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Dsides
Tinkerer
Username: Dsides
Post Number: 33
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 07, 2010 - 12:05 pm: | 
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I just got a lens that turned out to be much larger than I expected. I was hoping to use it on a 2x3 speed graphic...
The lens reads:
Mamiya / Sekor CU 1:1.8 f=75mm CSI3 No. 13690
It has aperture settings (eight blades) from f1.8 to f22
It has a 70mm screw mount, 55mm diopter, and no focus ring
It appears to focus at infinity only two inches from the mount
Is this for a large format camera? TV camera lens?
Projector? I'm stumped...
(Sorry - no digital camera to post picture with) |
Msiegel
Tinkerer
Username: Msiegel
Post Number: 210
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 07, 2010 - 12:20 pm: |
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In some forums they suspect that CU stands for close up.
Here a 65mm one
http://arukucamera.net/23CrownGraphicClose-Up.html
Here a Japanese site sorry no idea about the text
http://hanano-kaori.cocolog-nifty.com/blog/2008/11/mamiya-sekor-cu.html
Not much help, I know.
rgds
Martin |
Dsides
Tinkerer
Username: Dsides
Post Number: 35
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 07, 2010 - 12:26 pm: |
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Yeah. That's all I could find too. I even poured over "images" for almost an hour until the search was producing images from people in Viet Nam (where aparently "Cu" is a word). ;-) |
Finnegan
Tinkerer
Username: Finnegan
Post Number: 63
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 07, 2010 - 12:32 pm: |
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You have one of these too? Mine is a 65mm f5.6 (to f22) in a Copal Press shutter. My lens is small like an Angulon. I have tried to find out more about it but found nothing. Saw one on eBay but no data from the seller. I haven't tried it on a camera yet. I think my original search for data turned up similar lenses made by Nikon. Not sure what the CU signifies but close-up is one idea and cathode unit is another theory. Thought, for a while, it may have come from a CRT oscilloscope camera.
If you can't use it, are you going to sell it? |
Finnegan
Tinkerer
Username: Finnegan
Post Number: 64
Registered: 09-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 07, 2010 - 12:54 pm: |
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The lens in the aruku link is the same as mine except for the shutter. Now that I saw the 2nd link I am more sure your lens comes from some industrial type camera. It reminds me of the Wollensak 75mm f1.9 crt lens in Alphax shutter that comes from old oscilloscope cameras. I also have a similar lens that is marked Wollensak 2" (52mm) f1.0 4.4:1x crt lens. The seller said this lens could not focus at infinity, only at close-up range. Haven't tried this one yet either. |
Dsides
Tinkerer
Username: Dsides
Post Number: 36
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 07, 2010 - 02:18 pm: |
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Mine has no shutter - which would be ok with a Graflex Pacemaker, except for the focal distance...
I could build a camera around it if it had the shutter! |
Richard1karash
Tinkerer
Username: Richard1karash
Post Number: 1
Registered: 02-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 28, 2011 - 07:18 pm: |
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I have one of these and have been trying for a long time to find anyone else with this lens.
I Googled for the same few pages as you, Dsides, I'm pretty sure it is a macro lens. If we are lucky, it is an oscilloscope lens: fast, high quality, optimized for maybe 1:2 to make an optimal image of an oscilloscope trace onto Polaroid or MF film. It would be one of the fastest macro lenses you'll ever see.
Some oscilloscope lenses are only modest quality. Some have deliberately curved field to match the old curved faces of the 'scope screen. On the other hand, the Nikkor-O 55mm f/1.2 Oscilloscope lens, per Bjorn Rorslett, produces "exceptionally sharp" images at 1:5 (onto 35mm film or FX sensor). We might be lucky, but we'll never know till we try.
I have plans to mount mine on an extension tube about 100mm from the image plane and test it as 1:2. But, it's been waiting for me to get around to it.
I am pretty sure it is not going to produce much of an image on a 2x3 camera at infinity. I suspect it is sharp at close-up range and inferior at infinity.
It is a beautiful lens. Seen periodically on eBay; there's one for sale on eBay UK right now. For $50 maybe; listed a couple of times no sale. |
Richard1karash
Tinkerer
Username: Richard1karash
Post Number: 2
Registered: 02-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 28, 2011 - 10:17 pm: |
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Dsides, what are your other options for a modern general use lens on the "baby" graphic? |
