scorpius73
Well-known
My J8 needs to be adjusted. It goes past f2 when wide open and the focusing ring is very stiff. Got any leads on who can do the job and ball park figure for price? Thanks.
Dez
Bodger Extraordinaire
You can, and the cost will be nothing. It is an easy fix.
I can walk you through it if you wish, or I am fairly sure the method is detailed on the forum in a few places.
There are several different versions and the means of getting at the focus mount is different for the various versions. Is this a black one? If a silver one, is it the version with three screws holding the mount onto the back of the lens?
Here is how to service the aperture. Work with the aperture ring is the same for the different versions. I will assume you may want to re-lube the aperture ring as well. The position of the aperture ring relative to the index is determined mainly by how far the lens optics are screwed into the focusing mount. Assuming the displacement is small, it can be easily corrected without any significant change in the focusing of the lens.
The lens optic block unscrews from the focus mount, but often requires a lot of persuasion. First set the aperture wide open, and grip the front of the lens firmly with a rubber sheet for good traction. The aperture is set wide open, as sometimes when doing this you end up turning the aperture more than the front of the lens, and if you turn the aperture ring too far you may damage things. For the Kiev version, the lens group can be removed from the lens mount by undoing a ring at the back.
With the lens unscrewed, you can see shims around the lens block. Set these aside and don't lose any. The aperture ring is retained by a brass ring around the lens, secured with a setscrew. Note its position carefully, as it is necessary to return it to the exact same position when putting things together again. Unscrew this ring completely. Undo the three tiny setscrews around the aperture ring, and it will pull off the back of the lens. Note its position carefully too.
Almost always, a stiff aperture is caused by congealing of the grease under the aperture ring. Clean the crud out of the inside of the aperture ring with just about any solvent- turpentine, varsol, lighter fluid, etc. Also clean the lens barrel under the aperture ring, but be careful not to get the cleaning fluid inside, or it will eventually fog the lens.
Apply some light grease to the inside of the aperture ring. I use white lithium grease, but many people prefer something heavier like wheel bearing grease. The lithium grease is light, and may not give the same buttery smoothness to the aperture ring, but it won't freeze into immobility in the winter like the heavier grease either. Put the aperture ring back on and the setscrews back in. Screw the brass ring back on (to its exact original position, or you will mess up the focus. Generally this is almost as far as it will screw in, and the dent from the securing set screw is usually very obvious, so it is easy to get this right. Make sure you remember to put the shims back in.
Screw the lens back together, and see if you can line up the aperture with the index properly while it is screwed in tight. If it refuses to align, loosen the setscrews in the aperture ring, and rotate it a bit so the numbers align properly.
There are several tricks for dealing with the stiff focus mount, and some are quire easy, but it will depend on the version of J8 you have. Please let me know if you want to give it a try.
Cheers,
Dez
I can walk you through it if you wish, or I am fairly sure the method is detailed on the forum in a few places.
There are several different versions and the means of getting at the focus mount is different for the various versions. Is this a black one? If a silver one, is it the version with three screws holding the mount onto the back of the lens?
Here is how to service the aperture. Work with the aperture ring is the same for the different versions. I will assume you may want to re-lube the aperture ring as well. The position of the aperture ring relative to the index is determined mainly by how far the lens optics are screwed into the focusing mount. Assuming the displacement is small, it can be easily corrected without any significant change in the focusing of the lens.
The lens optic block unscrews from the focus mount, but often requires a lot of persuasion. First set the aperture wide open, and grip the front of the lens firmly with a rubber sheet for good traction. The aperture is set wide open, as sometimes when doing this you end up turning the aperture more than the front of the lens, and if you turn the aperture ring too far you may damage things. For the Kiev version, the lens group can be removed from the lens mount by undoing a ring at the back.
With the lens unscrewed, you can see shims around the lens block. Set these aside and don't lose any. The aperture ring is retained by a brass ring around the lens, secured with a setscrew. Note its position carefully, as it is necessary to return it to the exact same position when putting things together again. Unscrew this ring completely. Undo the three tiny setscrews around the aperture ring, and it will pull off the back of the lens. Note its position carefully too.
Almost always, a stiff aperture is caused by congealing of the grease under the aperture ring. Clean the crud out of the inside of the aperture ring with just about any solvent- turpentine, varsol, lighter fluid, etc. Also clean the lens barrel under the aperture ring, but be careful not to get the cleaning fluid inside, or it will eventually fog the lens.
Apply some light grease to the inside of the aperture ring. I use white lithium grease, but many people prefer something heavier like wheel bearing grease. The lithium grease is light, and may not give the same buttery smoothness to the aperture ring, but it won't freeze into immobility in the winter like the heavier grease either. Put the aperture ring back on and the setscrews back in. Screw the brass ring back on (to its exact original position, or you will mess up the focus. Generally this is almost as far as it will screw in, and the dent from the securing set screw is usually very obvious, so it is easy to get this right. Make sure you remember to put the shims back in.
Screw the lens back together, and see if you can line up the aperture with the index properly while it is screwed in tight. If it refuses to align, loosen the setscrews in the aperture ring, and rotate it a bit so the numbers align properly.
There are several tricks for dealing with the stiff focus mount, and some are quire easy, but it will depend on the version of J8 you have. Please let me know if you want to give it a try.
Cheers,
Dez
Bill58
Native Texan
...........or if you're not up to doing yourself, Send it to Yuri @ Fedka.com in NYC. His tech guy does a fine CLA.
tbhv55
Well-known
@Dez, with apologies to the OP for jumping in here, I'd be very grateful for absolutely any information on how to overhaul a J-8. I have one which has the opposite to scorpius73's problem: a loose focus ring. It could probably also do with a general CLA while I'm at it.
Is this a reasonably straightforward task for someone with decent DIY/mechanical skills, but no specific knowledge of dismantling camera lenses?
I also have a Canon 50mm f/1.8 LTM (not Serenar) on which the focus ring has some "lash" in the action i.e. the focus ring turns a short distance before the lens starts to move. It causes no problem in practice, but it's rather annoying, and lets down the otherwise classy feel of the lens. Do you happen to have any information, or suggestions for correcting this, also?
TIA.
Is this a reasonably straightforward task for someone with decent DIY/mechanical skills, but no specific knowledge of dismantling camera lenses?
I also have a Canon 50mm f/1.8 LTM (not Serenar) on which the focus ring has some "lash" in the action i.e. the focus ring turns a short distance before the lens starts to move. It causes no problem in practice, but it's rather annoying, and lets down the otherwise classy feel of the lens. Do you happen to have any information, or suggestions for correcting this, also?
TIA.
johnamazement
Established
tbhv55
Well-known
Excellent - that looks very good.
Thanks for the link, and for the advice re- the screw-heads... I doubt that those screws are easy to buy on the high street!
Crazy Fedya
Well-known
I think, Yuri doesn't do any CLA's at the moment. His repairman has passed on about a year ago. On fedka.com there is no CLA listed anymore, either.
scorpius73
Well-known
I think I will contact Fedka first. If I don't get an answer I guess I will take to it myself. For a cheap lens it gives a quality to the images that I really like. Thanks for the help.
goamules
Well-known
I took my J-8 apart with no problem with the PDF reference above and some jewelers screwdrivers. You know they were made to be assembled easily, they also disassemble easily. I used some high temp grease for the helix threads and it is firm and smooth now. It's really simple to do.
Dez
Bodger Extraordinaire
Thanks! That was the site I was trying to find. This is a very good guide.
If the focus is loose, again it depends on which version it is. The one with the three screws at the back tends to be troublesome, as the friction both within the helical, and on the part moving against the removable back needs to be considered.
If it is loose, it may possibly be because some internal screws are loose (unlikely) or there is just too much play within the helical. This may be as a result of wear, in which case, the helical should be thoroughly cleaned so the metal filings in the lube don't cause more damage. It is also possible that the Quality Control guy just had too much vodka that day- FSU lenses are extremely variable as to build quality. The only real fix is to re-lube the helical (and the back part if applicable) with some high viscosity grease, maybe something for car wheel bearings. The focus will get really tight in the winter, but will be smooth and with little slop.
Good luck,
Dez
tbhv55
Well-known
*Bump* this question. Suggestions anyone?
johnamazement
Established
Does this happen when you start turning the focus ring from the extremes of its travel, or does the "lash" occur in between as well?
tbhv55
Well-known
It happens at all points in the travel of the focus ring, except when at the close focus extreme. Any advice would be very welcome - thanks.
[I've just realised that this particular question is somewhat OT (as it's an FSU thread) but this just kind of evolved from the original discussion. If there are objections, I'll start a new thread elsewhere.]
Livesteamer
Well-known
The gold standard for lens repair is a company in Colorado called Focal Point, run by John Van Stelton. It will cost a bit of money but he is very good. It might be simpler for a Jupiter 8 just to buy another but for a better/more expensive lens I would send it to Focal Point. Joe
roboflick
Well-known
cla is offered but he sends it to Ukraine, He charged me 110 dollars to service an Iskra, it came back in wonderful condition It took about 6 weeks
Nik
johnamazement
Established
As far as I remember from dismantling mine to clean it a couple of years ago, the front section of the lens—which moves whilst focusing—has a metal block or tooth (I'm sure there are proper terms for these but I don't know them) which fits between two brass stops in the rear lens mount section of the lens and connects it to the focussing helical. My guess would be that one of these parts has become loose or damaged and that accounts for the slop in your focus ring. The only way to be sure would be to dismantle the lens and have a look.
These lenses are very easy to work on (mine was the black-barrelled version but I assume they are all pretty similar). I managed to strip mine down to clear some internal fogging, lubricate the helical and clean and reassemble the aperture diaphragm and I'm certainly no expert. Owing to its simplicity, I wouldn't expect a professional CLA or service of the lens to be too expensive.
tbhv55
Well-known
That's great! Thanks for the information - very much appreciated.
By the sound of it, you stripped yours down without following any kind of instructions? If so, presumably everything is fairly obvious?
By the sound of it, you stripped yours down without following any kind of instructions? If so, presumably everything is fairly obvious?
johnamazement
Established
Yes, I worked it out as I went along: it's pretty straightforward. Start by removing the rear elements by undoing the rearmost retaining ring with a lens spanner (or sharp tweezers as I used). There may be another ring to remove underneath but if I remember correctly once these are out you can access the helical and should be able to see what the problem is.
Unfortunately I don't have the lens any more so I can't check for you, but do get back to me if you have any questions, I'd be happy to help if I can.
Cheers.
tbhv55
Well-known
That's really very helpful; very kind indeed.
As and when I get around to attempting the repair, I'll post on my success (or otherwise!).
As and when I get around to attempting the repair, I'll post on my success (or otherwise!).
johnamazement
Established
You're welcome. Good luck!