and then pass them on to RF members at "cost". There seems still to be quite a demand but it is not worth doing if I have to pay shipping costs on each one.

I vaguely remember seeing some Russian (or Ukrainian?) seller on ePrey that would sell lots (as in plural "lot" not "a bunch of") of Jupiters and 53mm Helios lenses.

Perhaps we could all pool in? Is it more expensive to have it shipped to the U.K. than the U.S.?

 

[raid]

I have several seen exotic lenses for cine. Is there a chance to hack any of them into LTM?

 

[januaryman]

@ Kim - Thanks very much for the link. The manuals are great and I think that I might be able to do it -

Two further questions -- Do I get rid of the old grease with Ronsonol? And where in the US can I get the lubricant needed for this job and what is it called? Thanks again.

 

[rxmd]

Hi Ondrej,

sorry, I won't manage it this time, I've run into some organisational trouble here that will keep my busy this afternoon so I can't meet my dealer. I hope Kim has something for you!

Philipp

 

[Spyderman]

Never mind Philipp, I'll look for something locally...

januaryman: you can get the white lithium grease in a bicycle shop. I'm sure you can get there also some kind of degreaser - I usually use citrus degreaser to remove the old dried grease, especially on the internal parts of lenses (helicals). Toothbrush is a good tool to remove the grease from helicals.

 

[januaryman]

Thanks, Ondrej. I'm weighing my options. I may just keep it as it is - works 100% indoors, in summer. When it gets cooler out, it just balks. I'm afraid of mucking it up worse... Thanks to everyone who helped!