What's wrong with this Coll Cron?

[ampguy]

They are different

They are different

Let's look at form factor first for the 50s Crons -

1. Collapsible ltm, M - close focus is ~ 1m (prod ~ '53 to '63)

2. Rigid ltm, M - close focus ~ 1m (prod ~ '56 to '68)

3. DR M only, focus ~ 19 in. (prod. '56 to '68)

4. Coll. Elmar ltm and M ('59 to '68+)

1 and 2 are the same optics (per Hove 3rd ed.), while 3 and 4 may have benefitted from the computers mentioned that came on line while #1 and #2 were being produced.

Rigid and DR are one and the same per Lager (and MJS above). Except for the focal length of the DR being hand-selected. You can put a DR head into a rigid mount but not necessarily vice versa.

Ted, I repeat, IMO, the collapsible is a good lens. And you are right about haze on some used lenses ...

 

[Sonnar Brian]

I've taken a Type 1 Rigid apart, and three or so Collapsible Summicrons apart. The optics are not quite the same, and the mechanical fixture of the Rigid is JUST AMAZING. The optics are in extremely tight, and exactly placed. The air-gap spacing of the front elements and their thickness is different from the Collapsible Summicron.

On the pictures shown, I had the Type I Rigid Summicron professionally cleaned, and cleaned the collapsible Summicron myself. The Type I Rigid has higher resolution, but you really have to go to full-resolution scans to see it. We'll see what it does on the M8. Overall- I just like the collapsible better. Does not make any sense, I just do. The Type 1 Rigid and DR Summicron are the same, but the DR lens had tighter tolerance on the actual focal length.

And the Type 1 Rigid is computer generated! NO WONDER! I always told my optical engineer that I liked hand-computed lenses better. He told me the computer really did make his job easier.

And on the Collapsible Summicrons- there are at least two types: the original uses Thorium Glass, which was replaced early on. I have two Thorium Collapsible Summicrons and three of the later ones. The coatings were reformulated several times. I like the blue coatings in the 13x and later lenses the best. I also have the Type 1 Rigid and Type 2 Rigid.

 

[ampguy]

Hi Brian

Hi Brian

Let's forget about the DR for a second ok?

If your non DR rigid M mount Cron isn't equivalent optically to your M-mount collapsible cron (when extended ...), then you probably don't have it assembled right, and should send it somewhere for servicing. 😉

I've taken a Type 1 Rigid apart, and three or so Collapsible Summicrons apart. The optics are not quite the same, and the mechanical fixture of the Rigid is JUST AMAZING. The optics are in extremely tight, and exactly placed. The air-gap spacing of the front elements and their thickness is different from the Collapsible Summicron.

On the pictures shown, I had the Type I Rigid Summicron professionally cleaned, and cleaned the collapsible Summicron myself. The Type I Rigid has higher resolution, but you really have to go to full-resolution scans to see it. We'll see what it does on the M8. Overall- I just like the collapsible better. Does not make any sense, I just do. The Type 1 Rigid and DR Summicron are the same, but the DR lens had tighter tolerance on the actual focal length.

And the Type 1 Rigid is computer generated! NO WONDER! I always told my optical engineer that I liked hand-computed lenses better. He told me the computer really did make his job easier.

And on the Collapsible Summicrons- there are at least two types: the original uses Thorium Glass, which was replaced early on. I have two Thorium Collapsible Summicrons and three of the later ones. The coatings were reformulated several times. I like the blue coatings in the 13x and later lenses the best. I also have the Type 1 Rigid and Type 2 Rigid.

 

[ferider]

Let's look at form factor first for the 50s Crons -

1. Collapsible ltm, M - close focus is ~ 1m (prod ~ '53 to '63)

2. Rigid ltm, M - close focus ~ 1m (prod ~ '56 to '68)

3. DR M only, focus ~ 19 in. (prod. '56 to '68)

4. Coll. Elmar ltm and M ('59 to '68+)

1 and 2 are the same optics (per Hove 3rd ed.), while 3 and 4 may have benefitted from the computers mentioned that came on line while #1 and #2 were being produced.

With all due respect, Ted, I trust James Lager, my quoted references, and the fact that I have owned clean collapsible, rigid and DR more than the Hove pocket book.

Roland.

 

[ampguy]

I should get the Lager book

I should get the Lager book

Because every other reference indicates that the DR and Coll/Rigid (early) are not quite the same.

Below, is Lager saying that the DR is the same as the type 1 or type 2 (per DG's nomenclature) ?

I hope that you can see that they are physically different, e.g. the flat deck on the DRs and just round for the non DRs? Also, do the goggles fit a non DR Cron?

Also, I think we would agree that some changes are needed for focusing to 19" whether goggles, or cam/helicoil, right?

Rigid and DR are one and the same per Lager (and MJS above). Except for the focal length of the DR being hand-selected. You can put a DR head into a rigid mount but not necessarily vice versa.

Ted, I repeat, IMO, the collapsible is a good lens. And you are right about haze on some used lenses ...

I have a copy of Leica Viewfinder Vol. 39 / Nr. 1 / 2006 in PDF with more details on SOOIC-MS and SOSIC design. Email me if interested. In there (LEGENDARY LEICA LENSES, The 50mm f/2 “Rigid” Summicron by DICK GILCREAST), it says, among others:

 

[ferider]

Because every other reference indicates that the DR and Coll/Rigid (early) are not quite the same.

Below, is Lager saying that the DR is the same as the type 1 or type 2 (per DG's nomenclature) ?

I hope that you can see that they are physically different, e.g. the flat deck on the DRs and just round for the non DRs? Also, do the goggles fit a non DR Cron?

Also, I think we would agree that some changes are needed for focusing to 19" whether goggles, or cam/helicoil, right?

Of course the focus barrel is different between DR and rigid, Ted. But the optical module is interchangable (at least from DR to rigid).

For close focus and the DR you use the googles. The SOOMKY can be used with both collapsible, and with an adapter (forgot the name) with the head of rigid and DR.

Roland.

 

[ampguy]

Ok

Ok

So we agree that the Rigid Cron and DR are not the same, at least not all aspects like the barrel. Good.

Interchangeability does not mean similarity.

I think (but don't know) that the early collapsible, and early rigid are the same optically.

The DR, and post original Rigid crons may be different from the collapsible cron, but that's not relative to the OP's issue.

Of course the focus barrel is different between DR and rigid, Ted. But the optical module is interchangable (at least from DR to rigid).

For close focus and the DR you use the googles. The SOOMKY can be used with both collapsible, and with an adapter (forgot the name) with the head of rigid and DR.

Roland.

 

[ferider]

All I was saying is that based on my references that I quoted, rigid and DR are optically the same (except for focal length constraints on the DR), Mandler computer aided designs, and different from the collapsible.

I apologize to the OP for stealing the thread, and the somewhat boring exchange. 🙂

Take care, Ted.

Roland.

 

[bawang]

No apologies needed. This is good info here. And I do intend to get a Rigid one day (since DR can't be used on the D-M body).

 

[ampguy]

Thanks

Thanks

Thanks Roland for the great explanations and references, I am certainly enjoying learning about these potential differences, and the more sources the better.

Bawang - if it's not outside flare, or your filter, or condensation, I think you really need to consider there is some haze or coating issue and have that checked out. Good luck.

No apologies needed. This is good info here. And I do intend to get a Rigid one day (since DR can't be used on the D-M body).

 

[Sonnar Brian]

Ted- If I had paid someone else to CLA my Collapsible Summicrons, then I would still make the mistake to think it was the same optically as the Type 1 Rigid Summicron. It is not, again the glass elements are a different thickness and the air-gap is different. The type 1 Rigid that I took apart was an early one, SN 14x. And that Type 1 Rigid Summicron that I took all the glass out, cleaned, and reassembled tested just as good as this one that I kept. I sold the one that I did the CLA on to a friend for $200.

I like taking these old lenses apart just to see how they changed over the years. Cleaning them and getting them back together is just a bonus.

 

[ampguy]

Ok

Ok

Thanks for this info. I trust that you did see these differences between your early type 1 rigid, and collapsible cron.

I guess the definition of "optically identical" needs clarification. Many lens book authors and experts will look at group/element diagrams and without consideration for film to rear element distances or element thickness or air gap distance differences would still call lenses "optically identical"

But back to the rigid and collapsible cron, which I still think are optically "similar" I do have a question about why the IR mark was moved on the rigid to between f4 and f5.6 while on the collapsible around the f2 mark. [Merklinger, H. '94 Shutterbug article] DOF scales are the same. It is known that the rigid moves the glass out further from the film, is this the [only] reason??

Ted- If I had paid someone else to CLA my Collapsible Summicrons, then I would still make the mistake to think it was the same optically as the Type 1 Rigid Summicron. It is not, again the glass elements are a different thickness and the air-gap is different. The type 1 Rigid that I took apart was an early one, SN 14x. And that Type 1 Rigid Summicron that I took all the glass out, cleaned, and reassembled tested just as good as this one that I kept. I sold the one that I did the CLA on to a friend for $200.

I like taking these old lenses apart just to see how they changed over the years. Cleaning them and getting them back together is just a bonus.

 

[Sonnar Brian]

My optical engineer used the Term "Prescription" of a lens to describe its design. A Lens "formula" is more like a block diagram. When Bernie (my optical engineer) designed a lens, he modeled all of the optical surfaces, type of glass used, element spacing, coatings, etc. The type 1 Summicron and collapsible Summicron have the same block diagram but a "different Prescription" to use Bernie's term.

 

[Sonnar Brian]

Moderators: I think this thread needs to stay right here in the Optics forum!

Technical Discussion... Summicron exposed!

 

[Sonnar Brian]

IR Index: My Type 1 Summicron, Sn 15100xx, does not have an IR Index. I assume this means the correction is so good that it is unnecessary. It is at the F2 mark for the collapsible, and the Type 1 Rigid has even better correction.

The more the IR index moves from the center point, "pretty much" means the less corrected it is for chromatic aberration. My SN 120xxxx Summarit-M is just outside the F2 mark.

Were they talking about a later version Summicron with the move in IR index? I have not used the Leica lenses in IR YET, but will be with the M8. I have used a number of Nikkor lenses with an IR Digital camera for a long time. The 55/2.8 Micro-Nikkor is pretty good, as are ED lenses and Mirror-Lenses.