Bellows geometrics

[Steven Scanner]

I’ve made a DIY camera (no reproduction, no standard dimensions). All I’ve got is the front standard size, the rear standard size and the base length. I’ve made a paper version that works, but it’s a bit to short and the dimensions are a bit off, due to the zigzag pattern that doesn’t line up.

I want to make one out of blackout curtain and cardboard (or something like that), but I want this one to be perfect. How do you determen the dimensions?

I made the paper version like this: first I drew a trapezoid with the length of the front standard at one end and the length of the rear standard on the other end. Distance bitween them 1 ½ the base length. Then I did the same with the sides and lined the edges up, forming a Chinese fan. Next I drew a zigzag pattern over the edges of the line. A 90 degree zigzag, 45 degrees offset from the lines. Than I drew parallel lines from every corner of the zigzag pattern to the other side. (I’ve got pictures, but have to look into my archives for them)
What I realised afterwards is that I forgot the part that connects to the camera. I need flaps of cloth to connect to the camera. Also, how many segments do I need?

When unfolded, every segment is at a 45 degree angle. I used Pythagoras to determen the length of the unfolded bellows. Length of the base quared, plus LOB squared and than quare root, comes to 1,41 times the length of the base. I used 1 ½ times so in theory the bellows should never overstretch. Is that right, or should I need another formula?

[Steven Scanner]

The camera can tilt and shift. I would need some extra length on the bellows to do that. Question is, how long?

[ruckusman]

There is a helpful PDF available at this site

http://www.jbhphoto.com/articles/bellows/bbuild.htm

I haven't included a direct link to the PDF as a courtesy to the author.
He has some preface remarks and copyright information on the page

peace out

Glenn

[Steven Scanner]

That's it! Thanks.

[Andrew O'Neill]

There is a helpful PDF available at this site

http://www.jbhphoto.com/articles/bellows/bbuild.htm

I haven't included a direct link to the PDF as a courtesy to the author.
He has some preface remarks and copyright information on the page

I used the same pdf to make a bellows for my ULF camera. Made the process easy to understand.

[ruckusman]

Yes a big shout out to J.B. Harlin (I can't find his first name anywhere on his site)

If he's not a contributor here already he should get the honorary doctorate equivalent just for that bellows making guide - it's an epic contribution to LF

peace out

Glenn

[Jim Graves]

There are also some pretty good You Tube videos (search for "making camera bellows".)

[Steven Scanner]

Thank's mister Graves. For those who are intersted:

http://www.youtube.com/playlist?list=PL9CBE9CBB9806F2BD