Jupiter 8 not aligning in mount??

[travellingcello]

Hi all,

Newbie here so please be gentle!

Got a Jupiter 8 LTM L39 mount lens in the post today, and fitted it to an also newly acquired ebay L39 to M adapter.

However when I screw the lens into the adapter and mount it on my camera, the lens doesn't line up correctly?

Pic below, as you can see the lens is off centre and is lined up to F5.6 on the DOF scale. It won't turn any further in the adapter.

Is this actually problematic and will it affect operation?

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IMG_0147 by TravellingCello, on Flickr[/IMG]

Also being relatively new to RF's could somebody advise me on how I can test focus accuracy or will I have to run some rolls through it to find out?

Thanks in advance!

TC

 

[Sejanus.Aelianus]

I have two rather more expensive lenses, a Takumar 50/1.8 (M42 SLR Mount) and a Voigtlander 15mm (Leica screw mount) which suffer the same problem. Both perform very nicely, so this may be nothing more than a cosmetic issue.

If you get some draftsman's tracing paper, open the back of the camera and tape a small piece of the paper, rough side out, across the film gate, you can check if the real focus and the rangefinder focus agree. Use a loupe or another camera lens to magnify the image on the paper, so you can focus critically.

Of course, the final test is always when you take some pictures, so you might want to do just that.

 

[ZorkiKat]

Not a real issue to be concerned with 🙂

On Leica and similar cameras, some Leitz/Canon lenses don't really line up at the "centre". Some were really made to have their index marks a bit to one side. Having the index there would make it easier to read the scales if something, like a pointy accessory viewfinder, was on the camera shoe.

With Soviet lenses, the entry and exit points of the helicals are not standardised. The index marks will almost always be off by a few degrees from the centre.

If the lens focuses right, and the main index line is just a bit off centre and can still be read from the top, then there's really nothing to be bothered about.

 

[travellingcello]

Thanks for your replies both, will try the tracing paper trick!

 

[Dwig]

Based on the trend of the number of similar posts I read on various forums it is far more likely that the fault is in theeBay sourced adapter and not the lens. The only way to confirm this would be to check the lens' mounting on a know accurate LTM mount (e.g. native LTM body, preferably Leica or Canon, or a high quality adapter, preferably Leica).

 

[jarski]

its normal feature of LTM-M adapter, nothing todo with lens. had it something todo with Visoflex (or finder as suggested above) and ability see lens controls better, dont recall exactly.

 

[ZorkiKat]

Thanks for your replies both, will try the tracing paper trick!

If you do the 'tracing paper' test, you ought to do it correctly, otherwise your observations will be inconclusive or inaccurate.

The tracing paper will serve as the focusing screen. It has to be absolutely flat (not easy to do with paper). It has to lie exactly on the film rails.

A better screen can be made with microscope cover/slide glass. Stick a strip of "magic tape" on one side. This becomes the ground side of the glass. Using glass will cancel the flatness issues. And being rigid, glass is also easy to place on the film rail.

If you can't keep the tracing paper flat or put it exactly where the focus plane is, what you will see will always be in error. Even a properly focusing lens will appear to be way off, even with a slight kink on the paper.

Why not shoot a few frames, full open, and focused on a carefully measured and marked target? On-film results are much more conclusive.

 

[ottluuk]

its normal feature of LTM-M adapter, nothing todo with lens. had it something todo with Visoflex (or finder as suggested above) and ability see lens controls better, dont recall exactly.

I thought the normal offset for the markings would be at about 1 o'clock (not 11 like the OP's lens) when viewed from the front so you could peer at the distance scale through the corner of the viewfinder. My 9cm Elmar sits like that (Voigtländer adapter) but my Jupiter-8 mounts perfectly straight (earlier silver version with focus tab, original Leitz adapter).

 

[ZorkiKat]

I thought the normal offset for the markings would be at about 1 o'clock (not 11 like the OP's lens) when viewed from the front so you could peer at the distance scale through the corner of the viewfinder. My 9cm Elmar sits like that (Voigtländer adapter) but my Jupiter-8 mounts perfectly straight (earlier silver version with focus tab, original Leitz adapter).

If you have several specimens Jupiter-8 (or any Soviet lens for that matter) you will notice that they won't mount in the same way on the same camera or in many other cameras for that matter. Even the tabbed collapsibles won't have their tabs park in the same place. Some at 7, others at 9 and still some as high as 11 o'clock.

That is the way they were built.