LTM Elmar 5cm f/2.8 set screw/grub screw problem

[StaaleS]

I bought myself a very pretty Leica III f with the collapsible 5cm Elmar 2.8 when I was vacationing in Prague. 1950's vintage stuff, in other words. The front of the lens assembly rotates freely, which I suspect is not supposed to be the case. It makes aperture change a two-hand job for one thing.

On closer inspection there is a threaded hole in the collapsible barrel section, 4-5mm in front of the focusing ring when the lens is fully extended, which mates nicely with a hole in the inner barrel, it seems that a set screw (or grub screw for the British-speaking among you) is supposed to be inserted there to key the inner and outer barrel together and lock the front in position but it is not there now.

Does anyone know the dimensions and thread of this screw, so that I can try to find - or make - a replacement? And, for that matter, is there supposed to be one there at all? With a sample of exactly one it is a bit hard for me to be absolutely certain of anything 🙂

Thanks in advance!

 

[Erik van Straten]

When the screw is not there it is quite a bad sign, for some incompetent repairperson could have been working on the lens. The best thing to do is to send the lens to a well-known Leica technician for a complete check up.

Erik.

 

[StaaleS]

The lens actually performs quite well, stopped down at least. As sharp as can be. At f/2.8 its performance isn't anything to write home about though.

 

[Erik van Straten]

The lens actually performs quite well, stopped down at least. As sharp as can be. At f/2.8 its performance isn't anything to write home about though.

I have the same lens, but it is very sharp at full aperture.

Erik.

 

[ZorkiKat]

Those little screws can fall off.

It's the size of a rice grain. You can perhaps try the screws used for eyeglasses. Or go to a camera repairist and ask them to put a screw there.


The loss of that screw should not cause your lens to lose its resolution. That 'grub' screw just keeps the optical block in place and prevent it from turning when the aperture is adjusted. The optical block, assuming that it has the necessary shimming, is pretty much fixed in the right place once the retainer at the other end of the barrel is tightened.

Tessar types at f/2,8 don't really do much. The same could be said of just about any other similar lens on other cameras when used at its maximum 2,8.

 

[Erik van Straten]

Tessar types at f/2,8 don't really do much. The same could be said of just about any other similar lens on other cameras when used at its maximum 2,8.

You should try the Leitz Elmar 50mm f/2.8 or the Leica Elmar-M 50mm f/2.8 at full aperture. They both are very sharp at f/2.8. The Leitz Elmar is however of lower contrast.

Erik.

 

[StaaleS]

OK guys, thanks for the input 🙂 Now I know that there is supposed to be a grub screw there, which makes perfect sense, and that it doesn't actually do all that much which also makes sense. I'll dig out the lathe and the tap&die set and see if I can make something out of brass that fits, unless my local optician happens to have suitable grubscrews lying around... camera repair shops are few and far between here in Norway. Being German I suspect the screw of being in metric, which is something at least. M2? M3? I'll have to trial&error that one. Or perhaps my FED-2 clunker can donate one for the greater good. I'll see.

From its performance stopped down I don't suspect the lens itself of having been tampered with to any extent. It really is quite absurdly sharp. At wide open it is about as good as I would expect a 1930's design to be which has had half a stop more squeezed out of it 🙂 Ie not very, but useable in a pinch if you are not too worried about the corner performance.

Is this thing coated by the way? It runs rings around my Summar-50 in the flare and contrast department, which does not say much perhaps, but I'd have expected to see some colour tint when looking at coated glass.

 

[Erik van Straten]

Is this thing coated by the way? It runs rings around my Summar-50 in the flare and contrast department, which does not say much perhaps, but I'd have expected to see some colour tint when looking at coated glass.

If you're talking about the Leitz Elmar 50mm f/2.8, then I can say that every single one of them was coated. You can see that by yourself by looking at the glass elements of your lens. If they shine some color, purple, blue, gold, orange or whatever, then your lens is coated. If they do not, the lens is not coated. Could be that for some reason the coating was removed.
Every Leitz lens that left the factory after the beginning of 1946 was coated. The Elmar 50mm f/2.8 was introduced in 1957. Maybe the lens you have is the Leitz Elmar 50mm f/3.5. Many of these were made before the war and are therefore not coated.

Erik.

 

[StaaleS]

No, it's certainly an Elmar 5cm f/2.8, it says so right around the front element after all 🙂 Can't se any trace of a colour sheen on the elements though. It may have rubbed off, it's been half a century since it was made after all. Judging by the serial number it is 1958 vintage.

 

[Erik van Straten]

Can't se any trace of a colour sheen on the elements though. It may have rubbed off, it's been half a century since it was made after all. Judging by the serial number it is 1958 vintage.

Could be removed because of problems. Explains also the missing grub screw. When I was you, I'd look for another example. It is a very fine lens, even at todays standards.

Erik.

 

[ZorkiKat]

You should try the Leitz Elmar 50mm f/2.8 or the Leica Elmar-M 50mm f/2.8 at full aperture. They both are very sharp at f/2.8. The Leitz Elmar is however of lower contrast.

Erik.

I have the Elmar 2,8 50mm, ca. 1963. Low contrast indeed. But I see no difference between what it does and what a typical 2,8 5cm Tessar-type does. I have Industars which give more 'snap'.

 

[Erik van Straten]

I have the Elmar 2,8 50mm, ca. 1963. Low contrast indeed. But I see no difference between what it does and what a typical 2,8 5cm Tessar-type does. I have Industars which give more 'snap'.

Maybe so, but that lens gives a very "even" sharpness over the whole field, also in the corners.

Did you try the Elmar-M 50mm f/2.8? It is a true Tessar with the diaphragm between the last elements. You'll be surprised.

Erik.