Phase/Mamiya 28mm on full-frame

[Jack]

There have been several questions on the Phase/Mamiya 28mm wide angle lens. When we were testing the S2, I took an opportunity to give my copy of the 28 a difficult run and thought some of you might find the results interesting. This shot is nothing special other than putting the lens through some difficult paces.

First off, the Sun is directly behind the very tip of the building. This was on purpose to test veiling flare, which this lens seemed to be very resistant to. This of course means the sky surrounding the building tip is fully blown, but it also gives you about as high of contrast edge to look for fringing issues as you can get. There are also the branches in the trees on the RH edge crop. Next you'll see the extreme LL corner crop as well as a crop just inside that one, so you can see the progression of sharpness. Next is a crop of the downspout just to show the 2/3rds outer edge of the PoF.

For reference, the focus point was the center frame ladder at f16, so honestly the corners would be even better if I focused closer, but then the more distant tree branches would be worse. (Ideally I would have shot three or four shots here with varying focus distances, but at the time I was really only interested in flare characteristics so didn't think of that at the time.)

Processing was all done in C1. Original exposure was 1/30th at f16, ISO 100. In processing there was no exposure compensation, +10 points Contrast, a 25 point boost to the shadows, 10 points of clarity. Sharpening was my base P65+ sharpening, 140%, 0.8 radius, threshold 2.0. Noise was Lum 0, Color 30. I *did* use the built in lens corrections for the Phase 28mm which included default CA, Purple fringing OFF, Default distortion at 100%, Corner sharpening at 150%, and Default light falloff at 10%. Nothing else was done to the files in post except pulling the crops and converting them to sRGB jpegs in CS, so these are basically crops straight out of C1 after the above adjustments.

Again, not definitive, but I hope you find them helpful.

Full frame with 800 pixel crop areas outlined:



Crops, all should be self explanatory:











All in all, I am very happy with the lens, but my best results are achieved with the lens stopped down and C1 corrections applied. Moreover, for critical results, a bit of crop may be in order depending on the image. However, worst case is it makes a great 30mm .

[Guy Mancuso]

Plus you have corner sharpness in the lens corrections in C1 that really do help a great deal. Nice test Jack as always

[jlm]

jack:

what is your opinion regarding lens sharpness with respect to subject distance? i have found my zeiss 40 to be much crisper focused at longer distances (set at near of at inf.) than at moderately close distances, say 8-20 ft.. I'm not speaking about DOF, but crispness in the plane of focus

[Jack]

Excellent question John.

I see only small differences, but generally find the 28 and 150 seem slightly better at closer focusing distances, yet my 75-150 and 80 prime seem a little better nearer infinity. My 45 seems the same close or far.

[Christopher]

That is a much better copy then I tried. A lot better than all three copies I tried before not buying the lens.

[Guy Mancuso]

I got lucky myself and have a excellent copy of the 28mm even on the P65 back it is really good. Buy with return options just in case, in this case I bought from my dealer. I think the 28mm for sure with a return for another is the right path. Tough lens to build

My one trick with this lens with regards to focus is stay on the close side and let DOF carry the back end

[Guy Mancuso]

Chris give Dave or Steve a call at CI. He will hook you up if you want one

[Jack]

Originally Posted by Christopher

That is a much better copy then I tried. A lot better than all three copies I tried before not buying the lens.

Chris,

My dealer had two on his shelf, and I asked him to test them for me and send me the best one. He did, and at the time claimed they were identical, so he asked me which serial number I preferred . My only point here is perhaps they have tightened up some manufacturing tolerances and now may be generating a higher proportion of good copies? (And mine is a Phase branded lens.) I will also point out that most of the other folks I know that have "good" 28's all claim they work best at f16, and mine is no exception -- f16 is notably better in the extreme corners than f11, though about the same in that second crop in, and FWIW f22 is equally as good as f16.

[dubaiphotography]

I think you are right guys,