Mamiya-Sekor CU f1.8 75mm

[iangreenhalgh1]

Hi folks

I spotted this lens on ebay and decided to grab it as it should make a really good macro lens, perhaps it will also quench my craving for a Jupiter-9 or similar 90mm.




I think the CU stands for 'Close Up' and this lens was used to take pictures of oscilloscope screens, hard to find much info but I found these snippets:

[iangreenhalgh1]

I found a Japanese blog where this lens is mounted on a Graflex, as well as a couple of samples taken on an EOS 5D which look promising:

http://hanano-kaori.cocolog-nifty.com/blog/2008/11/mamiya-sekor-cu.html



I can't read Japanese obviously, but I'm guessing that was shot wide open and although it's hard to judge from the small image, those whiskers look pretty sharp, bokeh is a bit 'shaky' but it looks like it will be a useable lens for me on my EOS 10D and NEX-3.

I think this illustrates the Mamiya housing the lens was taken from:



Looks like Hanano-san mounted his lens in a Synchro-Compur to use on his Graflex:



I think this was taken with the Graflex:



I don't suppose any members here can read Japanese and tell me what Hanano-san has to say about this lens?

[walter g]

Google translate works after a fashion. He really dosen't say much about the lens itself.
http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fhanano-kaori.cocolog-nifty.com%2Fblog%2F2008%2F11%2Fmamiya-sekor-cu.html

[iangreenhalgh1]

Thanks Walter. Seems he says it has severe pincushion distortion.

Looks like I'm on my own with this one and will need to experiment somewhat.

I think I might have a nice mount just suited to this lens.

[walter g]

Looking foward to the test results. Really cool looking lens either way.

[Sevo]

These lenses were part of big, box-like Mamiya/Polaroid CRT oscilloscope (probably medical, as non-photographic sellers usually have plenty of hospital surplus gear) recording cameras. Not rare - one big surplus dealer had hundreds - and correspondingly cheap (when Polaroid spare rollers were more expensive than today, people even bought them for Polaroid back parts and trashed the lens).

They do pincushion by intention - CRTs weren't flat back in the day, the lens compensates for that.

[iangreenhalgh1]

Thanks for that info Sevo, I guess the pincushion can be corrected in Photoshop. I'm mainly interested in this lens for macro work on bellows.

[iangreenhalgh1]

Well I tried the lens on my EOS, it's been raining all the time here so I only managed a couple of shots in the backyard. Back focal distance seems to be around 50mm so it will be tricky to mount for EOS, but it looks promising to my eyes, bokeh is very smooth and it seems quite sharp wide open, amazing build quality, and this one is so mint it looks like it's never been used. Think this will make a good macro lens at least, could be good for portraits too with the smooth oof rendering.

[tikkathree]

Wow, that looks interesting, and more interesting for you than for me I think. Good luck with it.

[iangreenhalgh1]

Aye, the rendering is unusual, definitely looking forward to playing with it further.

[pdccameras]

Interesting lens and images, Ian. If the lens indeed came out of a piece of medical equipment: ultrasound, CAT scanner, etc., it was probably designed with high resolution at a close focus distance and a very flat field. It obviously can cover Polaroid pack film, which was 10.8 × 8.3 cm; 4.25 × 3.25 inch, so you could achieve some cool effects by using this lens as a tilt/shift lens - especially if you add some kind of a "water house" stop or other diaphragm.

Check out this inexpensive (under $10 us) DIY tilt/shift adapter.
http://content.photojojo.com/diy/plungercam-diy-tilt-shift-lens/


Enjoy your cool lens.

Paul

[iangreenhalgh1]

Actually, it has an 8-bladed aperture, forms perfect hexagons so oof highlights could be interesting.

I have thought of using it for tilt/shift but the register is a bit short for that, I am looking at using one of my other MF/LF lenses instead, prime candidate being one of my two Ross Xpress f4 5inch lenses.

I bought a bunch of plungers on sale at 50p each recently, I use em for lens hoods and some of my wierder lens conversions, often come in raher handy!

Thanks for the suggestions Paul.

[iangreenhalgh1]

Managed a few more shots today, these are all wide open:

[iangreenhalgh1]

Some more, mostly f4, a couple at 5.6.

[Attila]

I don't think this is good Ian.

[iangreenhalgh1]

It's not very sharp but I think with the right subject the unusual rendering could be useful.

[Attila]

You have some 'crappy' noname lens compare them I am curious. That for sure I not like at all soft focus lenses. I had Fuji 85mm f4 2 times. I always sold them result never amazed me.

[iangreenhalgh1]

I do indeed have a few crappy lenses. I was interested in this lens for macro work but obviously, too soft, I do think it can perhaps be a good portrait lens though. Hope we get some sunshine soon, hard to take good shots with the terrible weather we are having.

[Attila]

[iangreenhalgh1]

Yes, and I think one major difference will be the ability to stop down the lens to f8 and f11, it might perform rather differently at those apertures than wide open at 1.8. All the shots with it so far have needed the contrast increasign, but I think this could be more due to the lighting than the lens, it is coated, has amber coloured coatings.

I am wondering what optical design this lens employs, it appears to be symmetrical as there are front and back cells that unscrew so it can be mounted in a large shutter, so I wonder what it is, Dialyte perhaps?

Are Mamiya still in existence? Maybe I can email them for info on this unusual optic?

[ColSebastianMoran]

Ian, thanks for posting about this lens.

I have one, exactly like yours, and intend to put it on a DSLR and try it as a macro lens.

Looks like this lens produces high quality images for subjects ranging from a blossom to a face to things a bit larger. Do you have any idea what magnification is the sweet spot for this lens? And, for subjects a few inches across, how is the distortion?

[iangreenhalgh1]

Hiya

I haven't tried this lens again since I posted this thread, need to do so!

I'm afraid I know almost nothing about it, just that it was used in an oscilloscope camera that used polaroid film.

[ColSebastianMoran]

Your photos look pretty good to me. I have experimented quite a bit with the X-Ray Heligons which produce interesting, but very stylized renderings of macro subjects with Nikon F-mount adapters. This Mamiya CU lens seems to give clear and sharp renditions for flowers and head-shots on your EOS camera.

Thinking about this design choices behind this lens: Why is it f/1.8? The build quality is superb; it's not a cheap lens. I think this is a high quality fast lens for recording dim oscilloscope traces onto Polaroid film. Thinking about the sizes of oscilloscope screens vs. Polaroid film, I think this lens is probably designed to be optimal at around 1:2. That would be a big flower blossom onto MF film or a matchbook onto APS-C.

I think it might be an excellent, shallow depth of field, macro lens for flowers. If it gives a sharp image with smooth out of focus backgrounds, that would be interesting.

The photos of the cat from Japan are probably quite far off from the optimum conjugates for this lens.