mirekti Posted January 3, 2022 Share #1 Posted January 3, 2022 Advertisement (gone after registration) In addition to my M lenses I own an R Cron 50mm which is used for video and this is a perfect match to Iscorama pre 36 as one can tell from the photo. I wondered if it is technically possible to upgrade its iris from six blades to 9+ rounded blades (the more the merrier) without rehousing the lens as the original housing is perfect for my needs. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/328044-iris-%E2%80%9Cupgrade%E2%80%9D-in-summicron-r-50mm/?do=findComment&comment=4344157'>More sharing options...
Advertisement Posted January 3, 2022 Posted January 3, 2022 Hi mirekti, Take a look here Iris “upgrade” in Summicron R 50mm. I'm sure you'll find what you were looking for!
a.noctilux Posted January 3, 2022 Share #2 Posted January 3, 2022 Hello, nice idea. I'm fan of circular iris myself, in my still pics. Never heard that it's possible to replace iris with round aperture ... I just use lenses built with round aperture when I need, Summarit 1.5/50 some Jupiter 3/8 LTM mount for example. 👇 Why don't you ask repairer or Leica themself. I think that if you pay the price asked (if possible), nothing is impossible. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/328044-iris-%E2%80%9Cupgrade%E2%80%9D-in-summicron-r-50mm/?do=findComment&comment=4344186'>More sharing options...
Michael Geschlecht Posted January 4, 2022 Share #3 Posted January 4, 2022 Hello Mirekti, I think that many single lens reflex camera lenses are fitted with the smallest number of diaphragm blades necessary to produce the image structure that is desired. This is so that there will be the least number of moving pieces when operating the lens's stop down mechanism. Best Regards, Michael 1 1 Quote Link to post Share on other sites More sharing options...
mirekti Posted January 4, 2022 Author Share #4 Posted January 4, 2022 9 hours ago, Michael Geschlecht said: Hello Mirekti, I think that many single lens reflex camera lenses are fitted with the smallest number of diaphragm blades necessary to produce the image structure that is desired. This is so that there will be the least number of moving pieces when operating the lens's stop down mechanism. Best Regards, Michael Thank you. Do you believe (if physically possible) a replacement of six iris to 9+ would bring undesirable rendering? I am not sure I quite understood why six was chosen other than either IQ or cost savings or it was a trend. There are lenses which are 50+ years old with many blades yet still work so I don’t think moving pieces count was the concern. Quote Link to post Share on other sites More sharing options...
Michael Geschlecht Posted January 5, 2022 Share #5 Posted January 5, 2022 Hello Mirekti, I think that by reducing the number of operating/moving parts in the automatic stop down diaphragm: That a more reliable mechanism could be made. I think that a 6 bladed iris is commonly used on a lot of automatic stop down Leicaflex lenses. I would think that a significant amount of work might have to be done to change a 6 bladed mechanism to more than 6. Best Regards, Michael 2 Quote Link to post Share on other sites More sharing options...
adan Posted January 5, 2022 Share #6 Posted January 5, 2022 (edited) It is probably possible (depending on one's bank account). It will require non-trivial surgery, and custom-built parts. It is not just a question of adding more blades (which themselves are not as simple as they look), but also modifying the adjustment mechanism to operate 9 blades. At the barest of minimums, you'd need: - some mathematical design work, to get the curves and thicknesses right. - someone to laser-cut or 3D print the 9 new blades (the 6 original blades would go in the trash). Which have to be very smooth to avoid jamming against one another, and very precise to accurately produce the correct opening for a given amount of angular movement. And will need pivot pins and actuator pins at specific locations. - at least two (front and back) support/swash plates, each with 9 slots and pivot points, to lever the blades into position as the aperture ring is turned. The diagram here gives an idea of how the moving pieces function and fit together - I suspect the R blades will have the L-shape in the third illustration: https://www.tanguayphotomag.biz/colour-temperature-2/the-iris-diaphragm.html I suspect the cost, as custom hand-made work, would be about 2-3 times the original cost of the 50mm itself, since they are pretty cheap these days. The upside is it would be easy to remove the click stops (if desirable for video) during the custom refit. Edited January 5, 2022 by adan 1 1 Quote Link to post Share on other sites More sharing options...
Michael Geschlecht Posted January 6, 2022 Share #7 Posted January 6, 2022 (edited) Advertisement (gone after registration) Hello Mirekti, Andy's advice is very good, as usual. Altho I would keep the 6 diaphragm blades "just in case". Another option is to get an "M" bayonet mount 11819, Version IV 50mm f2 Summicron which comes in both 8 blade & 10 blade versions. It is optically pretty much the same lens as the second version of the 50mm f2 Summicrn-R & it is probably less work to adapt. Best Regards, Michael Edited January 6, 2022 by Michael Geschlecht 2 Quote Link to post Share on other sites More sharing options...
mirekti Posted January 6, 2022 Author Share #8 Posted January 6, 2022 (edited) 35 minutes ago, Michael Geschlecht said: Hello Mirekti, Andy's advice is very good, as usual. Altho I would keep the 6 diaphragm blades "just in case". Another option is to get an "M" bayonet mount 11819, Version IV 50mm f2 Summicron which comes in both 8 blade & 10 blade versions. It is optically pretty much the same lens as the second version of the 50mm f2 Summicrn-R & it is probably less work to adapt. Best Regards, Michael There is a catch, though. I prefer R 50mm as in addition to it I own a 2x APO extender which in essence gives me 50mm f/2 and 100 f/4. A "minimalistic" two lens combo set. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Edited January 6, 2022 by mirekti Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/328044-iris-%E2%80%9Cupgrade%E2%80%9D-in-summicron-r-50mm/?do=findComment&comment=4346278'>More sharing options...
AZN Posted January 6, 2022 Share #9 Posted January 6, 2022 22 hours ago, adan said: I suspect the cost, as custom hand-made work, would be about 2-3 times the original cost of the 50mm itself, since they are pretty cheap these days. The upside is it would be easy to remove the click stops (if desirable for video) during the custom refit. You can easily do this yourself. Remove the rear bayonet flange and take out the tiny ball-bearing which is beneath the flange which provides the "clicks". Discovered this back in the "Leitax" days (Leica R lens to Nikon F mount conversion): http://www.leitax.com/leica-lens-for-nikon-cameras.html Quote Link to post Share on other sites More sharing options...
mirekti Posted January 6, 2022 Author Share #10 Posted January 6, 2022 (edited) 6 hours ago, AZN said: You can easily do this yourself. Remove the rear bayonet flange and take out the tiny ball-bearing which is beneath the flange which provides the "clicks". Discovered this back in the "Leitax" days (Leica R lens to Nikon F mount conversion): http://www.leitax.com/leica-lens-for-nikon-cameras.html Thanks, but the clicks are of least importance to me at this point. I haven’t checked your link, but this is “the right” way to do it: https://youtu.be/dZPT3TkEqdo Edited January 6, 2022 by mirekti Quote Link to post Share on other sites More sharing options...
Ornello Posted January 6, 2022 Share #11 Posted January 6, 2022 On 1/3/2022 at 8:28 AM, mirekti said: In addition to my M lenses I own an R Cron 50mm which is used for video and this is a perfect match to Iscorama pre 36 as one can tell from the photo. I wondered if it is technically possible to upgrade its iris from six blades to 9+ rounded blades (the more the merrier) without rehousing the lens as the original housing is perfect for my needs. I honestly would not bother. Just get an M lens. It will probably cost less. Quote Link to post Share on other sites More sharing options...
mirekti Posted January 6, 2022 Author Share #12 Posted January 6, 2022 (edited) 27 minutes ago, Ornello said: I honestly would not bother. Just get an M lens. It will probably cost less. Well, I do have many M lenses to go with, and old Russian Jupiter 8 and Jupiter 9 with many blades (my 2nd favorite setup), but it requires a cage and additional hardware. Summicron R is a quick run and gun combo. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Edited January 6, 2022 by mirekti Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/328044-iris-%E2%80%9Cupgrade%E2%80%9D-in-summicron-r-50mm/?do=findComment&comment=4346774'>More sharing options...
Ornello Posted January 6, 2022 Share #13 Posted January 6, 2022 1 hour ago, mirekti said: Well, I do have many M lenses to go with, and old Russian Jupiter 8 and Jupiter 9 with many blades (my 2nd favorite setup), but it requires a cage and additional hardware. Summicron R is a quick run and gun combo. I see. I would just use the lens as is. Quote Link to post Share on other sites More sharing options...
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