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Angenieux 48mm G10 Custom L39 Helicoid with LTM Cam ?
Old 03-23-2019   #1
max0ski
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Angenieux 48mm G10 Custom L39 Helicoid with LTM Cam ?

Hello all! I have an idea I wanted to share and just get people to weigh in on it before I go down the rabbit hole and spend hours trying to build this thing.

I have an Angenieux 48mm I use for enlarging and want to convert it to use on my Leica II. I've only seen this lens used for macro work but I saw some photos on flickr the other day of someone who used it at infinity and it looked pretty good, or good enough for me to want to try this.

I'm thinking of finding a for-parts LTM lens that has a cam, stripping everything but the helicoid+cam and long story short just sticking the angenieux on the front (and somehow have it calibrated to sit at the right distance from the negative plane at helicoid-infinity)

I haven't measured the flange focus distance for the angenieux yet (haven't figured out how) but is there anything fundamentally wrong with this idea or does it stand a chance?

Last edited by max0ski : 03-23-2019 at 12:04. Reason: typo
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Old 03-23-2019   #2
retinax
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You'd certainly need to strip the lens of all unnecessary parts like the mounting flange. Measuring the flange/focus distance should be your next step, this will determine if it's possible, then you can make a sketch. You'd need a barrel/helicoid that physically fits, allows access to the aperture control and then there's the discrepancy in actual focal length, Leica standard is about 51mm, which might be ok with this slow lens.
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Old 03-23-2019   #3
max0ski
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This might be a stretch but Im wondering if I can make the angenieux removable, basically make a l39 to l39 helicoid with a cam that doesnt require me to modify the angenieux in any way, Im guessing it would depend on how much space Im left with once I measure the flange/focus distance?
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Old 03-23-2019   #4
retinax
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Seems very unlikely to me, but measure away!
Quote:
Originally Posted by max0ski View Post
This might be a stretch but Im wondering if I can make the angenieux removable, basically make a l39 to l39 helicoid with a cam that doesnt require me to modify the angenieux in any way, Im guessing it would depend on how much space Im left with once I measure the flange/focus distance?
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Old 03-23-2019   #5
Phil_F_NM
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You're going to have to grind the cam of your donor helicoid to match the focus rate of your Angenieux lens. This will be a significant difference. The difference between the two different versions of second generation Summicron, the "rigid" and the dual range is only .3mm. I mention this because that small amount is a very noticeable focus discrepancy. What you want to do is couple a lens that is 3+mm different. It will have a completely different focus rate and once you grind that cam, you're going to have to adjust the helical back to make up the difference. It's possible but not easy to say the least. This is even a very difficult project using an SLR lens with the same nominal focal length AND focusing rate as the Leica standard, that lens being the Super-Multi-Coated Takumar 50mm f/1.4 (scalloped metal focus ring version.) I've measured that optic at least a few dozen times, and calculated that it's focus rate is .02mm from the Leica standard yet I haven't had the machine shop, the materials, the time and the money to make this happen. That .02mm is also the maximum amount of precision I can get from my micrometer.
I'd say, figure out the nominal focal length of your Angenieux, if it can focus to infinity, stick it on a Russian donor and use it as a scale focus lens. Good luck and let us know how you make out with this project.
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Old 03-24-2019   #6
max0ski
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Thanks Phil! This is definitely more complicated than I thought, or I sort of knew this was coming (lol.) I've got a donor 5cm elmar on the way (its optically trashed) but whats nice about this is the focusing helicoid basically just holds the lens like a baby so you can drop out all the optical elements in one go and your left with the helicoid and a huge hole in the middle which will (finger crossing) be small enough for the angenieux (stripped) to fit in. Ill give an update if I get any farther. Thanks again for the help
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Old 03-24-2019   #7
Phil_F_NM
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As long as there are no cracks in that Elmar you can easily polish the elements and have a great little lens. You can get cerium oxide powder or mixed paste for a few dollars and then go to town on those scratches. Once you do this though. You are going down the rabbit hole of buying trashed optics just to bring back to life. It's nice and meditative.
Whatever you decide to do, post some photos.
Phil Forrest
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Old 04-05-2019   #8
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No encouragement ad cams, but Angenieux themselves stated in their PR that the 48mm had 97% contrast at 16 cpm zero vignetting at f5,6 and +0,08% distorion. It transmits between 370 and 700 my. I could not find the lens-flange to focal plane distance.


p.
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Old 05-05-2019   #9
max0ski
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Quote:
Originally Posted by ph. View Post
No encouragement ad cams, but Angenieux themselves stated in their PR that the 48mm had 97% contrast at 16 cpm zero vignetting at f5,6 and +0,08% distorion. It transmits between 370 and 700 my. I could not find the lens-flange to focal plane distance.


p.
Thanks P. I've gotten so busy these last few weeks I've saved this project for later and in the meantime opted for a summar and kept the angenieux as a enlarging lens (after a month of use it just might be too spectacular to convert) but thank you all for the help! If i get around to it ill post and update

Much love,

Max
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Old 05-05-2019   #10
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The trick with these things is always focusing. You could look at a machinist who would seat the elements in a cammed barrel. I had something similar done with a 40mm Contax lens for the [email protected] Sent it to a fellow in Japan who did the machining work. The set up works well, but was neither easy, nor cheap. I had to find a local "correspondent" in Japan to accept the lens and walk it over to the machinist's shop and then pick it up when done and ship it to me in the US as the machinist did no international shipping.

It would probably be easier to either 1) mount the lens into something uncammed that could be used with a mirrorless camera, or 2) mount into a Leica bayonet mount so that you could manually focus using a focusing screen or Visolflex. Neither is for the faint-hearted, but if you like to tinker go for it.
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Old 05-05-2019   #11
xayraa33
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Brian Sweeney could most likely jimmy-rig that Angenieux lens in a J-8 or J-3 focusing helicoid mount and make it work.
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Old 05-05-2019   #12
Erik van Straten
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Many very old movie camera lenses that are now converted to M-lenses are on this moment available in Taiwan and Hong Kong: Angenieux, Kinoptik, Taylor Taylor and Hobson and such. They can be focused on a normal M Leicas, but not on screw mounts. They all seem to be fitted with special adapters and manual modelled setting curves. I own one of those, a Cooke Amotal 2 inch f/2 lens, not a movie lens, but quite like those. It was converted onto a Summicron collapsible LTM chassis. However, I am surprised how precise this converted lens works.

Erik.


before conversion:




After conversion:







Leica MP, Cooke Amotal 2 inch f/2, 2TMY400, printed on Adox MCC 110.


Erik.


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