Field 16x20" Camera Project

[coisasdavida]

Please allow me to repeat myself and also to share a few things I have been doing trying to get this camera off the paper.
Last year I started to draw a field camera to use 16x20", 12x16" and 8x20" film.
I happened to have 8x20" FP4 and lith film and xray in the other sizes so it was an obvious idea.
Maybe a 14x17" back in the far future, if xray is still around and if I'll ever be able to use all my film.

I already posted in Andreios' thread about banquet cameras, showing my proof-of-concept film holder for 8x20". My design, so far, is based on it. The backs will dettach from the camera as any other would, so if this fails, there is hope and I could go after true holders.

In 2002 I bought some sugar maple to make a crib for my first son. Years later, the maple is still strong and no more children are planned to use it, so last week I used a friend's wood shop and cut the maple into usable pieces.

https://farm8.staticflickr.com/7398/13412878875_8c6b4ea8fe.jpg

This is the bottom of the camera, a 24x24" plataform. There is a center piece on top of which the front standard will ride. It will be a Toyo front standard (my biggest lenses are in Toyo boards already, it makes sense to me).
There will be a sheet of 0.10" aluminum between this center piece and the platform to allow for a double extension.
Planning for 50" bellows, that should allow me to use a 20" at 1:1 and maybe a simple 40" meniscus for regular distances.
The platform will also have to allow for the rear standard to come very close to the front of the camera, one idea I had was to make some round images with the 14cm f/18 on 16x20" film (not sure the bellows will allow for this compression).
For the rear standard I have cut some boards, but I still haven't had time to cut the 45 degree corners and glue it together. This is the boards to make the rear standard.

https://farm8.staticflickr.com/7360/13412982033_c03e67ce14.jpg

After the rear standard is put together, I should make the bellows, right? All the aluminum hardware I'll have to make to attach rear standard to base will have to take in account the thickness of the compressed bellows when the camera is closed, right?

I'm planning for front rise, fall, shift and swing and also at rear swing and tilt. Good enough?

[Dan Fromm]

Modest suggestion, feel free to disregard. If you make your bellows detachable you should be able to make some very simple and inexpensive and, alas, ugly bag bellows.

My simple, inexpensive and ugly bag bellows for a much smaller camera is made from 1.5 mm neoprene sheet as is used for making wet suits. Version one was simply glued with neoprene cement. After a month or so the seams came apart. Try two, which is still holding after more than a year, was glued and sewn. The glue is opaque, keeps light out.

I made mine from two square sheets of neoprene with holes cut to match the bellows frames' openings. Simple as can be, and so far so good. If you decide to make detachable bellows, your bellows frames' size may dictate building the sheets up from strips of material.

Good luck, have fun,

Dan

[Lachlan 717]

Nice work, Dan.

Does the bellow collapse on itself at all (ie. does it stay "bellowed"?)

[Dan Fromm]

Lachlan, you can see it here: http://1drv.ms/1fFhcUg

It doesn't collapse. And as you can see, it doesn't give much extension. This because I didn't need much.

[Lachlan 717]

Thanks, Dan. Very interesting!

[Dan Dozer]

The bigger challenge you will likely have with your bellows being that big is not the overall thickness when it is compressed, it is that a bellows that large (up to 50"long) will likely have sagging problems in the middle. When I designed and built my 8 x 20 camera, the bellows was one of the last things I built. My bellows extends out at about 34" and works very well. Wasn't very difficult to design the front and rear standards to make the bellows removable.

Here's one other thing to consider - focusing a camera that large is a challenge and you will need to use the rear standard for focusing (you won't be able to reach the front standard while looking at the ground glass). I found that having a gear track assembly isn't needed for sharp focussing and the rear standard can just ride by friction on the rear rail to focus. While the full gear track might look nice and a little more professionally done, gear tracks are expensive and in my opinion not needed for cameras this large.

[coisasdavida]

Dan, I like the idea of not having to make a proper bellows.
My trigonometry may be off, but I calculated that I would need two squares with at least 139cm sides to get 100cm extension.
Do you think it is lightweight enough to stay up?
Your suggestion is that I remove it from the camera when closing?

[coisasdavida]

Dan 2,
I was planning to have a few wire supports unfolding from the platform to take the weight of the bellows at long extensions.
I had not planned any gears, I agree the bigger the negatives that less we need them.

[Dan Fromm]

Dan, I like the idea of not having to make a proper bellows.
My trigonometry may be off, but I calculated that I would need two squares with at least 139cm sides to get 100cm extension.
Do you think it is lightweight enough to stay up?
Your suggestion is that I remove it from the camera when closing?

I doubt that a long bellows made to my bag bellows' design -- basically two sheets of opaque material fastened together at the edges -- will work well. I used ten inch (250 mm) squares, maximum extension is around 90 mm. My bag stays up because it is short.

I'm sorry, but if I were you I'd make a proper pleated bellows for use with longer lenses.