MTF comparison - Zeiss 55 f1.8 for Sony A7R vs Zeiss 55 f1.4 Otus

[Paul Ozzello]

The MTF curves for the the new Sonnar 55 F1.8 FE ZA look incredible and even better that the new Zeiss Otus 55 f1.4. Even though the values are for different f-stops I assume the f4 vs. f8 measurements take into account the lens' optimal aperture (both sets of MTF are measuring 10/20/40 line pairs/mm). Is there something I'm missing ?

The Sonnar 35mm/55mm alpha A7R combination should incredible !

MTF Otus 55 f1.4
MTF Sonnar 55 f1.8

[Manoli]

The MTF curves for the the new Sonnar 55 F1.8 FE ZA look incredible

Are these curves measured or calculated ?

[Paul Ozzello]

Are these curves measured or calculated ?

I don't know, I took them from the manufacturers' websites.

[ErikKaffehr]

Hi,

The Zeiss Otus curves are in all probability mesaured. The Sonnar curves are calculated or designed by the marketing department.

If any curve is close to 100 percent it is calculated as diffraction is not taken into account. For 20 lp/mm I guess that 90% (0.9) is about maximum possible. So I think the Sonnar curves are grossly misleading.

My take on it... but even if Sony is cheating, which I think they do, the lenses could be quite good.

Best regards
Erik

The MTF curves for the the new Sonnar 55 F1.8 FE ZA look incredible and even better that the new Zeiss Otus 55 f1.4. Even though the values are for different f-stops I assume the f4 vs. f8 measurements take into account the lens' optimal aperture (both sets of MTF are measuring 10/20/40 line pairs/mm). Is there something I'm missing ?

The Sonnar 35mm/55mm alpha A7R combination should incredible !

MTF Otus 55 f1.4
MTF Sonnar 55 f1.8

[kers]

...
The Sonnar curves are ....designed by the marketing department....
Erik

that is what i call a good design

[ErikKaffehr]

Hi,

Below there are corresponding curves for the Planar 50/1.4 ZA from Sony info and data measured at Hasselblad on Hasselblads equipment. Note that is a different lens!

Blue curve:  20 lp/mm at f/8
Red curve:   20 lp/mm at f/1.4

Compare these with the green lines.

What I see is that the measured data for f/1.4 is quite similar but the data at f/8 is much higher in the Sony chart.

The corresponding line in the Otus graphs is between 80% and 90% mostly at f/1.4. Much better at full aperture!

Best regards
Erik

The MTF curves for the the new Sonnar 55 F1.8 FE ZA look incredible and even better that the new Zeiss Otus 55 f1.4. Even though the values are for different f-stops I assume the f4 vs. f8 measurements take into account the lens' optimal aperture (both sets of MTF are measuring 10/20/40 line pairs/mm). Is there something I'm missing ?

The Sonnar 35mm/55mm alpha A7R combination should incredible !

MTF Otus 55 f1.4
MTF Sonnar 55 f1.8