Who needs sharp corners at F1.2? Stop with the pixel creeping! We need lenses that produce magic, not flat boring shots with sharp corners. This is a welcome addition that I would buy any day of the week instead of the overpriced fat RF 50mm F1.2.
But do not buy any Leica lenses below 35 mm, unless tested. You will normally experience an ugly colour cast on both side of the pictures, and a huge loss of sharpness too. Even some older 35mm summicrons disappoint (around 1968). So, testing is highly recommended.Btw one of my next purchases will be a good RF-Leica M39 thread mount adapter. The 20mm flange focal distance of the RF mount allows to adapt M39 lenses and keep infinity focusing, since that classic Leica mount has a flange focal distance of 28.8mm. I'd like to try some of my vintage M39 lenses on my R5 II, like my 1.4/50mm and 1.8/85mm from Canon (late lenses from Canon's rangefinder era). Adds a bit of radioactivity to my imagessince the highly refractive lens parts were made of thoriated glass...
I have the KF M39 to RF adapter and I can confirm the Jupiter 50mm f/2 works great on a R6 ! Very small lens. It would give even the Devil himself a halo at f/2.Btw one of my next purchases will be a good RF-Leica M39 thread mount adapter. The 20mm flange focal distance of the RF mount allows to adapt M39 lenses and keep infinity focusing, since that classic Leica mount has a flange focal distance of 28.8mm. I'd like to try some of my vintage M39 lenses on my R5 II, like my 1.4/50mm and 1.8/85mm from Canon (late lenses from Canon's rangefinder era). Adds a bit of radioactivity to my images
My experience with vintage thorium lenses that have yellowed is not a good one. I have found both a loss in light transmission and resolution as well as a colour cast.
You dont need to pixel peep to see the issues with this lens. Busy bokeh, soft, hazy, high CA even stopped all the way down. A continuation of Canon's tradition of ........ I hate to say it......... mediocre affordable standard primes. There are cheap zooms that look better at the same apertures/FL than this prime.
The reason why I purchased 2 Canon 7 bodies (one because a lens that interested my was part of the offering) when I returned to film photography parallel to digital photography was that I wanted to delve into the Leica M39 world with the most modern rangefinders ever made for that first 35mm standard mount. But I never made it to Soviet Jupiter lenses, this might be fun, too. I stuck with Canon glass from the late 1950s and 1960s because the best ones of these fast primes combine already quite modern sharpness in the center and good micro contrast with still a very nice vintage character. Canon's 18/85 mm in particular is a real gem and hunted by collectors (I am no collector, I want to use that vintage gear). I needed several years to get a good copy - good means to me: signs of wear are welcome but the optics and mechanics need to be in very good condition.
I think it depends on the grade of yellowing, of course it it is too strong it will interfere too much with the image quality. My lenses are still in a condition in which they can deliver beautiful images.
Luckily, I prefer normal to short tele focal lengths for settings in which I use these old lenses. That said, I got also a 2/35mm LTM lens introduced by Canon in 1963 (https://global.canon/en/c-museum/product/s41.html). This M39 lens has already a very modern character, with decent sharpness in the edges even wide open - and it is beautifully small and light. Of course, a copy in good condition isn't a bargain, if you are very lucky today you get one for about 400 US-$, preferably from Japan.
