35mm Camera/Register ~ 36mm/Behind The Lens Leaf Shutter — Shortest Possible Length?

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radi(c)al_cam

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Dear friends,

recently I’ve mentioned that I was planning to do something with my Geiss modified Argus C-4, cf. http://www.rangefinderforum.com/forums/showthread.php?t=158062

I figured out that my project should work even if I don’t have a spare bayonet; I just have to let an expert cut a thread into the opening in front of the shutter, and with some luck I can use a couple of the Novoflex «rings» made in the 1960s/70s/80s (I suppose) that I have.

(Short explanation regardings these Novoflex joining rings: contrary to common belief, these LeiMin, LeiCont, LeiPent etc. were never intended to be used as adapters for Leica cameras, but actually for the Novoflex bellows that had a M39-mount).

And finally, I have a rangefinder camera that tells me what distance I have to choose when I adapt an SLR lens 😀

Now my question: What is the shortest SLR-lens that I can use without having darkened corners?
 
I'm not really sure what you want to do, or why you're doing it, whatever it is. If you are planning on putting a SLR lens on your Argus w/ adapters, you will need to know the exact film to lens plane distance, and every camera manufacturer has a different one. A SLR lens isn't going to darken the corners, it will just be very difficult to set the correct infinity focus distance using a RF camera, and even if you get that right you will still have to scale focus it.

You are basically trying to reinvent the wheel. I am a big fan of using different lenses on cameras w/ adapters, but that is on SLR cameras where you can see if things are focused perfectly or not in the viewfinder, not on RF cameras, where it is going to be considerably more difficult to do that.

You would be a LOT better off spending $20 for an old Nikon or Canon SLR w/ a nice lens already on it.
 
If the project has an element of sport rather than a practical purpose , and if the back of the camera can be opened: use a ground glass + magnifier on the film rails to set the lens to the distance you wish to use at its largest aperture. Voila- a single-distance hyperfocal focus Argus without fiddling with rangefinder cams.

p.
 
This sounds like a fun project. Finding compatible lenses, particularily wide angles, will be a bit of a Trial-and-Terror experience.

There are issues beyond the mere mounting flange specs, of which at least the "register" distance (film to flange distance) is easy to find on the web. All SLR mounts require that some lens components (lens flange, diaphragm linkage, rear elements, rear element shields, ...) protrude into the body rearward from the face of the body flange. Finding the spec for the maximum distance allowed for any of these protrusions is all but impossible.

A quick check on my 55mm f/1.8 Auto-Takumar (I don't currently own any wideangles for SLRs) shows that it protrudes nearly 7mm from the face of the flange. Given that the register distance is 44.46mm, this means that when focused to infinity (the rear most protrusion is its rear element) it leaves ~38.5mm clearance between the film and and rear of the lens. While this would clear a C4's shutter at 36mm, some Takumar wide angles may protrude deeper into the body and conflict with the shutter.
 
Steve M. said:
I'm not really sure what you want to do, or why you're doing it, whatever it is. If you are planning on putting a SLR lens on your Argus w/ adapters, you will need to know the exact film to lens plane distance, and every camera manufacturer has a different one. A SLR lens isn't going to darken the corners, it will just be very difficult to set the correct infinity focus distance using a RF camera, and even if you get that right you will still have to scale focus it.

You are basically trying to reinvent the wheel. I am a big fan of using different lenses on cameras w/ adapters, but that is on SLR cameras where you can see if things are focused perfectly or not in the viewfinder, not on RF cameras, where it is going to be considerably more difficult to do that.

You would be a LOT better off spending $20 for an old Nikon or Canon SLR w/ a nice lens already on it.
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Thank you for your answer, Steve 🙂

No, I'm not planning or «basically trying to reinvent the wheel» 😀

And I'm aware that it's just a slightly improved scale focusing and not a true auto-focus in the historical sense since I'll have to transmit the distance reading manually 😉

cf. my thread re: 🙁 What Happened to the «Rangefinder Coupled SLR to Leica M Adapters»?

And, of course, there are already some SLRs in my possession — but …

ph. said:
If the project has an element of sport rather than a practical purpose , and if the back of the camera can be opened: use a ground glass + magnifier on the film rails to set the lens to the distance you wish to use at its largest aperture. Voila- a single-distance hyperfocal focus Argus without fiddling with rangefinder cams.

p.
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Exactly, dear p.!

Yes, the back is removable, and I have a ground glass, I just have to find my jeweler's loupe somewhere in my basement vaults…

And I also agree with Dwig:

Dwig said:
This sounds like a fun project. Finding compatible lenses, particularily wide angles, will be a bit of a Trial-and-Terror experience.

There are issues beyond the mere mounting flange specs, of which at least the "register" distance (film to flange distance) is easy to find on the web. All SLR mounts require that some lens components (lens flange, diaphragm linkage, rear elements, rear element shields, ...) protrude into the body rearward from the face of the body flange. Finding the spec for the maximum distance allowed for any of these protrusions is all but impossible.

A quick check on my 55mm f/1.8 Auto-Takumar (I don't currently own any wideangles for SLRs) shows that it protrudes nearly 7mm from the face of the flange. Given that the register distance is 44.46mm, this means that when focused to infinity (the rear most protrusion is its rear element) it leaves ~38.5mm clearance between the film and and rear of the lens. While this would clear a C4's shutter at 36mm, some Takumar wide angles may protrude deeper into the body and conflict with the shutter.
Click to expand...

Thank you for the heads up, I'll make sure that I won't damage the shutter after it so far survived so many decades, and even my very wild brats that usually take everything apart, particularly my old cameras 🙂
 
Corrigendum: Flange Register

Corrigendum: Flange Register

Eventually, this night I found my vernier/calliper, and surprise surprise: the actual flange register is only ~32mm — that makes things a lot easier!

(But nevertheless, due to the narrow throat in front of the shutter, I won't be able to use Contax-RF lenses 🙁)
 
radi(c)al_cam said:
One thing: Your list, and others that I've seen too, have «Argus bayonet 44.45 [mm]» — is that a completely different Argus model, or: perhaps the rim of the external part of the bayonet could be meant? 😕
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Not sure, actually! I put the list up from a list that used to be online but nowadays is down.

I'll get online tomorrow (past bedtime here now) and see what I can dig up on the matter. I'll report back in this thread and update the list on my site with what I find.
 
johannielscom said:
Not sure, actually! I put the list up from a list that used to be online but nowadays is down.

I'll get online tomorrow (past bedtime here now) and see what I can dig up on the matter. I'll report back in this thread and update the list on my site with what I find.
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The British film guys have some additional informations: http://www.filmcentre.co.uk/faq_lens_m.htm

note 15: Argus, screw thread or C44 bayonet which had a unique focus ring on camera engaging with lens barrel to rotate heliciod.. Most lenses were Steinhill, while the standard on the Argus C-44 camera, the kitch looking 50mm f:2.8 Cintagon (a tessar), made in Michigan c1956, is said to be one of the first commercial lenses wholly designed on a computer, the University of Michigan developed MIDAC. .
Click to expand...
 
There are certain people who would pay good money for a C-4 Geiss Modified, Alexander. Maybe you'd want to do this modification with the more common C-44, just in case you bungle the first try.

PF
 
radi(c)al_cam said:
One thing: Your list, and others that I've seen too, have «Argus bayonet 44.45 [mm]» — is that a completely different Argus model, or: perhaps the rim of the external part of the bayonet could be meant? 😕
Click to expand...

An "Argus Bayonet" mount would be for the C-44, which was a variant of the C-4 that has interchangeable lenses.

The Argus C ("C-1"), C-2, and C-3 models had interchangeable lenses, but used a thread mount, not bayonet.

Hiere's a table of mounts sorted by register:
http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html
 
farlymac said:
There are certain people who would pay good money for a C-4 Geiss Modified, Alexander. Maybe you'd want to do this modification with the more common C-44, just in case you bungle the first try.

PF
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Thank you for your concern, dear PF, but I'm afraid, I can't do that, for two reasons:

a) In Europe, particularly Continental Europe, all the Arguses are very very uncommon — noone had them then (unless you've been allowed to buy your stuff at a PX store, one can suppose).

(Hence I'm inclined to presume my specimen that I purchased from Western Germany some 10 years ago might have been a GI's gift for his «Fräulein», or so …)

b) My C-4 has that very useful — to me: crucial — distance readout on the wheel, but: the C-44 doesn't, unfortunatley.
 
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