DIY Cambo Wide Help

[wjlapier]

I'm considering making a Cambo Wide type camera and have some questions.

Using a focusing helicoid how fare should the lens be from the film plane to obtain infinity focus? I see there is a helicoid on Ebay and it travels 9mm. If you racked the helicoid out how far from inifinity would you be--what would be the minimum focus for 9mm of travel? Is there a way to calculate this? I'm considering using a Fujinon 90mm f/8 lens. I've never shot a large format camera so this is all new to me, but so far I do have most of the parts. Just the front lens board and focus helicoid is all that I need--and any spacers if I need them. I'd hope to do most fo the machining myself, but might send some parts to SK Grimes if need be.

 

[Dan Fromm]

Oh, my, what an old question.

The published flange-to-film distance for the 90/8 Fujinon varies from 98.2 mm to 98.4 mm. Actual flange-to-film distance is probably different. The only way to find out what it is is measuring.

If a 90 mm lens is focused at infinity, moving it 9 mm forwards from the infinity position will give magnification = 1:10. Front node-to-subject distance (approximately diaphragm-to-subject distance) will then be 11 focal lengths = 990 mm. Film plane-to-subject distance will be approximately 12.1 focal lengths = 1089 mm.

 

[xya]

you should specify the lens ou want to use. I got a 47mm cambo wide, but there are other focal lengths as well...

 

[Nokton48]

You could clamp the lensboard, and and clamp and focus the groundglass at infinity, throw a darkcloth over the whole thing. Then measure carefully, and see what you have to build out in terms of a box. There are also generic helicals on Ebay from China. Those should work on your 90mm F8 Fujinon. Don't know about build quality. Schneiders are Primo.

Building my homemade Norma Handy took six months. Take your time and test everything.

 

[Nokton48]

Here are some 90mm fixed focus box cameras, to which you could add a helical.

90mm Box Cameras by Nokton48, on Flickr