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 p.24 #16 · Sigma 45mm f/2.8 DG DN Contemporary Review | |
This is a intriguing lens. Either there is massive copy-to-copy variation, or the characteristics vary considerably according to distance, mount, etc. For example,
* https://www.opticallimits.com/sonyalphaff/1068-sigma45f28fe?start=1 finds "The Sigma lens is already pretty sharp across the frame at f/2.8 albeit it doesn't bite yet. The center does bite - hard - at f/4 and f/5.6 and the outer image region is very good indeed at these settings."
* https://www.camerastuffreview.com/nl/sigma-lenstest/sigma-45mm-f2-8-dg-gn
* https://www.lesnumeriques.com/objectif/sigma-45-mm-f-2-8-dg-dn-contemporary-p53135/test.html finds that "The results obtained after measurement show a very good homogeneity of the lens, with the edges and corners of the image almost equivalent to the centre in sharpness, at all apertures. It's very rare, but not surprising, for Sigma, who had already impressed us on this point with lenses like the 40mm f / 1.4 DG HSM Art. Another highlight of this lens is to offer a quality virtually equivalent at all apertures. In the field it is an important point that allows to choose aperture only for its aesthetic implications for the image and not for the best performance of the lens at a given aperture. This is all the more significant as this 45 mm opens at most only f / 2.8. Finally, the measured sharpness values are excellent. We do not have many comparison points for L-mount lenses on the Panasonic S1R yet, but they easily reach the measurements made with the Panasonic S Pro 50mm F1.4."
* https://www.digitalcameraworld.com/reviews/sigma-45mm-f28-dg-dn-review "Centre-frame sharpness is average with the lens aperture wide open at f/2.8, but as soon as you stop down to f/4 sharpness becomes very respectable and stays so right through to f/11. Corner sharpness is less outstanding, but still acceptable, even wide open."
* https://www.pcmag.com/review/369976/sigma-45mm-f2-8-dg-dn-contemporary finds that "I tested the 45mm F2.8 with the 42MP Sony a7R III and Imatest software. At f/2.8, the pair resolves 3,715 lines on a center-weighted evaluation, a result that is considered very good for the a7R III sensor. The lens captures images with very even resolution from center to edge, an indication fo a flat field of focus and very strong optics.
There's no noticeable change in resolution when shooting at f/4, just an imperceptible drop to 3,654 lines on average. We see a big jump at f/5.6, where the lens hits 4,349 lines, an excellent result. It peaks at f/8 (4,425 lines), and is just as good (for all practical purposes) at f/11 (4,286 lines).
Diffraction sets in at f/16, with resolution dropping to 3,858 lines. It's more of a concern at f/22the resolution drops all the way to 3,027 lines on the a7R III. Even if you aren't using a high-resolution body, diffraction will soften shots at f/22."
Their design is said by Sigma to have the following characteristics:
https://www.sigma-sein.com/en/ohsone/45mm-f2-8-dg-dn-contemporary/
1 The overall MTF performance is lower due to the flares caused by spherical aberrations, but all other aberrations especially color aberrations are wonderfully suppressed, resulting in unexpectedly great MTF performance in high frequencies. In other words, the image is covered by a very thin veil, but its optical resolution is extremely high.
2 The remaining aberrations are spherical in nature, meaning that an aperture stopped down two stops already results in an MTF profile to rival our Art series lenses.
3 With our optical design, the spherical aberrations are low towards the infinity focus and increase towards the minimum focusing distance, so we achieved sharpening the distant view area with few bokeh and making soft and beautiful bokeh at the distant view area where many bokeh occurs.
which translates to the following MTF:
https://www.sigma-global.com/en/lenses/cas/product/contemporary/c019_45_28/data/
ie, uniform, but not record-breaking performance, flat to the edges, but not the corners.
So this seems to be more of a test of the testers, than the lens...
Edited on Oct 05, 2019 at 10:06 AM · View previous versions
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