Understanding Bellows Draw
I'm still looking for an old 19th century lens, but am a little confused about focal lengths. When I see that a lens is called "twelve inch," I know the lens itself isn't twelve inches. I've been assuming that the lens needs 12 inches of distance between the lens board and the GG? My Shen Hao HZX45-IIA has only a single bed extension, and the length between lensboard and GG at full draw is about 11 inches. Does that mean I need to be looking for a lens that is 12 inches or less, such as a 9 inch? That cuts down my options pretty quickly if so!
Kent in SD
Re: Understanding Bellows Draw
Kent, the 12" focal length is indeed 12 inches from the nodal point to the film plane (roughly speaking the nodal point is about at the aperture if I recall correctly) so, while you might be able to focus at infinity you certainly wouldn't be able to focus much closer. Of course you might be able to use a "top-hat" lens board and get closer but they have some drawbacks as well! For 11 inches of draw a 240 or 250mm is about as long you can comfortably go.
Re: Understanding Bellows Draw
Hmm. Using a ruler I actually measured about 11.5 inches, bed pulled all the way out to the stop, front standard pushed all the way forward. On the Badger website it says it has 360mm of draw, which translates to about 14 inches. Did my bellows shrink since I last used it? :rolleyes:
Kent in SD
Re: Understanding Bellows Draw
Kent, I just ran into the same problem on my new to me shen Hao, with a 300mm Nikkor Lens. You can get it to work by sidding the front standard all the way down and disengaging the lower screw from the track to swing the bottom of the standard out away from the track slightly. Then tilt the whole mechanism forward and move the standard up to where you want it. I can focus fairly close with my 300mm (almost 12"). It didn't seem really secure, as described in my post below (Shen Hao with 300M). I'm still working on it, as both the camera and the lens are new to me.
Dave
Re: Understanding Bellows Draw
Quote:
Originally Posted by
Two23
On the Badger website it says it has 360mm of draw, which translates to about 14 inches. Did my bellows shrink since I last used it? :rolleyes:
FWIW, you can use a telephoto-design 360 like the Nikkor-T - flange focal distance for that lens is specified as 261mm.
Re: Understanding Bellows Draw
Quote:
Originally Posted by
Oren Grad
FWIW, you can use a telephoto-design 360 like the Nikkor-T - flange focal distance for that lens is specified as 261mm.
Yes, the telephoto designs are made for exactly that. However, recall that I am looking for something like an 1860 Petzval lens to use, not a modern lens. I'm pretty set for modern gear. I'm actively looking for a Petzval style, older than 1880 and with slot for stops. Would also like to get an Aplanat or RR too.
Kent in SD
Re: Understanding Bellows Draw
Quote:
Originally Posted by
Dave Hally
You can get it to work by sidding the front standard all the way down and disengaging the lower screw from the track to swing the bottom of the standard out away from the track slightly. Then tilt the whole mechanism forward and move the standard up to where you want it.
You know, I've had the camera sitting on the desk in front of me. I kept thinking if there was only a way make that front standard mechanism swing forward a few inches I could get at least 12 inches out of it. I just tried the little trick of disengaging the lower screw guide, and sure enough. Looks like about 15 inches! It is a little shakey as the front is held in place by two small pinch nuts though. I think it might be enough to hold a brass lens if I tighten it enough. Or, even tie a string from the front standard to the rear to keep it from falling forward, LOL. It doesn't have to be pretty; it just has to work. :D
Thanks!
Kent in SD
Re: Understanding Bellows Draw
Kent, If that brass lens is fairly heavy, I would be very careful with it out at full extension. I had problems with it holding while I cocked the shutter on my lightweight Nikkor 300M. Granted, it was my first time out in the field with this camera, and I was kind of rushing, but I had to stop and refocus twice because the lens moved while I was closing the focusing lever and cocking the shutter. I have not had a chance to look into the problem closer, so it may turn out that I didn't do something I was supposed to do, or another solution the the problem.
Good Luck,
Dave
Re: Understanding Bellows Draw
Quote:
Originally Posted by
Two23
Yes, the telephoto designs are made for exactly that. However, recall that I am looking for something like an 1860 Petzval lens to use, not a modern lens. I'm pretty set for modern gear. I'm actively looking for a Petzval style, older than 1880 and with slot for stops. Would also like to get an Aplanat or RR too.
Fair enough. So the answer to your original question "Does that mean I need to be looking for a lens that is 12 inches or less, such as a 9 inch?" is "yes".
