Fuji GW690iii 6x8 or 6x7 conversion

OlivierAOP

OlivierAOP

medium format
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I recently got a GW690iii. Great camera but 6x9 is a lot of negative and 8 frames is not a lot. Since it is very similar to its 670 and 680 siblings I thought one could do a conversion.

Under the frame counter wheel there is an assembly. It has a fine toothed gear that turns in proportion to the film roller, and a notched disc that indexes the film advance. I reverse-engineered the pattern of that disc, putting 18 or 20 notches instead of the 16. 3D-printed a disc and completed the assembly. I added a frame mask in a convenient recess in the film gate.

replacement part vs. original by Olivier, on Flickr

On the body by Olivier, on Flickr

I tested it with backing paper and it looks like it may work. The assembly needs a bit of work yet. This is for 6x8 but 6x7 should also be possible.
 
Judge Holden said:
Absolute mad lad
Click to expand...

That's funny. For me the inside of those cameras is a bit like a Rube Goldberg machine. I figured out a small part of it. At any rate it works! But spacing isn't perfect and the roll starts a bit early. I'll offset the start line next time.

To my untrained eyes there is very little difference in the composition between 6x8 and 6x9. GW690, now with 12.5% more frames!

20211127_171855 by Olivier, on Flickr
 
That’s cool. The real Fuji 6x8’s were Japan-only I think - so somewhat rare for what I think is the optimum format.

When you’re done you can 3D print a custom label to put over the 6x9 on the front.
 
Thanks! Yes the 680s are a bit less common AFAIK. I think I prefer the 6x7 ratio (4:5) but 6x8 (4:3) is pretty nice. The latter is only a bit wider (5-6mm) but it adds up to one less frame.

It's funny this camera has a replacement GSW top cover. I should bastardize it further with a custom label.

I think I'll reduce the frame size via the mask by a mm or so and give the 6x7 mod a second chance.
 
Once you go to medium format, talk of economizing on film seems somewhat pointless, although wanting a different aspect ratio does make sense. Nevertheless, I do understand the urge to tinker, having fallen victim to it on many occasions, and I confess to having destroyed an Iskra in the attempt to convert it to 6x4.5. Good luck with your project, and may your Fuji survive!
 
I think the 6x7's were designed to mimic the reproduction ratios of the most common papers of the day (8x10, 11x14, 16x20) so you could print full frame without cropping. The 6x9's were designed to bring medium format resolution to the same aspect ratio as 35mm film. Nice work on that 3-D printing! I think it is the future of keeping these beasts running. Impressive mod!
 
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