Mounting a Lens to the Gran View

[dazedgonebye]

Hi,
Starting a new thread because I need help.

I'm trying to get the 75mm lens mounted to the Gran View I bought. The problem is that it will not focus more than about 8 inches away from the front of the camera.
I removed the lens from the mount and I find that I can get infinity with the lens well back in the mount. The shutter is about half way in to the throat of the lens cone.
No amount of mounting error could cause this...we're talking a good half inch off.

I tried mounting a 90mm lens, thinking that perhaps the cone was not made for 75mm after all, and it is not long enough to focus the 90mm lens. I have to hold it and the mount well away from the cone before I can focus.

So, I'm not sure what to think.

Any ideas?

[dazedgonebye]

One additional bit of information.

The flange distance measures about 70mm at its minimum and 78mm at its maximum.

Why the heck would the lens need to be closer than 70mm?

[Gem Singer]

Perhaps it was made for a 65mm lens?

[dazedgonebye]

Perhaps it was made for a 65mm lens?

If that were so, wouldnt te 75mm lens need to be further away from the film plane instead of closer?

[EdWorkman]

From the previous thread:
two helices
#1 sets the lens at the proper distance for its focal length and is locked off.
#2 varies the focus of the lens.
Does that fit into this query?
Can you shift the base point of the lens, as for "helix #1", or is the plate you made in place of the first helix? Can you show us a pic of the lens with mount?

[dazedgonebye]

The helical is as you describe, but the lens wont focus no matter how close in it is adjusted....by 10mm or more.

[Gene McCluney]

The problem is that every different "brand" of 75mm lens will have a different point at which it focuses. If you did not mount the particular brand (Schneider, Rodenstock, Nikkor, Fuji, etc) of 75mm then you may be out of luck. Do you know what "brand" the camera helix was designed for? I was afraid you might run into this problem with an inexpensive "off brand" of plastic helicoid focusing camera.

On a bellows equipped view camera it doesn't matter as the bellows has almost infinite adjustment.

[dazedgonebye]

No idea of the intended lens except to say that it is copal 1 and its intended for a flange distance of between 70 and 78mm flange distance.

[Gene McCluney]

The "theoretical" flange distance for a 75mm lens at infinity should be 75mm, but in practice different lens designs place the infinity distance sometimes differently. If you can get a sharp image across the whole frame at SOME point of distance between the camera and the lens, then the lens is OK, just not suited for your special application.

[jb7]

My 65mm ƒ/8 Super Angulon has a flange to focal plane distance of 70.5mm at infinity-
looks like the cone might be for a 65mm...