50mm Type II DR Summicron circa 1950's

[pedaes]

Advertisement (gone after registration)

Well that's a question which has been answered.  The lens obviously unscrews from the focussing mount and also splits (unscrews) immediately in front of the aperture ring.  The serial number is also engraved inside there.  If you look at the 4th photo in Luigis' post #8, you can see exactly this.  <Edit> well you can't see the serial number but you can see where it splits.

 

Ok,good to know both parts of front cell are marked. As Luigi said, this part of lens is not meant to be 'customer' disassembled, and should need the special tools shown. I have not seen mine split.

[DaveM3]

Ok,good to know both parts of front cell are marked. As Luigi said, this part of lens is not meant to be 'customer' disassembled, and should need the special tools shown. I have not seen mine split.

I think the only special tool is the lens gripper, no need to remove any grub screws or anything like that as far as I am aware - mine wasn't originally so tight that it could not be unscrewed.  It was tight enough though and it would not come loose in normal use.  My original query was partly related to the fact that since it was serviced, I could not remove it - maybe it was tightened up just a little more than I am comfortable with and this would also explain why the black aperture dot is misaligned (further around from where it should be).

[pedaes]

I think the only special tool is the lens gripper, no need to remove any grub screws or anything like that as far as I am aware - mine wasn't originally so tight that it could not be unscrewed.  It was tight enough though and it would not come loose in normal use.  My original query was partly related to the fact that since it was serviced, I could not remove it - maybe it was tightened up just a little more than I am comfortable with and this would also explain why the black aperture dot is misaligned (further around from where it should be).

 

The lens gripper maybe only special tool, but Luigi points out three micro screws that need to be removed to disassemble optical cell. I think it could not be overtightened to the point where the apperture dot is significantly/visibly out of line. It is a very fine and smooth thread that comes to a obvious stop and would be extremely unlikely an experienced technician would overtighten. An earlier post asked who and you haven't yet shared.Something dosn't sound correct if you can simple split front section if Luigi is correct about screws. 

Edited September 25, 2018 by pedaes

[luigi bertolotti]

Well that's a question which has been answered.  The lens obviously unscrews from the focussing mount and also splits (unscrews) immediately in front of the aperture ring.  The serial number is also engraved inside there.  If you look at the 4th photo in Luigis' post #8, you can see exactly this.  <Edit> well you can't see the serial number but you can see where it splits.

Mmmhh… looking at my two items of similar age (DR 1.785.704, std. 1.986.334) and also at similar items I remember to have seen (here, probably), the hand-engraving inside the lens head is not exactly the s/n... more a "factory identifier" written during the assembly/checking phase : here's what is in my hands:

 

Summicron standard : serial number clearly and precisely engraved, and even painted, onto the focusing Mount : this is clearly an important match to be definitely recorded :

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

Summicron 50 DR : the same :

 

Summicron 50 standard - lenshead :

"34" and "19"... last two and first two digits of the s/n ? yes and no, imho : "19" indeed matches the small engraving on the focusing mount - the well known and visible  identifier for the real focal length (51,9); what about "N" ? an identifier of the technician ? Some factory check symbol ? Anyway, all is positioned where DaveM3 says

 

Summicron 50 DR - lenshead :

The ring (shim ?) where the previous engravings are, is CLEAN : engraving is on the inner barrel… "51,9" sounds a lot like the effective Focal Length (and all the DR, afaik, were 51,9.. the fact that my two items are both 51,9 is casual  ) , "4"... last digit of s/n ? (I doubt… maybe "glass set 4 has been mounted" ? Probably htere were different combinations certified for the Summicron)  "N"... see above ?

Edited September 25, 2018 by luigi bertolotti

[luigi bertolotti]

The lens gripper maybe only special tool, but Luigi points out three micro screws that need to be removed to disassemble optical cell. I think it could not be overtightened to the point where the apperture dot is significantly/visibly out of line. It is a very fine and smooth thread that comes to a obvious stop and would be extremely unlikely an experienced technician would overtighten. An earlier post asked who and you haven't yet shared.Something dosn't sound correct if you can simple split front section if Luigi is correct about screws. 

Sorry.. I wasn't rather clear : I said that the three little screws CAN be removed, but I doubt that this is a NEED to disassemble the front lens group .. that's why I say it's a job for skilled technicians…  I can speculate (but am not sure… probably there was some old fascinating manual for factory and dealers' repair people) that the dismounting sequence , depending on the kind of adjustment to be made could be : 

1) Cleaning/fixing of the two first elements of the front group: dismount only those, by front wrench (see photo - probably the two elements can be further separated with a spanner)

2) Cleaning/fixing of the two back elements of the front group : dismount front AND f/stop ring

3) Cleaning/fixing of the three elements (2 groups) at the back of the diaphragm : dismount only those - none of the previous operation  (it's the video I linked)

4) Fixing of the f/stop mechanism : dismount all the lenses' goups and the f/stop ring.

 

Our forum includes members that are really well skilled on repairs : their opinion is welcome and surely more trustable than the hipotesis from me, who am simply a perennial admirer and curios of those masterpieces of design - engineering - craftmanship.

Edited September 25, 2018 by luigi bertolotti

[DaveM3]

The lens gripper maybe only special tool, but Luigi points out three micro screws that need to be removed to disassemble optical cell. I think it could not be overtightened to the point where the apperture dot is significantly/visibly out of line. It is a very fine and smooth thread that comes to a obvious stop and would be extremely unlikely an experienced technician would overtighten. 

The front half of the lens optical assembly screws in and does not come to an obvious stop in the same way that the combined optical unit does not come to an obvious stop when screwing it into the focussing mount.  However, you know when the front assembly is screwed into the correct position when it tightens up and the black dot aligns exactly with the currently selected aperture marker.  By the way there is a thin spring washer between the front and rear halves which I guess is to prevent it from spontaneously unwinding.