Bellows design question

[Randy_5116]

There are a lot of areas that cover bellows constructon, but none answers this question.... I recently acquired a Conley 8x10 New View BW Model with absolutely trashed bellows. Not even enough to use as starting point. I have noticed that the taper does not go straight from the 11x11 end to the lensboard, but rather tapers very slightly about halfway or so (?), and then tapers down to the lensboard. With 24 inch draw, (11 on extension rail, balance on mains) where in the hell do you start the major taper, and what would you make the large end of the lensboard end of the taper? I assume this difference in taper allows for full extension of the bellows when not using the extension without blocking shot. BUT would a person make it an 11 inch draw, 11x11 to lensboard, and then the balance straight? That seems like it would leave a lot bunched up to deal with. Long post, but I am ready to start bellows construction in order to reassemble camera.

[Paul Newson]

Hello Randy. Here are some thoughts . I've not actually made a bellows but I do have a home-made 6x9 mono-rail under my belt using a scrounged Crown Graphic bellows. I also have alot of formats on the old drawing board so I've given the matter some thought. I've seen variable tapers on other cameras before. An old 11x14 Deardorff and the new Arcas to mention two. I had allways thought it was a way of dealing with bellows sag and possible vignetting. The Arca bellows actually have opposing tapers swelling to their largest about a third of the way from the back towards the front. I suspect this takes care of the sag problem but also allows more compression for short lenses because the two ends nest into each other. Two birds with one stone. The Deardorff I mentioned had a straight bellows for about 12 inches from the back and then went into the taper towards the lensboard. About 2/5s straight and 3/5s tapered. Obviously they could not do as Arca does and still be able to close up the box. Score one for the monorail:) I suspect you know how taper allows for more compression when folded up and that gets back to your question. Without having any numbers to build to it seems you'll have to make up your own. But so what? I'd keep three things in mind; the extension you want to have, the compression you need to be able to close down to, and if you stick to the above ratio of taper to straight you'll probably be able to come up with something that works. If you use the rubber coated nylon sold as "darkroom cloth" by Porter's photo in Iowa you probably won't have a problem with compression. Just my 2 cents. Paul Newson

[Paul Fitzgerald]

Hi there,

Randy:"There are a lot of areas that cover bellows constructon, but none answers this question.... I recently acquired a Conley 8x10 New View BW Model with absolutely trashed bellows. "

Welcome to the wonderful world of 'pull your hair out'. If you have the original bellows left, your problem is solved, the design work has been done. If not, just make a straight, square, tapered bellows which is enough lay-out work for a weekend.

Making a 'double tapered' bellows would be a nightmare. In order to take-up the bunching you would have to work on the internal taper as well, using different sized pleats (vignetting) OR build 2 bellows and fuse them in the middle (messy, light leaks).

Have fun with it.