Greg
7-Oct-2016, 11:46
I had kept on seeing very fast BUHL projector lenses up for auction for some time at very reasonable prices. Finally found a BUHL OPTICAL 9.0" (229.0mm) f/2.5 projector lens at a price i couldn't pass over. Bought it hoping it would work on my Whole Plate camera.
Lens finally arrived in pretty near mint condition. Front element 3.5 inches in diameter. First off I had to unscrew and remove the long focusing tube off the back of the lens. Had a plastic Sinar "lens board" hanging around which made it easy to cut a hole in it to mount the lens on it. Mounting via the use of a hot glue gun... quick and it easily holds the threads on the back of the lens to the lens board. More importantly this way of mounting it completely reversible by cutting and peeling away the hardened hot glue.
Finally got around to testing the lens:
I always test lenses using the next larger format to get a better idea of lens coverage so used my 8x10 Norma. Mounted the 8x10 on a tripod, mounted my Sinar shutter onto the front standard and then tried to mount the BUHL lens on to the front of the shutter. Problem one... the lens was recessed back a bit into the lens board and rear stuck back just enough to not be able to mount in onto the shutter. Went back home and removed the hot glue and re-hot glued the lens with its rear flush which the back of the lens board. Went back again to our town's Museum's covered porch where i always go back to to test lenses. Set up the Norma with shutter and BUHL on the front. Since the lens has no iris and the Sinar shutter only goes up to 1/60, I needed to attach a 3.0 ND filter to the rear of the shutter (easy since 2 tabs are there to mount filters with). Shot a test exposure. Image attached.
Results:
Optic is no Petzval... but then I knew that
A lot of light falloff
Coverage barely at infinity but it does cover Whole Plate. Looks to be very useable on a 4x5.
Center sharp (looking at original negative), then just gets worse as you go out from the center
At infinity performance not to my liking.
I really want to use the lens on my Whole Plate camera. Will take the front element out and insert a waterhouse stop making the lens a f/4 optic. Will be interesting to see what the optics are and their configuration. Hopefully this will sharpen up the image just enough. If so, will finally epoxy the optic to a real metal lens board.
Comments welcome
Lens finally arrived in pretty near mint condition. Front element 3.5 inches in diameter. First off I had to unscrew and remove the long focusing tube off the back of the lens. Had a plastic Sinar "lens board" hanging around which made it easy to cut a hole in it to mount the lens on it. Mounting via the use of a hot glue gun... quick and it easily holds the threads on the back of the lens to the lens board. More importantly this way of mounting it completely reversible by cutting and peeling away the hardened hot glue.
Finally got around to testing the lens:
I always test lenses using the next larger format to get a better idea of lens coverage so used my 8x10 Norma. Mounted the 8x10 on a tripod, mounted my Sinar shutter onto the front standard and then tried to mount the BUHL lens on to the front of the shutter. Problem one... the lens was recessed back a bit into the lens board and rear stuck back just enough to not be able to mount in onto the shutter. Went back home and removed the hot glue and re-hot glued the lens with its rear flush which the back of the lens board. Went back again to our town's Museum's covered porch where i always go back to to test lenses. Set up the Norma with shutter and BUHL on the front. Since the lens has no iris and the Sinar shutter only goes up to 1/60, I needed to attach a 3.0 ND filter to the rear of the shutter (easy since 2 tabs are there to mount filters with). Shot a test exposure. Image attached.
Results:
Optic is no Petzval... but then I knew that
A lot of light falloff
Coverage barely at infinity but it does cover Whole Plate. Looks to be very useable on a 4x5.
Center sharp (looking at original negative), then just gets worse as you go out from the center
At infinity performance not to my liking.
I really want to use the lens on my Whole Plate camera. Will take the front element out and insert a waterhouse stop making the lens a f/4 optic. Will be interesting to see what the optics are and their configuration. Hopefully this will sharpen up the image just enough. If so, will finally epoxy the optic to a real metal lens board.
Comments welcome