Mechanical XPAN, is it possible?

OlivierAOP said:
Here is my latest monstrosity. Wirgin stereo camera converted to panoramic with Mamiya 55mm lens. Blik rangefinder modded to couple with the lens. Seems to be accurate within 10cm at close distances. Rangefinders are really finicky; took a long time to make it work, IF it works. Will test with film next week. Also have a Bronica 40mm f/4 on a mechanical shutter I'd like to adapt.


DSCF7302 by Olivier, on Flickr
Click to expand...

Awesome work! Do you have notes that you could share on setting up the lens, mounting, calculations you made etc? I just acquired a Edixa Stereo for this purpose and the next step is to get a lens, and contemplate how to mount it. (Actually it's the 3rd Edixa Stereo I bought for this purpose, but the first 2 I started using for stereo photography and couldn't bring myself to dis-member them...)
 
I'm happy to share general guidelines, and to answer any specific questions.


1. locate the focal plane at infinity with respect to the lens
2. adapt the lens to an helicoid. The generic M42 ones are easiest but they are too fast: I recycled one from an SLR lens which has half the pitch. Rangefinder helicoids are even slower
3. determine offset from film plane to lens cone mount
4. subtract/add distances to determine cone height from cone mount to helicoid mount, then subtract at least 1mm for safety
5. via formula in my earlier post + helicoid pitch and diameter, you can make a focus scale
6. via this method (http://feuerbacher.net/photo/repair/InfinityFocus/InfinityFocus.html) you can locate the infinity point on your helicoid and stick the scale
 
35mm in the GSW690 worked great. With a 36 frame roll and no additional leader I got 14 shots on the roll, no issues with frame spacing. Unloading it in a changing bag was easy, just popped out the take up spool and the canister and rewound the film using one of the 120 adapters in the canister. Negatives are about 3.3:1 AR

50232914912_9c85a2a7c9_z.jpg


Shawn
 
Has a Sprocket Rocket been mentioned as a cheap alternative? It’s a long thread but I had a quick squint, don’t think it’s been mentioned.
Not only panoramic captures but double or multiple exposures too if you wish, or simply if you forget to wind on.
 
OlivierAOP said:
I'm happy to share general guidelines, and to answer any specific questions.

1. locate the focal plane at infinity with respect to the lens
2. adapt the lens to an helicoid. The generic M42 ones are easiest but they are too fast: I recycled one from an SLR lens which has half the pitch. Rangefinder helicoids are even slower
3. determine offset from film plane to lens cone mount
4. subtract/add distances to determine cone height from cone mount to helicoid mount, then subtract at least 1mm for safety
5. via formula in my earlier post + helicoid pitch and diameter, you can make a focus scale
6. via this method (http://feuerbacher.net/photo/repair/InfinityFocus/InfinityFocus.html) you can locate the infinity point on your helicoid and stick the scale
Click to expand...

Thanks very much for these steps. In terms of lens selection, what were the factors that you considered? So presumably it needs to be a lens with a shutter, and then also the image circle would need to cover the width of the panoramic opening in the film gate. Did you choose a lens first and then make/widen the film gate? Or vice versa? Out of interest what dimensions did you cut your film gate?

And with the focal length, does it make sense to choose a large format lens with a wide angle? Or does that come down to personal preference? Personally I'd like my images to look fairly normal i.e. without distortion in the corners. I'd appreciate any thoughts here.
 
I'm aiming for a 24x72mm frame; 3:1 AR feels plenty wide. 6x6 or 645 lenses work for that. To fill the Wirgin/Edixa 94mm gate you'd need a 6x9 lens (the Topcor series would be a good choice, or large format ofc). However lenses do cover more surface when stopped down, I'll soon confirm to what extend.

You can make a custom gate but without modding the film advance I don't think it's worthwhile.

Symmetrical-ish lenses (common in bellowed or rangefinder cameras) have less distortion. The wide-angle SLR lenses like my Bronica and Mamiya are retrofocus thus distortion is expected. Perspective distortion is however only a function of subject distance and FOV so at ~50mm and above you'll be good.
 
OlivierAOP said:
I'm aiming for a 24x72mm frame; 3:1 AR feels plenty wide. 6x6 or 645 lenses work for that. To fill the Wirgin/Edixa 94mm gate you'd need a 6x9 lens (the Topcor series would be a good choice, or large format ofc). However lenses do cover more surface when stopped down, I'll soon confirm to what extend.

You can make a custom gate but without modding the film advance I don't think it's worthwhile.

Symmetrical-ish lenses (common in bellowed or rangefinder cameras) have less distortion. The wide-angle SLR lenses like my Bronica and Mamiya are retrofocus thus distortion is expected. Perspective distortion is however only a function of subject distance and FOV so at ~50mm and above you'll be good.
Click to expand...

That's great information thanks!

I believe the Edixa Stereo is a 10 sprocket film transport (47.5mm), won't this mean that a modification to the film advance is required for panoramic format? I am also keen for a 24x72mm frame. I suppose that means I could still use the standard film transport in the Edixa Stereo but shoot every second shot in the dark, and put up with wide film spacing and some wastage of film. Otherwise, detach the double-exposure lock and just measure the number of winds (guesswork). Any thoughts?

For lens selection, I am almost considering adapting a Voigtlander Perkeo 6x6 lens (and bellows!?) to the camera, I wonder how that would go. If the lens can be positioned and held parallel to the film plane then it would have built-in focus (no need to work with helicoid adaptations) as well as a light-tight cone. I know a earlier comment recommended using the Perkeo itself for panoramic photos... could try that too one day.
 
Last edited:
You wouldn't need to fire a blank shot, just advance two stereo frames. The shutters on lens and camera are uncoupled. There will be some wastage without modding the advance.


I can't comment on adapting bellows. If using a 6x6 camera I would just crop 120 film and mask the viewfinder.
 
Developed a roll. Bad news: light leak. Good news: RF *seems* to work in the field and the Mamiya 55mm appears to cover the whole 92mm gate when stopped down.


SIM09549-1 by Olivier, on Flickr

I'm also developing myself for the 1st time in 20 years with untested equipment. I'll test a roll from a "proper" camera to see.
 
Added some foam around the door but still get a faint leak at the same spot. Strangely not on the first and last frames, which stood still the longest... RF works well so I'm happy. Pretty awkward camera though.


Obligatory mural:
SIM09680-1 by Olivier, on Flickr
 
OlivierAOP said:
Added some foam around the door but still get a faint leak at the same spot. Strangely not on the first and last frames, which stood still the longest... RF works well so I'm happy. Pretty awkward camera though.


Obligatory mural:
SIM09680-1 by Olivier, on Flickr
Click to expand...

That's awesome, great work on the camera. I haven't progressed mine yet - still working out how to dismantle the inners of the Edixa Stereo (I have removed all visible screws but the lens unit and inner chambers are all still sitting rock solid). Also too busy buying other gear... but I'll get back to the panoramic project soon.
 
Thanks!


After you've taken out the 6 screws at the front, you need to remove the lenses via the notched rings at the back. They're on tight!
 
OlivierAOP said:
Thanks!


After you've taken out the 6 screws at the front, you need to remove the lenses via the notched rings at the back. They're on tight!
Click to expand...

That worked! The lens unit is off now.

I was aiming to preserve the Stereo camera parts to re-assemble at a later date should the pano project go off the rails, but it appears that the internal metal construction needs to be cut away, is that correct? I.e. it's not possible to remove the stereo lens hole mount and build a replacement.

And would a Schneider-Kreuznach Angulon 90mm 6.8 lens be a suitable panoramic lens for this project? It looks to be relatively inexpensive and with a large image circle. Mounting may be a problem...
 
Yeah you have to open up the space between the lens holes, it's irreversible.

Any MF/LF lens in principle would work. The 90mm will likely have to stick out a fair bit from the film plane, and accurate focus will be tricky for close subjects because of narrow DOF. I'd try to use something under 65mm. I 3D-printed my lens mounts.
 
I'm also planning to build a Fauxpan. My body of choice is the Nimslo 3D for several reasons:
- once you remove the 4 lens "cones" the film gate is already 74mm wide
- the winder advances the film with one stroke and moves freely, so nothing to hack, it just works
- I like small cameras. This one is also light despite the metal chassis.
I already have the body, I bought a cheap one with a dead electronic shutter, but the mechanical winder works fine.
Now I'm waiting for a good lens opportunity. Ideally I'd like a Bronica 40mm because it would be very close to the field of view of an Xpan with the 45mm, and the aperture is relatively wide (f4).
 
Phildjii said:
I'm also planning to build a Fauxpan. My body of choice is the Nimslo 3D for several reasons:
- once you remove the 4 lens "cones" the film gate is already 74mm wide
- the winder advances the film with one stroke and moves freely, so nothing to hack, it just works
- I like small cameras. This one is also light despite the metal chassis.
I already have the body, I bought a cheap one with a dead electronic shutter, but the mechanical winder works fine.
Now I'm waiting for a good lens opportunity. Ideally I'd like a Bronica 40mm because it would be very close to the field of view of an Xpan with the 45mm, and the aperture is relatively wide (f4).
Click to expand...


Cool! Let us know how it works. It's funny because a Nimslo body is on the way. I have the Bronica 40mm and figured it would be a pain to swap it on the Wirgin because of the RF, plus the Wirgin is pretty big. Big thanks to A. Bieber on flickr for the inspiration. BTW I think the Bronica 50mm f2.8 would be a good match as well.
 
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