Just to make the point I have two "Zeiss" lenses marked with T* and dual serial numbers. They are made by Sony. So I'm not Zeiss sceptic.
You are also right that sharpening is part of the mix. A lens having benign aberrations would sharpen better than one having extreme corrections.
I also checked out the Diglloyd article and his finding was in part the reason I posted the question. He essentially says that the lens is lacking contrast and needs to be stopped down to f/11, but when stopped down it draws lovely. Diglloyd says that it is only matched by the 100/2 Macro Planar. I mostly shoot at f/8 so F/11 is OK with me.
A couple issues where I don't agree, but I am open for good explanations:
1) Flatness of field. When I shoot landscape, more often than not everything is at infinity. Curvature of field would affect edges and corners negatively: I would claim that a landscape subject at infinity when rendered in the focal plane would be flat. So I would argue that low curvature of field is important.
2) To my knowledge diffraction is only dependent on lens opening. Now, the shape of the aperture matters but most modern lenses I have nearly circular aperture. Diffraction is a property of light and nothing lens designers can do about. The reason that lenses loose sharpness is diffraction. The earlier a lens is becoming diffraction limited the better is the lens.
Now, I may be wrong on these issues. You can perhaps explain where I err, or point me to some source of information? Life is a learning experience!
I don't understand your statement "and a much denser blue channel (about 15-20%) gives the Zeiss glass this 3D look." Which blue channel are you talking about?
Also, could you post a sample with an example of "this 3D look", perhaps also with another image lacking the 3D look. It is much talked about, but I have not seen it demonstrated. Well possible that my Zeiss lenses have some of that 3D-look, I don't know.
Thanks for responding and trying to enlighten me about the issue.
the Zeiss MF lenses that we use are somehow misrepresented by the shere numbers. If you read Lloyds test he also states this.
it is my experience that many lenses, especially from the MF range are totally misunderstood and should be looked at new from a digital point of view.
First- a larger imagecircle and the longer Flange Focal Distance result in chromafree and very low vignetting images. This kind of uniformity
is much more important than what people see in these MTF charts, which are valid only for flat repro situations which are not occuring in 99% of all images shot.
A final sharpening of very uniform and clean but not so sharp image will result in a better image than a pinsharp center with a lightfalloff with chromas in the edges and
uneven image character.
I see this proofed by many of our customer Photos who are more and more realizing that the current mainstream of lens"knowhow" totally misrepresents
the fact that some older lenses are also not so much prone to diffraction (many new lenses have their peak at open aperture which makes them nearly unusable
if you NEED to stop them down e.g. for product Photography where you just need this depth of field and struggle for every mm !)
This in combination with the special T* coating (7 layer-still best of all!) and a much denser blue channel (about 15-20%) gives the Zeiss glass this 3D look.
greetings from Germany