Movements on a 20x24" - how precise ?

[Falkenberg]

I was playing aroung with a Manfrotto 405 geared head as an inspiration on how movements can be handled, but it made me wonder how precise movement has to be on a 20x24" camera ? The Manfrotto head offers two kinds of adjustments, quick and very fine. I have looked a several differnt smaller cameras and they seem to be very different i how precise the movements are. I have no experience with a format as large as a 20x24".

 

[John Koehrer]

Well, if you want to get really fine, design yourself something with a worm gear setup. I think it would really be overkill for something as crude as a view camera. If you do worm drive make sure you have something in mind to disengage the worm so you're not spending too much time trying to zero the camera.
Think in terms of a trapped threaded shaft engaged with a fixed nut.
I think I've seen something like this on a focusing stage for macro work.

 

[phfitz]

Falkenberg,

If you can get up close and personal with a Calumet C-1 8x10 you will see the focus adjuster is both fast and very fine. It has a round wheels running in tracks, no teeth. Works very well, ultra-fine adjustment and easy the clean.

Have fun with it.

 

[Falkenberg]

I will try to find a Calumet C-1 camera or some pictures of it. I had the chance to work some more with the Manfrotto head and I realize that I had misunderstood the way it works. It has two knobs on each and one of the is the finetuning and the other releases for free rotation. I found the Patent litterature for it and it describes it very nicely (http://www.google.com/patents?id=h6onAAAAEBAJ&dq=5589903). I also had the chance to play with a hydraulic adjusted clamping device. It could also be a fun way to do the adjustments. But it will never be a fast way to adjust, but it will offer extremely good fixing.

 

[epatsellis]

It really depends, how accurate do you want? My cameras have leadscrews for focusing, the next 20x24 I build will have them for movements as well, though I imagine it will add some weight to the camera. For a first attempt, I'd use the philips/chaminox approach, leadscrew driven focus, manual movements.


erie