Scrunchy Bellows

[thuggins]

I have often contemplated an alternative to the pleated bellows. Some sort of support is needed to keep the material clear of the emulsion, so just a bag would not work. Has anyone tried (or considered) a "scrunchy" sort of concept? For those unfamiliar with the term, that is a piece of fabric with elastic inside it.

So the bellows would consist of cloth in the shape of a pyramidal frustrum with elastic bands at each of the four corners. When pulled out it would look like an unpleated bellows. When retracted the material would bunch up around the elastic on the corners which should keep it from sagging against the emulsion.

It would require a fairly thin, flexible fabric and finding something light tight could be a problem. I've wondered about using a dark cloth, but assume those are pretty thick.

 

[Theo Sulphate]

Fabric eventually seems to become a problem, developing pinholes from flexing. Yet the bellows on Speed Graphics rarely seem to be a problem and I've looked at a lot of them. Not sure what the material is.

Ideal I think is the rubber type material used on SX-70... No idea where to get that.

 

[jim10219]

The immediate problem I see is the elastic would pull on the standards and make them unsteady. Also, usually the fabric is seen into the elastic and that would create pinholes. But those problems might be able to be overcome with some engineering. Maybe you could build the standards to be reinforced to withstand the extra pressure and use multiple layers of fabrics, so any pinholes wouldn't matter.

Your idea does inspire me. I'm thinking about a the spring loaded tube, like the ones that connect the back of a dryer to the vent. There are probably problems with that too though. They might require an extra layer of fabric on the outside too.

 

[BAC1967]

I was thinking that something could be made with silicone like these collapsible cups. I don’t know if it can be made dark enough.

https://collapsiblelife.com/collect...ree-portable-graduated-in-bright-colors9-22oz

 

[Dan Fromm]

I have often contemplated an alternative to the pleated bellows. Some sort of support is needed to keep the material clear of the emulsion, so just a bag would not work.

What are you thinking? Name one camera that has a bellows that's so close to the film plane that it might touch the film. Did you mean "out of the light path?"

The simplest bellows I've ever seen is a tapered bag bellows I made from two sheets of neoprene wet suit material and two Cambo lens boards, one for a 2x3 Cambo standard, the other for a 4x5, cut into bellows frames. It won't extend very far, but extends as far as I need it to. The two sheets are identical, are glued to each other, sewn together for luck and taped for appearance. They're glued to the frames.

 

[thuggins]

Ideal I think is the rubber type material used on SX-70... No idea where to get that.

I have searched for something like that also, but with no luck. It obviously exists, but apparently only famous people can get it.

https://fashionmagazine.com/culture...e-maleficent-rubberized-silk-atelier-versace/

The immediate problem I see is the elastic would pull on the standards and make them unsteady. Also, usually the fabric is seen into the elastic and that would create pinholes. Your idea does inspire me. I'm thinking about a the spring loaded tube, like the ones that connect the back of a dryer to the vent. There are probably problems with that too though. They might require an extra layer of fabric on the outside too.

The elastic wouldn't pull any more than the bellows. I've worked with a number of them and they don't like to stay extended. The problem with the dryer hose is that it's round, and the film gate is square. So a tube big enough to cover the gate would have a diameter equal to the diagonal of the frame size. This wouldn't be able to fold into the body.

I was thinking that something could be made with silicone like these collapsible cups. I don’t know if it can be made dark enough.

Black, rubber bellows are readily available as an off the shelf item. Any industrial supply shop that deals with power transmission equipment would have them or could get them. The problem is that they are round, which leaves us in the same situation described above.

What are you thinking? Name one camera that has a bellows that's so close to the film plane that it might touch the film.

Ummmm... All of them?

The simplest bellows I've ever seen is a tapered bag bellows I made from two sheets of neoprene wet suit material and two Cambo lens boards, one for a 2x3 Cambo standard, the other for a 4x5, cut into bellows frames. It won't extend very far, but extends as far as I need it to. The two sheets are identical, are glued to each other, sewn together for luck and taped for appearance. They're glued to the frames.

This may work fine in a plate camera or even one with a dark slide. But in a typical roll film folder (which we are discussing here) any loose bag would sag right onto the film when it was folded.

 

[Dan Fromm]

Dan Fromm said: ↑
What are you thinking? Name one camera that has a bellows that's so close to the film plane that it might touch the film.
Ummmm... All of them?

Look at some of the cameras I own. Kodak Retina, Ensign 820, Speed and Crown Graphics. All fold, all have bellows, none has a bellows that can touch the film.

Dan Fromm said: ↑
The simplest bellows I've ever seen is a tapered bag bellows I made from two sheets of neoprene wet suit material and two Cambo lens boards, one for a 2x3 Cambo standard, the other for a 4x5, cut into bellows frames. It won't extend very far, but extends as far as I need it to. The two sheets are identical, are glued to each other, sewn together for luck and taped for appearance. They're glued to the frames.
This may work fine in a plate camera or even one with a dark slide. But in a typical roll film folder (which we are discussing here) any loose bag would sag right onto the film when it was folded.

So you want to make a roll film folder like a Retina or an Ensign 820 or a Graphic ... and don't want to make or buy a pleated bellows. Why make what you can buy for very little?

And why not tell us what you were thinking of making? The first mention that you're thinking roll film folder is in post #6 about. We're not mind readers.[/Quote]

 

[thuggins]

Look at some of the cameras I own. Kodak Retina, Ensign 820, Speed and Crown Graphics. All fold, all have bellows, none has a bellows that can touch the film.

Yes, that's because they have a pleated bellows and not a bag.

So you want to make a roll film folder like a Retina or an Ensign 820 or a Graphic ... and don't want to make or buy a pleated bellows. Why make what you can buy for very little?

Where is this wondrous source of inexpensive replacement bellows? Please don't keep it to yourself; many people would like to know. The only time I have purchased a replacement bellows was from the Custom Bellows folks in the UK. In addition to the cost of the product, there is the shipping cost to and from the UK (They require the original bellows to insure to proper dimensions). By the time it was all said and done the cost was well over 100 bucks. I'm not exactly poor, but that is still a significant chunk of change. If $100+ is "...very little..." for you, you are fortunate indeed.

And why not tell us what you were thinking of making? The first mention that you're thinking roll film folder is in post #6 about. We're not mind readers.

Judging from the interesting thoughts and ideas that the others contributed to the discussion, it appears you are the only one unable to discern what I was "...thinking of making". Or, perhaps, they really are mind readers!

 

[Dan Fromm]

Tim, do you have cameras with bag bellows? I ask because I do. Some of the bag bellows are not self-supporting, for example old Cambo SC thin leather bag bellows, and others are, for example later Cambo SC bag bellows. My home made tapered bag bellows is self-supporting.

The problem with the ones that collapse is that they can block the optical path. Touching the film isn't a problem even though it is a special case of blocking the optical path.

You might want to take a look at late Cambo bag bellows. Square, no pleats, just two flat sheets of material with a square box of the same material between them. They work in part because there's space between the bottom of the bellows and the rail. If you're going to make a more-or-less conventional folder like a Retina or an Ensign that uses bellows like Cambo's your camera will have to be taller than conventional.

Sorry, I'm absolutely positively not a mind reader. Ask my wife. Ask our cats.

What are you trying to accomplish that can't be done with one of the many old folders on the used camera market?

 

[thuggins]

I got various samples of black cloth and have been experimenting. Four layers of cotton or cotton/polyester blend are typically light tight. This is especially true with a fabric glue that further blocks the opening in the weave. Unfortunately, four layers of cotton is about .040" thick, which is too thick to fit in the space of a typical folder.

Three layers of 40d black PU coated nylon with one layer of Mylar (metalized polyester sheet - I used a "space blanket") is .010" thick and very flexible and light tight. So you could make the outer cover from a sandwich of nylon/Mylar/nylon and use a single layer of nylon for the inner cover.

As is obvious to the observant reader, my main concern is the complexity that comes in with "ribs" and the pleating of a traditional bellows. The dryer hose idea is a very interesting one, but as mentioned above an actual dryer hose would not work. The spring and cover would obviously need to be in the shape of a pyramidal frustrum to match the shape of a normal bellows. High carbon steel wire about .040" can be cold formed pretty easily with a 1/8" to 1/4" radius to make the spring. Easier yet would be to make a series of rectangular wire frames, increasing in size to match the increasing perimeter of the bellows as you move from the lens standard to the film gate. Three to four such frames, spaced along the length of the bellows, should be adequate to hold the shape and hopefully prevent the material from sagging enough to touch the film when the camera is closed.

 

[John51]

Telescopic arms to keep the bag out of the light path?

 

[thuggins]

Telescopic arms to keep the bag out of the light path?

That's an interesting idea and the same concept as using the elastic. Functionally it would be difficult to execute for a couple of reasons. Self erecting folders don't collapse straight back; the lens standard does a bit of a twisty dance when the camera is closed. It could possibly work with the older falling bed folders where the lens slides out on rails. But since the bellows is pyramidal, they still would collapse at an angle.

 

[Luckless]

How, 'outside the box' are you feeling?

One project I was involved with in the past used lightweight inflatable tubes to prop a darkbag up out of the light path of the instruments.

If your dealing with fixed front and rear standards, and they're able to withstand a slight tug without impacting focus, then you may be able to get away with just pulling a tube taut without any elastics or anything. If that doesn't give you your needed clearances on its own then you could take it a step further and rig something based on a suspension or cable stayed bridge style support. [But be wary of your thread connections opening pinholes on you over time.]

However keep in mind while exploring alternatives to the common pleated design scheme that you may be giving up a lot of internal light control. All those pleats make for excellent light baffles to trap stray light, and swapping out from a pleated bellows may result in an increase of lens flair and stray light hitting the film.

 

[thuggins]

How, 'outside the box' are you feeling?

One project I was involved with in the past used lightweight inflatable tubes to prop a darkbag up out of the light path of the instruments.

If your dealing with fixed front and rear standards, and they're able to withstand a slight tug without impacting focus, then you may be able to get away with just pulling a tube taut without any elastics or anything. If that doesn't give you your needed clearances on its own then you could take it a step further and rig something based on a suspension or cable stayed bridge style support. [But be wary of your thread connections opening pinholes on you over time.]

The concern is not with the bag/bellows obscuring the light path when the camera is open. The material can easily be pulled tight enough to prevent that. The concern is the folded material touching the emulsion when the camera is closed.

 

[John51]

That's an interesting idea and the same concept as using the elastic. Functionally it would be difficult to execute for a couple of reasons. Self erecting folders don't collapse straight back; the lens standard does a bit of a twisty dance when the camera is closed. It could possibly work with the older falling bed folders where the lens slides out on rails. But since the bellows is pyramidal, they still would collapse at an angle.

I was thinking on the lines of telescopic portable radio aerials. 4 of them from camera to lens board with the bag on the outside.