Since I have one of these in excellent condition and it works well with film, and I now have a 5DII, I wondered if anyone had tried using this on Canon FF.
I know about the need to rid it of it's aperture link, or at least to reduce it. Can this be done in a way to still make it useable on my old LX?
It will still work fine in manual mode, just like older M42 screw mount lenses with a M42 to K adapter. Removing the aperture control lever means that the camera can't control the aperture, as it has to for auto-aperture (i.e. when the camera stops down the aperture as you take the photo), and Tv and Program modes won't work, because the camera can't open or close the aperture. I sold my LX system many years ago, but I can try it on a few other bodies. ...[time passes]... the match-needle system on my K2 seems to work fine in manual mode, but not Auto, the Auto mode on a ME works fine, and the battery on my SuperProgram is dead.
I did those quick tests with a modified SMCP-A 50/1.7, and I also have modified SMCP 18/3.5 and SMCP-M 135/3.5 lenses. In the past, I modified a SMCP 200/2.5 and later sold it (with full disclosure and no effect on price) when I replaced it with a Canon 135/2L and 1.4x Extender.
I found this lens (Pentax SMC-A 20 2.8) at home, my father bought it years ago. Now that I will start shotting video with my 5D2 I'm wondering if I should use this lens. So my first question is:
How is the quality of this lens?
And are there any good adapters (canon ef mount) you can recommend?
I used to own this lens a long time ago when I was a major "Pentax kid". I never had any negative issues with the SMC-A 20/2.8.
Most of the Pentax A series lenses were really good some were wonderful. I had a lot of this stuff and three LX bodies. The A* 85/1.4 was amazing. Perhaps the finest lens I have ever owned. The A* 200/2.8 ED and the A* 400/2.8 were great as well.
I would not be at all surprised that the Pentax SMC-A 20/2.8 has better IQ than the Canon 20/2.8 EF. Adaptors can be found. Snipping off the aperture lever is a sort of big step: it breathes more life into the lens if you shoot with Canon bodies, but the Pentax crowd will frown at you though.
I haven't used the SMCP-A 20/2.8, but I know that it has a very good reputation. Here's what Alex's BOA Gallery had to say about SMCP 20's (BOA is no longer online at http://home.att.net/~alnem/html/equipment_review.html)
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20mm
Among f2.8 versions of K, M, A, F, and FA lens, A seems to be the best with excellent contrast, color rendition, barrel distortion. OTOH, it's not as good in resolution, coma aberration and contrast in the corners as K15/3.5 or K18/3.5, even closed down.
FA version is said to have the same optical formula as the A version, and to be very sharp in the center when stopped down. Not much vignetting , but slight "droplet" distortion was mentioned once. All 20mm lenses are said to have great build and prices to match.
K20/4 and the M20/4 produce very slight distortion. K20/4 is also known to flare. However, when comparing K20/4 to K18/3.5, Nikkor 20/2.8 AIS (current model) and Tokina 17/3.5 (current model.), the K20/4 still beats them in every aspect, especially flare control.
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You can read many more comments about the -A 20/2.8 and other Pentax lenses at Stan Halpin's site: http://stans-photography.info/
I had a Pentax 20/2.8 (the last version of the manual focus). Nice build quality, great color and contrast, but the corner sharpness wasn't great. It also hit the mirror on my Kodak SLR/c anywhere near infinity, which means that it likely to happem much sooner on a Canon 5D/II.
I don't have the SMC 20mm f2.8, but i do have the SMC K 20mm f4 and it's a great little lens. A bit soft wide open, but it clears up very nicely by f8 (f5.6 is decent too). Very small, quite contrasty a fine piece of glass. They're both quite rare.. not much out there on the web and they rarely turn up on ebay.
That's the good news, the bad news is, like others have said, you have to file the metal aperture tab and a fair bit of the plastic tab down to clear the mirror. That will get you rolling, but unfortunately not give you infinity focus. The back assembly of the lens hits the mirror near infinity - i can feel it push up against the mirror on my 5DII when focusing towards infinity in live-view mode.... So you'll have to grind the mirror to get infinity. I haven't ground my mirror yet........
Perhaps the f2.8 is different? So count on definitely grinding the tabs down, and probably the mirror too.
PhotoMaximum wrote:
I would not be at all surprised that the Pentax SMC-A 20/2.8 has better IQ than the Canon 20/2.8 EF. Adaptors can be found. Snipping off the aperture lever is a sort of big step: it breathes more life into the lens if you shoot with Canon bodies, but the Pentax crowd will frown at you though.
I've seen coke bottles with better IQ than the Canon EF 20/2.8. It's alright on EF-S but a dog on FF.
The Canon EF 20/2.8 is one of the "oldest" lenses in the Canon EF lineup: way overdue for a new version.
Like many Canon users I was planning (and saving) for better alternatives to Canon wide lenses. I have several and the IQ on all of them is so-so. The new 17 and 24 TS-E lenses look incredible though. I was thinking about the new Distagon but one of the new TS-E lenses will the ticket. Not exactly cheap though...
