Mechanical XPAN, is it possible?

The equivalent horizontal focal length would be 36/65*15=8mm. Too wide IMO!



I think most shift lenses are fine for 65mm frames. The gent at zeissikonveb.de has been using 24 and 35mm shift lenses on his cameras. The difficulty is in combining them with a shutter. I read on panomicron.com that the Nikkor PC lenses mount on a no. 3 shutter, but after looking at pictures of it disassembled I have my doubts.
 
And another one!

And another one!

Another conversion... maybe I have too many now 🙄



Zorki-6 with Bronica 50/2.8 on a Polaroid shutter (self-cocking). Inspired by user seg-k3. 24x60mm frame. RF coupling is done via the protrusion attached to the back of the lens; it simply contacts the cam follower. Went through a test roll and all seems to work. You can free the film advance by pushing and turning the shutter release. This allowed me to glue in a stop for the lever to adjust the frame spacing and get an extra frame or two.


DSCF7367 by Olivier, on Flickr


DSCF7368 by Olivier, on Flickr


DSCF7372 by Olivier, on Flickr


SIM00149-1 by Olivier, on Flickr
 
@OlivierAOP Quick question, just got a Wirgin Edixa Stereo to basically do the same conversion as you guys, but complications have ensued.


I've removed the 6 screws from the front plate, taken off the film mask and screwed the attatchment rings from the lenses. There's now a bit of play in the front assembly but something is still keeping it firmly attached. I suspect it has -something- to do with the rangefinder coupling (which doesn't exist in the simpler wirgin stereo you guys were disassembling). Bottom plate got me nowhere so I went in to take off the top plate.

Problem. The wind lever, and that cursed retaining nut. Trying to unscrew it anticlockwise (i.e. the normal way) isn't getting me anywhere, and trying to unscrew it CLOCKWISE is driving me up the wall. So quick question so at least I know I'm not tightening it instead of loosening it, is it reverse threaded do you know ?
 
I've been trying to remove that nut as well to check if I could mod the film advance. It very likely unscrews clockwise but It won't come off with my pin spanner!
 
OlivierAOP said:
I've been trying to remove that nut as well to check if I could mod the film advance. It very likely unscrews clockwise but It won't come off with my pin spanner!
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Damnit Oivier you were my only hope :-D

It's also impossible to find repair or service manuals anywhere for these things. General sentiment I've gathered seems to be that they weren't particularly well made, and weren't worth repairing when they inevitably broke.
 
OlivierAOP said:
I've been trying to remove that nut as well to check if I could mod the film advance. It very likely unscrews clockwise but It won't come off with my pin spanner!
Click to expand...


Ah. Progress, it's a normal screw, unscrews counterclockwise, but you have to lock the advance before you can get it off. Otherwise it just rotates endlessly. Don't have film in it so I had to rotate that little notched film wheel in the chamber until it locked.
 
Daire Quinlan said:
Ah. Progress, it's a normal screw, unscrews counterclockwise, but you have to lock the advance before you can get it off. Otherwise it just rotates endlessly. Don't have film in it so I had to rotate that little notched film wheel in the chamber until it locked.
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Well done! I was finally able to identify the rattle inside the cover.
 
OlivierAOP said:
Well done! I was finally able to identify the rattle inside the cover.
Click to expand...


Well, do tell ! When I popped the top off eventually a tiny ring popped out, about 1mm thick and maybe 3 or 4mm in diameter. No idea where it goes. The construction on this is pretty crude, it looks like it's one of those cameras where adjusting something means bending a bit of metal until it works.

Still haven't gotten the front off but getting closer. I want to try and keep the rangefinder mechanism on the top plate intact, and try a bodge job with whatever helicoid I stick on the front, so I don't want to go nuts on it yet.
 
Daire Quinlan said:
Well, do tell ! When I popped the top off eventually a tiny ring popped out, about 1mm thick and maybe 3 or 4mm in diameter. No idea where it goes. The construction on this is pretty crude, it looks like it's one of those cameras where adjusting something means bending a bit of metal until it works.

Still haven't gotten the front off but getting closer. I want to try and keep the rangefinder mechanism on the top plate intact, and try a bodge job with whatever helicoid I stick on the front, so I don't want to go nuts on it yet.
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My piece was very similar. A little spacer ring for one of the cold shoe screws. I tacked it back to the body.

I just went through a Soviet Zorki. The Wirgin is a fine watch in comparison!

Good luck with the disassembly. Keeping the RF might be tricky since it is built for a 35mm lens.
 
Ah, that's what mine is as well, one screw has a brass spacer, the other one has a gap between the top plate and the body, so it's likely that's where it's meant to sit.

RF wise I was thinking some kind of pushrod going through the top plate and pushing the RF arm, being actuated by some cam on the (rotating) helical. Eh, worth a try, if it doesn't work there's a shoe for an external RF anyhow 🙂
 
That's what I tried for the 40mm on the Zorki. 1) remove the straight cams from the helicoid so that the entire lens turned as it translated (watch out it'll fall off if turned too much); 2) made a sloped cam attached to the lens to mimic the movement of a 50mm lens.

Couldn't make it work... the turning cam shaded the image. But I gave up quickly knowing I had a 50mm handy. In principle it should work.
 
Further mods on the Wirgin. Mamiya 50mm f/6.3 6x9 with rangefinder unit hacked off a $15 Samoca LEII. RF patch is pretty dim but it seems reasonable accurate. The printed bayonet mount is not fully light proof. Wish I could find a SA 47mm... the Mamiya is truly massive.


DSCF7379 by Olivier, on Flickr
 
Let's say I want to obtain the same field of view as an Xpan with 45mm lens.
With a Super-Angulon 47mm (non XL) Would it be roughly the same?
I guess Xpan lenses have an image circle just wide enough to cover 24x65, so 72mm or so.
The SA 47mm has an image circle of 123mm, so I would use only about 60% of the width. Does it mean that with a SA 47mm I would get the equivalent of a 75 mm or so on an Xpan?
 
To get equivalent FOV focal length, divide the 35mm format size by your custom size and multiply by focal length.


Xpan horizontal FOV is 36mm/65mm*45mm = 25mm


So it depends on your film gate. If you want 25mm equivalent with 47mm SA you'll need a 68mm gate. But the SA will cover much more.
 
Yes I'm a dummy, I'm always tripped by image circle sizes, but a 47mm is always a 47mm, right? So with a identical film gate an Xpan 45mm or an SA 47mm will give similar images, whatever their respective image circles.
 
Phildjii said:
47mm is always a 47mm, right?
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For a given subject at a given distance from the camera, any 47mm lens should give the same image magnification. They may have different image circles though, because that depends on other factors in lens design (the angle of view, which often seems to be conflated with focal length).
 
joe bosak said:
They may have different image circles though, because that depends on other factors in lens design (the angle of view, which often seems to be conflated with focal length).
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Ahhh, at that point my brain melts. So would a SA 47mm and a 45mm Xpan give the same image with a 24x65 film gate?
The SA has a 123mm image circle with an angle of view of 105°, and I guess an Xpan "only" covers around 70mm and angle of view of 71°. I can't make anything useful of these informations… 😕
I think it should be similar, but don't feel confident in my math.
 
Yes, a 47mm lens would be very similar to a 45mm xpan with the same size film gate. The difference is with the 47mm you could go for a wider film gate since is has the possibility of covering more film.

When looking at different aspect ratios I tend to think of it in vertical coverage and then just which format captures more width. For example, shooting 35mm in my GSW690 I have the same vertical coverage as a 65mm lens on a 35mm camera (since it is a 65mm lens) but I get more than twice the horizontal coverage.

If you use a FOV calculator it is pretty easy to see how it all fits together.
https://www.pointsinfocus.com/tools/depth-of-field-and-equivalent-lens-calculator/

If shooting on 35mm film set sensor size for FX and whatever focal length lens you are using to get your vertical coverage. To see your horizontal coverage set the sensor size to whatever MF is almost the same width as you are using. Or you can use the Custom settitng and just put in heightxwidth of your film gate.

Shawn
 
Thank you Shawn, now it makes total sense. I was actually testings things on that lens calculator when I saw your reply 🙂
Now I understand what confused me: on lens specs both angle of view and image circle are given, but they are linked. If the SA 47 covered only 100mm, its angle of view would be 75°. I think in my head focal length and angle of view where somewhat the same, because I'm used to think in 35mm terms.
 
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