Let put the DR/Rigid arguement down

From : eppublic <eppublic@xs4all.nl>

Sent : Thursday, October 13, 2005 2:26 PM

To : Dan Chang

Subject : Re: Summicron DR and rigid rumor

 

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Hi Dan, I have read about this claim several times. It is not true.

But fighting against ingrained myths is a mission impossible. There

are very stubborn persons who want to declare the DR version as

sacrosanct. The original documentation about the DR at the Solms

archives does not mention anything special about the design or

assembly.

 

All the best

 

Erwin Puts

 

Dan Chang wrote:

 

I have heard someone claimed that due to DR's close focus

distance, Leitz has special QA or selection for DR's optical cells

and the tolerance is tight than rigid version. Can you comment on

this? thanks

Dan

 

 

See above e-mail

In most of the arguments about myth of leica, compare to these who

just use leica. 99% I am on Mr. Putz's side. at least he did MTF

curve to back up his claim and he has the ability to access the

leica techinque archive.

Dan, I love the DR, but that proves absolutely nothing :-)

 

Why don't all good Summicron lovers go back into their corners and take some pictures?

Sorry

I was chased by Mr. Flander.

I have the rigid version of this lens that I bought used in 1973. It takes fine pictures and that is all that matters. For close ups my 50mm 2.8 Elmar with the close focussing attachment is a better choice. The Summicron design was not optimized for close ups.

I am sorry you misinterpreted my comments. I wish to dispel the notion that I "chased you into a corner". I no way did I insist that any of the reports about the DR were established fact. The thrust of my comments was that it only seemed logical that in selecting lens cells for the DR, Leitz chose those cells most closely matching the focusing range of the mounts. Your inquiry to Mr Puts is garbled and does not in any way state the question. You seem to be hung up on the notion that I was claiming that the lens cells were corrected more accurately which was not my position in any way. In any event it doesn't make any real difference to owners or buyers of DR's except to assure that the actual focal length of the lens cell properly matches the mount. It is not uncommon to encounter specimens in which a cell from a rigid whose focal lenght is outside the accepted tolerance, in which case it would seem evident that the specimen is a Frankenstein. I harbor no resentments and would be happy to just let the matter drop.

The DR optical cell was selected for focal length. It was too complicated or expensive to make DR focusing mounts for all the different focal length groups. So they only used optical cells that were in the nominal (target) focal length group (51.9mm perhaps?).

 

For the normal rigid Summicron, they sorted the optical cells into 8 different focal length groups, and focusing mounts made to match each of those ranges. So there's a focusing mount for 51.3mm, another for 51.5mm, etc. This is why a rigid Summicron with non-matching serial numbers on the optical cell and focusing mount is a worthless mutt, you have little assurance that it will focus accurately.

 

The same matching of optical cells to focusing mounts also applies to all the earlier 50mm lenses, and to some other lenses.

 

For the 50mm lenses, they made different thread pitches on the helicals. For other lenses, they probably shaped the cam, on the rear on the wide angles, and internally on the telphotos.

I'd heard that same rumor 40+ years ago, that they selected 50mm Summicrons that were exactly 51.9mm focal length to make it easier to match up with the D.R. unit. Mu own version two 50 'cron has a very slight cam surface machined into the cam follower ring on the rear to compensate for individual differences in focal length lens to lens. This was very common, allowing them to use the same focussing mount with lenses of slightly different actual focal lengths. That was machining that could be done on the assembled finished lens.

Thank you, Mr Shriver. You state the issue much better than I could. However, I am still ready to let the matter rest and would hope the Mr Chang will concur.

I have a 1957 Summicron 50mm lens head together with two mounts: a rigid (SOSIC) and a

DR (SOMNI) with its removable spectacle.

 

The 3 items (lens head and both mounts) are all (factory) engraved with the same serial

number (14733XX).

 

Both mounts have a 8 engraved on the back which match the 51,9 (true focal length)

scratched on the rear mount of the lens head.

 

Lucien

John Shriver stated it perfectly.

 

I can not separate the pictures from my DR and Rigid. They are the same.

Well, I've owned two DR Summicrons, both 51.9mm. So there.

I have a beautiful DR Summicron with eyes & case for eyes that I will probably put on the auction site tomorrow. Email me at pdn42@optonline.net if you're interested.