Need help with a LF convertible lens

[Sergeant1989]

Just purchased a LF/MF lens off of the famous online auction site and need help figuring it out. Lens/shutter combo is a super crisp Regno shutter with what appears to be 2 removable lens elements with the front lens marked as follows " 4 1/4" 6 1/8" Rapid Orthographic F8". The aperture scale on the face of the lens has 3 scales as can be seen in the attached picture. What I am trying to find out is what are the focal ranges of this lens and how would I achieve them. I currently own a nice 210/365mm convertible lens that shifts between the 2 focal lengths by removing the rear element. Any information provided would be greatly appreciated. Thanks

[Jim Galli]

The first thing you need to know is the aperture scales provided are obsolete, but usable with some interpretation. f16 is the common denominator with our modern scales. Then you need to ignore the other numbers and count stops up or down. ie.it says f8 next, but that's one stop, or f11. f4 is our f8. etc. Then ft. bk. mean front or back element. So if you're using both elements together, use the bottom scale. Back element alone, just take the front element out and use the rear one by itself and use the 'bk' scale. "When using the front element, take the back one out and put the front one in the back. Then focus and use the 'ft' scale. Looks like front is 18" by itself. Back is 14" by itself, and combined is the 6 1/8" maybe? Not sure what the 4 1/4" is about. Put it on a camera, focus on infinity with the various possibilities, and tell us.

[E. von Hoegh]

Jim, 6 1/8"x4 1/4" is the plate size. It looks like the lens is an 8" which converts to 14" and 18".

For the OP, if your other convertible is a Schneider, you remove the front element, not the rear element to convert it.

[Bob Salomon]

=For the OP, if your other convertible is a Schneider, you remove the front element, not the rear element to convert it.

And if it is a Rodenstock Sironar you leave the front element in and remove the back element to convert it. This also protects the shutter blades from dust/dirt/sand/moisture/etc. when shooting outdoors which you almost have to when the lens is converted.

[Jim Galli]

Makes perfect sense. I thought 6 1/8 a bit shallow for 14 and 18.

[Sergeant1989]

Too all who took the time to post thank you for all of the information provided to me on this vintage lens. Other then not having the back flange to mount it on a lens board at this time that I hope to find one that fits in the near future I at least have an understanding of this and my other convertible lens. Peter

[E. von Hoegh]

A flange for a Regno shouldn't be difficult, there may be others that fit. I bet Jim up above would know....

[Jim Galli]

A flange for a Regno shouldn't be difficult, there may be others that fit. I bet Jim up above would know....

Nope. Not so easy. Regno's were before Wollensak sort of standardized things like 3's amd 4's and 5 Betax' etc. It's not a terribly valuable lens. If you're using a wood lens board system, cut a hole that fits tight to the threads and add a bit of hot glue. That can get it in use until a proper flange comes your way.