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+--- Thread: Sigma 35mm f/1.4 DG DN ART announced (/showthread.php?tid=5037)
Sigma 35mm f/1.4 DG DN ART announced - Klaus - 04-27-2021
https://www.sigma-global.com/en/lenses/a021_35_14/
E- & L-mount as usual.
RE: Sigma 35mm f/1.4 DG DN ART announced - borisbg - 04-28-2021
Klaus, you usually comment on MTF charts. Don't they suggest uncorrected enough of coma?
Given their 85mm 1.4 DN I was expecting something lighter.
RE: Sigma 35mm f/1.4 DG DN ART announced - Brightcolours - 04-28-2021
(04-28-2021, 02:01 AM)borisbg Wrote: Klaus, you usually comment on MTF charts. Don't they suggest uncorrected enough of coma?
No?
RE: Sigma 35mm f/1.4 DG DN ART announced - Klaus - 04-28-2021
The delta between the solid and dotted curves at 30 lp/mm is fairly marginal so astigmatism is quite low.
Astigmatism = whether the rays of the sagittal plane are focused at a different point than light rays in the tangential plane. If the curves don't match, you will see a line instead of a point (center to corner direction)
Coma = rays don't focus in a point on the plane resulting in a comet-like form.
I haven't thought about coma too much so far but the corner MTFs are high so I'd conclude that the coma is low.