50mm Type II DR Summicron circa 1950's

[DaveM3]

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I have had my beloved lens repaired recently but the repairer hasn't responded to a question about the lens since I got it back so posting here in the hope that there is someone knowledgeable enough to know.

 

I've had and used the lens for a few years and discovered that the front section actually unscrews just in front of the aperture ring (which exposes the aperture blades internally).  I realised this because the aperture ring markers didn't line up exactly with the dot and I read somewhere that it can simply be unscrewed and re-tightened to the "correct" position such that the dot aligns perfectly.  So I did.  Great so far.

 

Earlier this year, the lens developed a fault in the focus mechanism; it became notchy/rough and would over-extend the infinity position.  So I sent it off for repair.

 

When I got it back, the first thing I did was to try to re-adjust the front section to re-align the aperture dot since it was now out of alignment again.  But I could not unscrew it and don't want to apply excessive force to do so.  Then, the whole lens assembly including front and rear sections of the lens began to unscrew from the focusing mount and I could actually take it out and put it back in again.  So my first though was that perhaps this is how it is supposed to be i.e. it can be removed (I read somewhere else that there was a device in which you could place the lens body for some purpose, can't remember what).

 

So my questions are:

 

1) Is this normal i.e. should I be able to unscrew the lens body including all the glass from the mount?

2) If so, how do I tighten it back in - I mean how tight and would it affect the calibration of the lens in some way?

 

Thanks

 

 

 

 

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[pedaes]

Yes, the optical cell unscrews from the focusing mount. The was to enable the lens front to be mounted in a Visoflex adapter. I just screw mine in until it comes to a stop and then give a little 'tweak' to tighten it. As they were designed to unscrew by hand with no tools I can't think you need more than a snug tightening.

Edited September 24, 2018 by pedaes

[satijntje]

I think it is also the case for the rigid Summicron from the fifties

[TomB_tx]

Yes, the lens heads for the rigid and dual-range are identical.

[UliWer]

....  Then, the whole lens assembly including front and rear sections of the lens began to unscrew from the focusing mount and I could actually take it out and put it back in again.  So my first though was that perhaps this is how it is supposed to be i.e. it can be removed (I read somewhere else that there was a device in which you could place the lens body for some purpose, can't remember what).

 

So my questions are:

 

1) Is this normal i.e. should I be able to unscrew the lens body including all the glass from the mount?

2) If so, how do I tighten it back in - I mean how tight and would it affect the calibration of the lens in some way?

 

Thanks

Yes, it should be as you describe it. The „rigid“ Summicron‘s lens head - without the focussing mount - could be used together with the SOMKY attachment for close ups. Though of course this was not important for the dual range Summicron which had its own close up goggles and mechanics.

 

You just screw in the lens head, so that it is tightly fixed without using much force. Calibration should be no problem.

 

Though the index for f-stops at the lenses front should always be in the 12-o-clock-position. If it isn‘t something was not properly fixed.

[DaveM3]

Ah OK thanks everyone for your help.  That's very good to know, I was concerned about calibration.  Regarding the aperture dot, it is at 12 o-clock but just a tiny amount out from the selected aperture mark, which I suspect isn't a big problem.  

[gyoung]

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What surely isn't right is that it unscrews in front of the aperture ring, exposing the aperture blades.

On my lens (actually not a DR, but this is the same) the whole optical cell (all elements with diaphragm within) unscrews from within the focussing mount.

 

Gerry

[luigi bertolotti]

As above said, it is NORMAL that the lens unit of the Summicron DR (and non-DR too) is easily unscrewable from the focus unit : a standard feature, designed as a "partial disassembly" Customer-made for mounting on accessory systems. This does not mean that the lens unit in itself is impossible to further be unassembled : but this is for maintenance by labs, not designed to be customer made… it needs skill and special tools to expose the aperture blades, which are in the middle of the lens goup : four elements in front of (un-cemented... "air elements"), three behind (a couple is cemented), so, as Gerry says,isn't normal that the front goup unscrews easily exposing the blades : it must not.

 

The "Customer disassembly" of the DR brings to such devices :

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Then, these 3 little screws at 120° each, that secure the aperture ring can be removed… and they are very little… this is already a not amateurish task (not a DR, but head is the same, mechanically) : 

 

Then, with proper wrench, one can disassemble the first group of 4 lenses…

 

… and the back one too…

 

here's a video about the cleaning of the 3 back elements (unrelated to your issue) :  https://www.youtube.com/watch?v=v5vyLYe863k

 

Summicron DR is such a beautiful piece of engineering (and still an excellent lens to use) that is a pity not to have it in good shape… and is a lens finely designed with maintenance in mind :

in Europe and USA there are smart labs that are well up to the task of making a very good restoration of it… glass elemnts included if needed : it worths the cost, in my opinion.

Edited September 24, 2018 by luigi bertolotti

[TomB_tx]

What surely isn't right is that it unscrews in front of the aperture ring, exposing the aperture blades.

On my lens (actually not a DR, but this is the same) the whole optical cell (all elements with diaphragm within) unscrews from within the focussing mount.

Gerry

This is because the optical cell was seated too firmly in the focusing mount, so that when you try to remove it the fron group comes loose first. I have a DR with the same condition, and haven’t found a way to correct it. I had a good tech do a CLA, who said it was best to leave it that way or risk damage.

[DaveM3]

Hi Gerry, it does though I can testify to that.  The aperture blades are between the front and rear groups of glass.  I'm not sure why it is so easily done (although as I described it is stuck pretty fast since it came back from service) i.e. what would be the purpose other than perhaps for servicing?

[DaveM3]

This is how the aperture index lines up with the dot:

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[jdlaing]

Who repaired it?

[pedaes]

This is how the aperture index lines up with the dot:

IMG_2230.JPG

 

That 'dot' looks like the small locating ball in the centre of the 'flat' at the top of the lens when mounted and the position is correct. The aperture dot and the focus mark do not align exactly on my copy.

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Edited September 25, 2018 by pedaes

[pedaes]

UliWer's comment got me interested in this. Turning to the literature, Laney shows a lens as UliWer describes, but Puts (pg461 of Compendium) shows the index points misaligned as copy above. Laney shows a standard 'rigid' (pg 235) with the aperture mark aligned with the red mounting dot. So - looks like there is some variance lens to lens. Be interesting to hear comments.

[a.noctilux]

I have some ideas for the dots that are not align each other.

 

I think that can be cured (aligned) with adjustments by people who know how to do that.

 

I own three DR and when I swap ( for experimentation ) the optical heads, those dot don't align anymore.

 

So to be certain that the lens mount body and the optical head are matched, Leitz doubled the lens head number inside the mount.

 

Mine when "matched" align perfectly :

 

 

As I understand, each optical head (even they are "all 51.9mm focal length") is matched to the mount with same number.

Not swappable each other !

Edited September 25, 2018 by a.noctilux

[DaveM3]

I checked and the serial numbers do match.  I remember also that a matching serial number is engraved behind the front optical assembly i.e. on the mating surface of the section containing the aperture blades and rear optics.

[pedaes]

Not sure about where you mean for numbers. Optical cell is lens number in usual place on front ring, and then on front face of focusing (rear part) of lens. Very neat engraving on face that optical cell screws into. This part of lens does not contain any elements or aperture blades. Perhaps we are back to issue of where your lens splits.

 

I checked and the serial numbers do match.  I remember also that a matching serial number is engraved behind the front optical assembly i.e. on the mating surface of the section containing the aperture blades and rear optics.

Edited September 25, 2018 by pedaes

[luigi bertolotti]

Not sure about where you mean for numbers. Optical cell is lens number in usual place on front ring, and then on front face of focusing (rear part) of lens. Very neat engraving on face that optical cell screws into. This part of lens does not contain any elements or aperture blades. Perhaps we are back to issue of where your lens splits.

Yes… there is no relation between  lensheads matching and f/stops dot alignement. : all the mech of the diaphragm is inside the lenshead itself : remove the lenshead, mount it  onto another focusing unit…  and nothing changes about f/stops  (while, the focusing can be no more correct : indeed, as above said, lenshead is matched to its focus unit, both numbered accordingly)

Edited September 25, 2018 by luigi bertolotti

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[sblutter]

I was told long ago that the cell & mount were calibrated together - thus matching numbers

[DaveM3]

Not sure about where you mean for numbers. Optical cell is lens number in usual place on front ring, and then on front face of focusing (rear part) of lens. Very neat engraving on face that optical cell screws into. This part of lens does not contain any elements or aperture blades. Perhaps we are back to issue of where your lens splits.

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.