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Just converted to EOS: MC ROKKOR 1.2/58. Instant love...
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PostPosted: Thu Apr 26, 2012 10:10 pm    Post subject: Just converted to EOS: MC ROKKOR 1.2/58. Instant love... Reply with quote
Hi there.

I just (almost) finished the conversion of an MC Rokkor 1.2/58 to EOS. I still have to grind down the retention ring to get (close to) infinity, but I was curious about the lens performing on my 5D. So I attached the lens to the cam and shot the conversion tools wide open close to minimum focus distance. Well, it looks quite unique to my eyes. While there is almost no DOF wide open at this distance the bokeh is the smoothest I've seen in my pictures so far. I'm quite impressed. I hope I can manage to get a well defined DOF next time I shoot the lens, maybe at the wedding in two days?

The pictures: Conversion tools and aluminium dust (wo gehobelt wird, fallen Späne), a crop of the alu dust and the lens itself....





PostPosted: Fri Apr 27, 2012 6:41 am    Post subject: Reply with quote
Nice!, thanks for sharing!

Have you taken pictures of the process?.
I got several Rokkors and maybe I would like to try to convert some... Wink

Regards.
Jes.


PostPosted: Fri Apr 27, 2012 7:21 am    Post subject: Reply with quote
Jesito wrote:
Have you taken pictures of the process?.
I got several Rokkors and maybe I would like to try to convert some... Wink

Didn't take pictures, but all you need for the conversion of the 1.2/58 is described here: http://www.cogitech.ca/Rokkor/index.html. The process itself took me about 2 1/2 hours, but still have to invest aome time on infinty.

Different Rokkors may require a different conversion process.


PostPosted: Fri Apr 27, 2012 8:14 am    Post subject: Reply with quote
I don't really understand why people are still doing destructive/non-reversible Rokkor conversions for Canon when there are mount replacement kits available from Leitax and this guy http://www.jimbuchananspace.com/Camera_Services.html (I believe there is even a third source).


PostPosted: Fri Apr 27, 2012 8:42 am    Post subject: Reply with quote
AhamB wrote:
I don't really understand why people are still doing destructive/non-reversible Rokkor conversions for Canon when there are mount replacement kits available.

Not everybody has to understand everything, I myself don't undstand many things other people are doing. Well, such is life... Wink


PostPosted: Fri Apr 27, 2012 9:05 am    Post subject: Reply with quote
No need to destroy, you can adjust infinity by removing the outer ring which will expose 4 screws, just loosen them and adjust focus ring in req'd direction and re-tighten.


PostPosted: Fri Apr 27, 2012 11:43 am    Post subject: Reply with quote
Jesito wrote:
Have you taken pictures of the process?.
I got several Rokkors and maybe I would like to try to convert some...


I made a guide for converting the Rokkor 58mm f/1.2 back in 2007. It's pictured for Sony Alpha, but the same process can be used for Canon as well, and indeed requires less adjustment due to shorter register of EOS vs Alpha. I recommend my guide over the one previously linked, not just for self-promotion but because the other guide advises to sand down the mount unnecessarily, which is both needlessly destructive and also introduces risk of uneven sanding, which could cause tilt.

(Note: After I made my guide, many people have informed me that there is a simpler way to adjust infinity focus on the lens than the one I used, so one may wish to look into that as well. I haven't tried it myself, since this lens now has essentially perfect infinity focus position—calibrated on stars at f/1.2—so I don't want to mess it up. =)

(Note 2: Turns out that the Rokkor 58mm f/1.2 is perhaps the easiest Rokkor to convert. Most others are considerably more difficult.)

AhamB wrote:
I don't really understand why people are still doing destructive/non-reversible Rokkor conversions for Canon


It is possible to convert this lens reversibly as well, I really don't know why the guy chooses to sand down the old mount when there is easily enough adjustment room to get infinity focus even on Sony/Minolta AF without this. (My conversion linked above does not alter the thickness of original parts; a small rim is removed in the process but its function on the lens is cosmetic so original settings can be restored.)

That said, mount replacements may indeed be a good option for the f/1.2 Rokkors nowadays… Back when I did mine I was able to buy the lens on eBay for under €100 so the cost of a replacement mount would have been fairly high compared to the price of the lens, now it's different. Still, there is a certain appeal to doing these conversions rather than just buying more stuff, but for me that applies mostly when I convert a new lens that no guide exists for, it's like puzzle then.

Last edited by Arkku on Fri Apr 27, 2012 2:59 pm; edited 5 times in total


PostPosted: Fri Apr 27, 2012 12:17 pm    Post subject: Reply with quote
Welcome to the club, I love my Rokk's when we start to see FF mirrorless cameras, we will see less destructive mods being done.
I had the problem of deciding if I should have conversions done to match my MC PG 58/1.2 or keep them(HH 35/1.8, QF 50/3.5 macro) stock, in the end I decided to keep them stock and just use them on NEX-7 for now.


PostPosted: Fri Apr 27, 2012 2:47 pm    Post subject: Reply with quote
Does anyone know if is a conversion like this possible for a minolta MC Rokkor PG 50/1.4?
It is probably my favourite lens, and I'd like to use it on my sony without either losing infinity focus or putting extra glass between the lens and the sensor.
I found some that brutally cut off the mount, but I'd prefer not going so hard on the lens (I have other 50/1.4's, so I'd like to convert it, but not at the cost of butchering the lens), and I tried to do it myself, but I can't find how to actually remove the mount.


EDIT:
a conversion like this = similar to arkku's on the 58/1.2


PostPosted: Sat Apr 28, 2012 6:12 am    Post subject: Reply with quote
Thanks Hoacker and Arkku for the pointers and the information.
And yes, I do prefer to avoid destructive conversions.
I used a Leitax kit in the past to convert a Planar to Pentax-k, with excellent results at reasonable price, but sometimes, if the lens has some damage on the mount, a destructive conversion can be fun... Wink

Regards.
Jes.
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