Firstly, the disclaimer: For anyone who gets upset by extremely non-scientific tests and generalisations: Look Away Now! This is a test of a sample size of 1 photo, from a sample size of 1 lens. Nothing rigorous nor scientific is inferred nor implied. For the rest of you, here's what happened. I had a 220 roll of Portra 160 in my Mamiya 645AF, with 4 shots left on it, that I wanted to process. So why not do some side-by-side testing of some lenses I seem to have collected? The candidates are (verbatim from filter ring, to date versions): Mamiya-Sekor C 45mm 1:2.8 N (sn 165xx) Asahi Opt.Co. Japan SMC Pentax-6x7 1:4 45mm (sn 857xxxx) Pentax 67 on adapter (I don't actually have a P67 body, and it won't fit on my Pentacon 6, so m645 is all I can use this for currently). Carl Zeiss Jena DDR (red)MC Flektogon 4/50 (sn 1091xxxx) Pentacon six, on adapter (beautiful Schneideritis on this one, it's photogenic in itself) Mamiya-Sekor C 1:3.5 f=35mm (sn 162xx) The scene was facing southeast ish, about an hour before sunset. The light was fading a bit, so they got progressively darker despite trying to work fast. This is a 'real-usage' test, no bokeh-testing or wide-open or anything, this is how I use wide angles on MF. All on tripod, all on f/8, 1/350s, 10s-timer-release. All focussed wide open in the middle, and stopped down manually. All are wet-mounted neg scans, Betterscanning holder in v750, Silverfast AI (yes, the colours look different in some, that's the scanner/software not the lens, but this is not a test of colour, I'm looking at sharpness only). Yes, I could probably RA4 print better than these scans, these are only to be compared against each other, not against anything else. Also, these are different focals lengths, so the edge of one is not the edge of the other, obviously (the 50mm is close enough to the 45mms, but the 35mm is a lot wider). I've only cropped one edge, but the other edge is about the same. I didn't bother looking at corners a) because it's all sea and sky here, and b) it generally is when I shoot landscapes anyway so I don't care about far corners. Finally, on the crops, they're huge. 800x600 at 3200dpi scans, on my 27" 2560x1440 monitor is like looking at a 64"x48" print from just over a foot away. Huge. And nothing I'd ever do in real life. But even at 'fit to monitor' (approx 16"x12", which I might print) I can still see which ones are sharper where. Above all, it was a test for me to see which of these I should keep or sell, maybe what to use in which situation, I'm only sharing to see if anyone else might find the results useful. Firstly, the 45mm FOV shot to get your bearings: And the 35mm shot is here but I've done my 10 images so have to link it. The 50mm shot is not that much narrower than the 45mm shot and I'm too lazy to shrink it, so use your imagination. The centre crops: 45mm Sekor: 45mm Takumar: 50mm Flektogon: 35mm Sekor: The edge crops are taken from the very edge of the 50mm frame, so about 5-10% in from the 45mm frame: Sekor 45mm: Takumar 45mm: Flektogon 50mm: Sekor 35mm (where the edge of the others are): Sekor 35mm (the actual edge of the frame): So what's the conslusion? Buggered if I know. What was the question? The Mamiya 45mm is slightly sharper in the centre than the Takumar, but a lot worse at the edges (which makes sense, the Takumar covers 6x7, a 645-edge is no problem for it). The Flektogon, uh, wow? Sharp edge-to-edge, beats the other two overall, but a bit narrower FOV. It's definitely a keeper on my Pentacon Six family, where it's all I've got (besides my other 2 Fleks), but more than useful on the m645 too where I can choose from these others. Out of these three I might sell the 45mm Sekor. For sharp centres I think I'll grab the Flek, for just that bit wider I'll grab the Tak (although the Sekor is smaller, and there's really nothing bad about it, just the other two are better, so maybe it'll find life as a travel lens). The Tak takes 82mm filters and the Flek 86mm, so using 67mm filters is also a plus for the Sekor45. Also, it's f/2.8 where the others are f/4, so in lower-light it's got them beat. But I don't tend to hand-hold nor wide-open MF where I can avoid it, so this advantage doesn't work for me, it might for others. The 35mm Sekor. Hmmm. I've noticed it before on other shots (part of the reason I wanted to do this test, really). On another shot I cropped a 35mm frame to about a 45mm FOV, printed it 8x10, and it still looked dodgy from 2' away. Centre holds its own against the others. But the edges, poor poor edges. Yes it's wider. But what's the point if the extra bits that I get are not good enough to use? It's almost as sharp as the Takumar out to the 45mm-edge, but then it goes wider into mush, so I'd probably only get a usable 45mm-frame out of it anyway. I'm calling this at best a 40mm lens and a bit of cropping. But I don't know if this is just my copy or typical. I've always wanted to pick up another (preferably N or AF version) to see if it's any better, but they're rare and expensive enough that it's not feasible. It almost looks like field-curvature, the way one part of the boat is perfect and the other half starts going downhill, so one day I might test that theory too. (anyone else with a 35mm Sekor feel free to chime in with examples here, nothing would make me happier to know it's my copy and not all of them). Anyway, that was my Sunday morning.