Bag bellows: how big is too big?

[Foto Ludens]

Just out of curiosity (think "homebrew bellows"): How big can bag bellows go before they become impractical?

I'm thinking of 5x7 type stuff, and making a bag bellows for a normal lens.

Anywho, what's your take on this?

 

[glbeas]

Well, if you think of a normal bellows as having many small pleats and a bag bellows one big pleat, how far can you go before it gets in the way? Then consider whether it will fall between the lens and film when extended. All variables with material, scale and extension. My Calumet bag is of fairly stiff material so it doesn't sag when pulled out, but has a fairly short run. Why do you want one for a normal lens? Going to use extreme movements?

 

[Foto Ludens]

Thanks for the reply, Gary.

I don't own a LF camera yet, and every once in a while I think about putting one together. A bag bellows just seems easier to make than a pleated one, and extreme movements are the major appeal of LF to me. A DIY approach would let me work within my budget, even if it costs a tad more by the time its done.

So I'm dreaming of a 5x7 monorail with unlimited movements (well, you know what I mean). 4x5 is too small to contact print, 8x10 is too costly lens and holder wise (and film).

I'm thinking about making bag bellows out of a fake leather material. I wonder if it would be strong enought to make a bellows which could go to 16 inches with room for movement. It would have to be a BIG bag, about 20 inches fully extended, if not more. Maybe fake leather would be too heavy, but a cordura type of thing (like a duffel bag material) could be the answer.

All this is purely academic at this point, but I thought that throwing the idea out here and seeing if it survives couldn't hurt.

 

[glbeas]

It may be far easier and cheaper to find a fixer upper with a decent bellows and work from there. Re-inventing the wheel is so tedious! Then also theres been a few threads on making your own bellows, look em up. If they don't scare you that may be your best option for building that dream camera.BTW, extreme movements are overrated, most times you hardly need to move much to get what you need. An old but solid field camera may do the trick for you.