charles_wood Posted March 2, 2009 Share Posted March 2, 2009 <p>Having started the transition to digital several years ago, my Pentax 645n has pretty much been unused along with a very complete collection of MF primes plus a Pentax MF 80-160mm zoom. I saw an ebay auction for a Pentax 645 to EOS adapter and decided to see just how well the MF lenses would perform on my XSi.<br> Obviously there is a multiplication factor but adjusting the image in the frame of the Pentax 80-160 to match frames from my 70-200 F4L, the Pentax wins by a small but noticeable margin and seems to be slightly more contrasty. My 200mm Pentax is amazing in terms of the amount of fine detail and textures it delivers in spite of being a very old series one for a Pentax 67 that I'm using with a 67 to 645 adapter attached to the 645 to EOS adapter.<br> While certainly not as flexible as lenses specifically made for the EOS bodies, the clearly defined images and complete freedom from CA, and total edge to edge sharpness is stunning.<br> How anyone else tried this with the same results? Or with any other adapters and brands of MF lenses?</p> Link to comment Share on other sites More sharing options...
sarah_fox Posted March 3, 2009 Share Posted March 3, 2009 <p>Charles, I haven't tried it, but I'd be very interested in seeing a sample, if you would be so kind as to post one. I'd be especially interested in seeing a 100% crop from the 200mm. (If you do post this... THANKS! :-)</p> Link to comment Share on other sites More sharing options...
anthony_hicks Posted March 3, 2009 Share Posted March 3, 2009 <p>Very interesting Charles, thanks for posting. I looked into the possibility of this a while back but at the time I didnt persue it...</p> <p><a href="http://www.photo.net/canon-eos-digital-camera-forum/00RATZ">http://www.photo.net/canon-eos-digital-camera-forum/00RATZ</a></p> <p>I still shoot with my Pentax, albeit not so frequently these days, but the lenses are superb and deserve more use. It sounds like I have a similar 645 kit to you too (55 / 75 / 80-160 / 200). It was the potential use of the 55mm on my 450D that particularly interested me, have you tried this lens with your adapter?</p> Link to comment Share on other sites More sharing options...
anthony_hicks Posted March 3, 2009 Share Posted March 3, 2009 <p>Incidentally, are you on full frame or crop?</p> Link to comment Share on other sites More sharing options...
ken schwarz Posted March 3, 2009 Share Posted March 3, 2009 <p>There were at least two generations of the Pentax 67's 200mm lens. I've read that both were good, but that the later one was better. I've seen lots of superb examples of astrophotography through both, and there are few applications more demanding on optical quality. I'd love to see how they came out for you with your adapter, so please post the results if you have a chance.</p> Link to comment Share on other sites More sharing options...
chrisjb Posted March 3, 2009 Share Posted March 3, 2009 <p>Not pentax, but have occasionally used my Hassy lenses on 20/40d, but as my adapter was giving me Inf at 30 feet on the distance scale, made predicting distance for DOF awkqard. bodies have been idle tho. Using on the Xsi would on ly use the very center of the lens, even more cropped than 35mm lenses I presume ? Now I think you prompted me to try the lenses on my 5d, only go from 50mm to 150mm never did need longer. be good to see sample of a longer FL. Do you get inf at the inf point of the distance scale? I have found using the Hassy ext tubes work well too :)</p> Link to comment Share on other sites More sharing options...
charles_wood Posted March 3, 2009 Author Share Posted March 3, 2009 <p>I'm doing a hike tomorrow to The Wave. I'll take a couple of the Pentax lenses with me and do some comparision shots. My Pentax collection consists of a 35, 55, 75, 80-160 and a 105 and 200, the latter two being 67 rather than 645 lenses. <br> The XSi is crop, APS sensor size.</p> Link to comment Share on other sites More sharing options...
charles_wood Posted March 5, 2009 Author Share Posted March 5, 2009 <p>My trip to The Wave didn't work out due to scheduling problems. I did some tests this morning and I'll try and post some files over the weekend but here are my preliminary, not to scientific, eyeball findings based on full screen and 100% observations. RAW files were converted in CS4. No sharpening added beyond default, black and white levels were matched, no change to native midtone settings, color temps were matched:<br> Pentax 35mm is sharper, edge to edge than the Canon 17-40mm F4L with less CA.<br> Pentax 55mm is sharper than long end of Canon 18-55mm IS kit lens. No visible CA.<br> Pentax 80-160 at approximately 120mm setting is marginally less sharp than Canon 70-200 F4L at similar equivalent setting. Not unexpected as the 70-200 is considered one of Canon's sharpest lenses regardless of cost. No visible CA on either.<br> The Pentax lenses were cooler in look in spite of adjusting color temp in the RAW converter to identical settings. The Canon glass seemed to be considerably warmer in look.</p> <p>More to come.</p> Link to comment Share on other sites More sharing options...
anthony_hicks Posted March 11, 2009 Share Posted March 11, 2009 <p>Still dithering over buying an adapter here :o)</p> Link to comment Share on other sites More sharing options...
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