6x3 experiment on Bronica sq-a w/6x6 filmback

chung · Dec 7, 2020

This is my thought experiment on making 6x3 image on Bronica sq-a with 6x6 filmback.
Of course I'm thinking 50 or 40mm wide lenses.
I wonder anyone tried this or even this works.

It goes like this:
1. Take a first frame.
2. Then crank up to midpoint 1 and 2 on the frame counter, and flip the double exposure knob down, (so that film has advanced only 3cm or so ), and finish cranking ( cocking).
3. Take a second shot
4. Flip back the double exp knob back to normal position
5. Crank up from 1.5 (imaginary) to 2 on frame counter and repeat from #2.

Of course you cover the film insert beforehand so that only the center 6x3 will be exposed and use the viewfinder same way.
This way you can get 24 images of 6x3 instead of 12 on 6x6 filmback not wasting upper & lower film space od panoramic view. Koo
I'm not sure it will work, but it was my gedanken experiment this morning in my bed.

Koo Young Chung

BAC1967 · Dec 7, 2020

I have this splitter for a Polaroid Land camera that allows two shots per frame. If you can do double exposure with your Bronica this may be a much simpler solution. It wouldn’t be hard to modify a lens hood or a filter to mask half the image.

The Splitter by Bryan Chernick, on Flickr

This is a shot I did with it, it does give a soft edge between the images.

Cedar in the Sky by Bryan Chernick, on Flickr

Donald Qualls · Dec 7, 2020

The proposed method seems rather haphazard in terms of frame spacing -- especially because you'll need less and less crank angle for each half-frame advance as the film/backing build up on the takeup spool.

chung · Dec 7, 2020

Donald, I get your point, but doesn't the frame counter take care of it as long as you wind 1/2 frame as best as you can?

ic-racer · Dec 7, 2020

I'd look for a 6x4.5 film back if they made that for your camera.

glbeas · Dec 8, 2020

They indeed did make 645 backs for the SQa cameras. I may even have one stashed somewhere for mine.

Donald Qualls · Dec 8, 2020

chung said:
Donald, I get your point, but doesn't the frame counter take care of it as long as you wind 1/2 frame as best as you can?

Well, except for the "as best you can" part. Or does it? You might want to make up a dummy roll (cut backing paper to tape to backing paper to replace the film -- assuming your process your own you'll have all this in quantity) to test this so you can see the advance in the light. Take the back off and dark slide out, draw around the frame (on the dummy "film" surface) with a pencil, reinstall, do your "best you can" half frame advance, mark again, etc.

Likely a more repeatable method would be to cut a spare dark slide to cover a little over half a frame. Install one way, cock with the double exposure feature, install the other way, then advance film. You'll need a way to defeat the dark slide interlock...

grat · Dec 8, 2020

Donald Qualls said:
Likely a more repeatable method would be to cut a spare dark slide to cover a little over half a frame. Install one way, cock with the double exposure feature, install the other way, then advance film. You'll need a way to defeat the dark slide interlock...

The interlock is easy-- it's just a pin sticking off the side of the dark slide handle.

abruzzi · Dec 16, 2020

I think Donald's idea has the best chance of working reliably. You'll probably also want to mark the focusing screen, unless it already has a line across the middle. That should give you 24 frames at a 2:1 aspect ratio. Using a 6x4.5 back would be even easier, but will only get you 15 frames at an approximately 1.33:1 ratio.

Spot V · May 18, 2021

glbeas said:
They indeed did make 645 backs for the SQa cameras. I may even have one stashed somewhere for mine.

I recently saw a panoramic 135 film back for a Bronica, but don't remember for which model. The cool thing was that the film was placed in the horizontal orientation, rather than vertically, as is usually the case for 135mm film backs.

grat · May 18, 2021

Both the ETRS and the SQ, but they're ridiculously priced on eBay.

abruzzi · May 19, 2021

Spot V said:
I recently saw a panoramic 135 film back for a Bronica, but don't remember for which model. The cool thing was that the film was placed in the horizontal orientation, rather than vertically, as is usually the case for 135mm film backs.

they made that back both for the ETR series and the SQ series. They've gotten expensive, unfortunately, so I can't afford one.

edit: whoops, I said the exact same thing grat did..I should look before posting sometimes.

grat · May 19, 2021

Doing some research, however, I discovered that apparently you can modify the 135N (regular 35mm) back. The insert already has the roller position. There's a video on youtube, where he uses a file to open the film gate to the right width, but there's also a model on Thingiverse that's available. The person who uploaded the model does recommend having it printed in metal at one of the on-line print shops.

The downside is that the counter is still off-- you basically have to double-wind for each frame. It looks like the gear could be replaced with a different one to fix this, but I haven't found anyone who's done the work.

toyoboyo · May 19, 2021

I do something similar with a Hasselblad and 220 back. You can remove the advance gear from the easily enough. The later hasselblads have space for a 6x3 mask to fit between the film back and body.
Louis Zurn has some examples and explanations
https://www.louisrzurn.com/vpan-hasselblad-panorama

I get ~24-26 frames depending on how adventurous I want to be. It's ~.75 of a rotation for the first 17 frames, and then ~.5 rotation on the remaining frames using the advance knob of the film back.

ChristopherCoy · May 20, 2021

What about modifying a dark slide or two? A dark slide that is cut in half would expose the right side of the frame, and a second slide with a hole cut in it could expose the left side of the frame. Of course you'd have to figure out a way to override the lock system with the darkslide in.

6x3 experiment on Bronica sq-a w/6x6 filmback

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