Variable Focusing

[brians]

I find this weird. I have a Black Jupiter 8 lens (LTM) and a Industar 61L/D (LTM). I know that they're both different in focal length (50mm vs 55mm), but why do they "throw" off the rangefinder? When I focus at inf. with the Jupiter 8 on my FED5V, it's fine, but when I mount it onto a Zorki 6 (which focuses perfectly at inf. with a Industar 61L/D) it's off by a few meters!

Seems as if the Jupiter 8 has a longer focusing barrel (?). Any solutions to this?

 

[Sonnar Brian]

I have read in a few places, including the FSU sellers, that the buyer was to bring the new lens with the camera in for adjustment. If true, the lens was re-shimmed to work with a body.

That means you will have to adjust the two bodies to work with the same lens, then re-shim the 2nd lens to work with those bodies.

 

[Pherdinand]

heh? when focusing at infinity, it's off by a few meters?? that does not make sense, mathematically, to me... or did the infinity refer only to the industar?

 

[Jocko]

I had exactly the same trouble interchanging the Industar and Juppiter 8. I think its probably down to manufacturing tolerances - FED in its latter days was apparently not famed for quality control. Having inadvertently amassed a collection of 1990s 61L/Ds I've found significant variations between lenses. Being mechanically useless, I've taken the easy way out, with dedicated lens/camera combinations. It's irritating, but it saves continually adjusting the rangefinder.

 

[DaveP]

The best and wisest thing to do is set the flange distance on all the bodies to 28.8mm .Then adjust all the lenses to the same, now all lenses work with all bodies..........

 

[brians]

heh? when focusing at infinity, it's off by a few meters?? that does not make sense, mathematically, to me... or did the infinity refer only to the industar?

I didn't mean a couple of meters. It's a tad bit off though.

Brian, that would be the ideal solution, but I don't think it might be too practical.

Jocko, I've been getting used to using a Smena 8M and Kiev 35A, so my sense of guess-focusing has been getting better, but it would be a lot nicer to have a great functional lens. Thank you for understanding my pain.

"The best and wisest thing to do is set the flange distance on all the bodies to 28.8mm " <-- I don't understand, how would you go about this?

Thanks guys.

 

[DaveP]

Setting the flange distance.....well you need a good depth micrometer. Put the camera on bulb with a cable release to hold the shutter open. Set the micrometer on the flange and measure the distance from the flange to the pressure plate. The factory specs are 28.8 mm. You can raise and lower the flange using paper shims to get the correct distance.Be sure to measure at all 4 corners of the opening for the film in the shutter crate, not just take a measurement in the middle.Tighten the flange screws on a rotating basis a little at a time so the flange tightens down evenly. This is easier to do than it sounds but may be time consuming if you have to repeat the process several times to get the correct measurement.

 

[brians]

Wow, thanks Dave, I'll try that once I borrow a friend's micrometer!

 

[Nickfed]

I find this weird. I have a Black Jupiter 8 lens (LTM) and a Industar 61L/D (LTM). I know that they're both different in focal length (50mm vs 55mm), but why do they "throw" off the rangefinder? When I focus at inf. with the Jupiter 8 on my FED5V, it's fine, but when I mount it onto a Zorki 6 (which focuses perfectly at inf. with a Industar 61L/D) it's off by a few meters!

Seems as if the Jupiter 8 has a longer focusing barrel (?). Any solutions to this?

Having the J-8 off by a few metres is absurd. You may find the lens has been butchered or there is something astray with the RF follower. You don't say how the FED works with the I-61. If it is OK then it is time to suss the J-8, not the body - either of them.

The "50mm" and "55mm" are just names. Both lenses may actually be the same focal length, theoretically 52.3mm, and even if they are different, that isn't your problem. I submit you should do the maths before you do the dirty deed on whichever body. And then check the lenses, both of them.

 

[Pherdinand]

sorry brianS, maybe my comment was a bit wise-ass type, didn't mean that.
Getting used to a smena...hmm, the camera of my childhood. How do you find it, and why do you use it at all, is it considered like an experiment/toy/lomography experience or more serious?

cheers

 

[derevaun]

I'd check both lenses with an SLR first, to rule out a thread problem with the Zorki/J-8 combo that obstructs the lens before it's fully mounted. An incorrectly threaded helicoid would probably also cause what you describe, but it wouldn't focus at infinity correctly. Have you shot with both lenses wide open?

 

[brians]

sorry brianS, maybe my comment was a bit wise-ass type, didn't mean that.
Getting used to a smena...hmm, the camera of my childhood. How do you find it, and why do you use it at all, is it considered like an experiment/toy/lomography experience or more serious?

cheers

No problem 🙂 It was my mistake for reporting it wrong. I think the Smena 8M is just a neat camera. It is a pain to operate, but It's just so basic that it calls for me to do everything on my own. I suppose it is because I am still learning photographic basics. Just one year ago, everything would be done automatically with my digital point and shoot, but with the conversion to film, it's a bit different! It's more of a learning experience for me.

Nickfed, I clarified what you state in a later reply...

To further clarify this issue, the FED5V/I61LD at infinity shows a split image. I know it's focused at infinity (on the lens), but it does not show it on the rangefinder. It appears that a tiny turn counterclockwise (which cannot be done because it is at it's limit) would allow the FED5V's RF to be in focus. The I61LD on the Zorki 6 shows perfect focusing at infinity.

Next thing--the Z6/J8 combo has the opposite effect of the FED5V/I61LD combo. The Z6 focused at infinity shows that it is "past" infinity in the RF (split image to the left) which completely throws me off. From what it seems, it seems as if the FED5V is calibrated to match the J8, and the Z6 is calibrated to match the I61LD.

Derevaun, I haven't checked the lenses with an SLR as I do not have an SLR that will mount these lenses. It could be the threading, but I'm not sure. I think I might see how it works in my backup FED 4....

Thanks all.

 

[derevaun]

Sorry, the SLR trick is to use a SLR with a long lens as a collimator, as described here:
http://members.tripod.com/rick_oleson/index-123.html
http://www.kyphoto.com/classics/collimator.html
http://feuerbacher.net/photo/frame.html?repair/InfinityFocus/InfinityFocus.html~Main

Put a strong light behind the FED/Zorki. I use a strip of rigid plastic from a CD cover with very light scratches on it--it's important that the target in the film plane be very flat.

 

[brians]

Thank you derevaun for the sites.

DaveP, I finally understand what you are speaking of. I have compared two of my Jupiter 8's. The one in "trouble" is a black one (S/N 8201969), and the one that's properly working is the older chrome aluminum finish (S/N 6878237). It appears that it is the lens. The older J8 has screws missing so the screws that should retain the last ring with the depth of field markings is not in place.. I must find some. Anyway, this focuses "properly," similar to the other standard lens on my Z6, FED 2, FED 4, etc. I believe the true culprit is the black J8's and the FED 5V which is calibrated to "match" the faulty J8. Although I have not measured the difference with a micrometer, I think the black J8 is "taller" at infinity, like the tongue is a slight bit longer (by micrometers, I'm sure).

 

[DaveP]

Brians,
Good, you are getting some where with the problem. I had thought about that ring as Ive ran into the same problem. All these cameras should be calibrated to factory specs,that way any lens will work properly on any body plus the Leica and Voigtlander lenses use the same standard. Check ebay, you can get a good depth micrometer there for about 25-35 bucks. A cheap investment considering all the trouble is saves. I would reccomend a depth mike with the 2/12 to 3 inch base on it because it is handier to use. Get a metric if you can, just so you dont have to convert the reading from standard,but a standard will work fine.............good luck