16x20 Rapid Rectilinear - too big?

[goamules]

I wanted to try a rapid rectilinear on my 8x10 Century studio, and got an unamed one that is ingraved 16x20. I figured the center would be very sharp, and the extra coverage would just be "equity". I think I got too big a lens, there's not enough bellows to use the extimated 28" focal length. I can extend to about 25". It has great glass, is there any way I can use it that I"m not thinking of? Mount it on the end of a coffee can, attached to the camera front?

[Ron Marshall]

There are top-hat lens boards, but with a heavy lens on an extender board you will be putting a lot of stress on the front standard.

[erie patsellis]

Way too big, as a public service, I'd be happy to shoot it for you and let you know, of course. Actually, for shooting on an 8x10, you'd want a 6 1/2 x 8 1/2, part of the "magic" is using a format larger than the lens is designed for. In all seriousness, I have a 16x20 camera I'd love to shoot that lens on sometime.


erie

[Mark Sawyer]

You could put a negative diopter on the front. To some extent, that would make it a different lens, and I presumptiously suppose it may end up being less or more appropriate to your ends. If that makes sense...

[David Vickery]

How did you estimate the focal length of the lens? I could build you an extension board, as well could a lot of other people, including maybe yourself, but as Ron asked, is your front standard strong enough to handle it? How heavy is the lens for your camera?
If not, can you use a second tripod to support the front standard while using this lens?

[Turner Reich]

Jack the back. Make a back extension, Dorf used to make and sell them. It's just four pieces of wood like a box with no top or bottom that goes between the back and the film back. You will have to make one set of attachments or clips.

[Ole Tjugen]

A normal focal length for 16x20" would be 640mm - for the equivalent 40x50cm format, at least. That's just a little over 25", so should only require about 24" bellows at infinity.

Oddly enough, that's what I found when I tried my 640mm Suter Aplanat Ser. B no 6 on the 8x10" Gandolfi: 29 3/4" bellows is plenty. :p

[Scott Schroeder]

Garrett, I'd be more than happy to find the correct bellows length. :)

I'll even send a plate back with it! :)

[goamules]

Thanks for the ideas. To answer some questions; I measured focal by getting a window image to the wall. My Century camera is very robust and the front should hold the lens (I already use a much larger petzval). I was trying to draw up an extention board last night, even thought of using plastic pipe (but prefer a better looking job). Jacking the back sounds interesting too, I'll think on that one.

I'm going to cogitate on this one a while. To those interested, I may sell it (or trade for another, smaller period RR) after a while. I will keep you in mind.

Hmmmmm....need bigger camera or front, or back ext......

[Gene McCluney]

It would be easier to make a so called "top hat" lensboard than an extension back for your century. The easiest way to make a top hat lensboard is to go to a hobby store that sells small unfinished wood craft items and look for a box of the approximate size. I have seen frequently, little hinged top boxes in raw wood. So, take the hinge and top off the box, and use the bulk of the box glued to a flat lensboard. The bottom of the box becomes the front of the protruding part of the lensboard, on which you mount the lens. Of course you have to cut out a hole on the original flat lensboard equal to the inside diameter of the box you are mounting to it. Spray paint it all flat black. To attach box to lensboard, use glue and screws from the backside of the original flat lensboard.

[goamules]

Thanks Gene, good tip. I'll go a-looking.