J8 collimation - rainy day is scheduled for next Saturday.

[Igor.Burshteyn]

I have J8 on kiev which is some 5-10cm off (back focus) wide open on minimal distance. I will try to service the lens following instruction on kiev survival site, question is whether I need to add or remove shims, and what can be used for shims?

Thanks in advance!

 

[Xmas]

If you dont have a pin vice and morse drills smaller than the threaded holes you will have to carefully tighten up the grubs and hope. They are made of hot butter so you cannot use any torque, without destroying them. Dont know how Brian does this, magicians never reveal critical spells.

The grubs of the aperature ring are real small and it is simpler if you dont unscrew them so they drop out as they are real easy to lose and real easy to cross thread. A simpler option is to tippex the current red dot and nail varnish a new one, if you are old a nice big triangle is better anyway.

If it is a J8 i.e. no click stops the red dot is best set at minium aperature, it can then overshoot at max aperature, I think this gives the best f stop calibration.

Good luck

Noel

 

[tmessenger]

Add shims to correct for back focus, I use aluminum duct tape it's about .001 thick and can be cut with scissors and stacked as required.

Tim

 

[Igor.Burshteyn]

nice to see you again, Brian 🙂

Thanks for your answers, Brian and Noel. I am going to work on black nose lens that says J8 2/50, has click stops, pretty unobtrusive coating (or no coating at all), plus very strange serial 0162083. I am going to destroy pre-production sample 🙂

 

[Igor.Burshteyn]

Tim, thanks for your answer 🙂

 

[Xmas]

Brian
Thanks
Igor
Are your sure the problem is the lens and not the body mount to film registration?
Noel

 

[Igor.Burshteyn]

Noel -

As I said I have J9 which is spot on on this body, so I concluded it's a lens rather than mount or rf. Though I never tried to shot test with J9 - I just don't get focusing mistakes with J9, even at close distance/f2.8 (I rare shot f2, if at all). Need to shot test @f2? Just to be sure.

 

[ed1k]

J9 uses external bayonet, just a thought. Do you have (or could borrow) other J8 or H103 for testing? Do you feel lens is loose when mounted? Black J8 with such serial# could be an export production - does it have cyrillic or latin letters?

 

[Igor.Burshteyn]

Could it be that just internal bayonet has problems with lens-to-film registration? Even didn't think about this possibility. How to check it? Another J8/H103 sonds good idea.
Lens mounts as it should - by no means feels loosy, opposite - very solid and precise. Lens itself is not black, it's silver with black filter ring (black nose), jupiter 8 is written in cyrillic. In addition there is 2/50 and mentioned serial on front - and that's it.

 

[Xmas]

Igor

A J9 at 2.8 should have shown similar effects as a J8 at 2, if the body registration was the problem, so your are probably ok setting up the J8 to the camera.

If you first set the lens on a star using 3M magic tape (matt tape) or ground glass between the inner rails. And if you need adjustment only use the grub screw and then try it at 1M as detailed in the Kiev survivial site. You should have confidence that it matches the rangefinder, the scale on the heliciod and the body.

You can check the J9 is ok at the same time.

If you run into problems then you can set the grub back into the origonal hole no damage done.

Noel

P.S. If you have a web cam or other digital could you please post a photo of your lens front. Are you in new world or old. It may be simpler sending you a J8M, and have you set your prototype on shelf. Your other option is a 'new' helios if the Ru sellers have any left.

 

[Igor.Burshteyn]

Here it is