philip_pj Offline Upload & Sell: On
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Tariq, the discussion and images relate purely to f1.4.
If you look at the f1.4 MTF for each you will notice the greater fall-off of imaging quality in the ZM...by 20mm out, just inside the corner, we see - on Zeiss's own optical bench - just ~30% contrast. Center is ~82%, these are for detail readings off the 40 lpmm line pairs, but echoes are seen in more broad detail lps from around 12mm - the short edges. This is a very large drop and it is a valid result. I would not expect great corners on any Leica camera for this lens at this aperture. But, see the stuff hanging off the trees? Not so good on the ZM, is it? A confusing picture..not much that is off center in the ZM image looks very good to my eyes, when it should be very good.
The FE at same aperture, but with 'optimistic' calculated MTF results, show data going from high 60s at center to an average of around 45% at 20mm out. With a much less severe hit for the 10 and 20 lpmm pairs of lines as well. It's very likely the *shape* of Sony's measurements are faithful and accurate across the frame, if not the level.
My view is that - at f1.4 - the Sony has better (more 'Zeiss-like') shaping and can be expected to show greater consistency from axis to corner, based purely on MTF data. As your eye moves across the frame, the reference point is the sharpest point - the center. It's our visual system at work and it may contribute to the appearance of the images posted. [As an aside, such a flat profile occurs very often in lenses with outstanding bokeh - 50AA, Otuses, all good teles).]
I don't say it is the only factor at play; it's hard to find exit pupil distances from Zeiss's latest charts and we don't even know its max beam angle; it was not a lens intended for the Sony system; nor have I seen any comparable f8 MTF data. CZ only publish 'best overall' aperture data in their charts (f4 here), it may be that the ZM tanks early, it can and does happen. [Sony publish f8, come what may.] Maybe LC has covered some of this, I don't subscribe. It's doubtful either of these are great shakes at f8, it's far from their intended purpose.
These are unpopular messages, I realise that, we all want the ZM lenses to work well. If the center is very sharp on the ZM, a tripod is not needed for 'same image' analysis, deterioration will affect all of the image. If it shows up in successive images the case is strengthened. But yes, a pod eliminates more grey area, when digging deeper.
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