MTF test results for the Olympus 45mm f/1.8

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NetworkMan New Member • Posts: 16
MTF test results for the Olympus 45mm f/1.8

Lensrentals have reported some MTF tests for the Olympus 45mm f/1.8 lens that show a lower edge resolution at f/2.8 than they do at f/1.8.

https://www.lensrentals.com/blog/2018/03/finally-some-more-m43-mtf-testing-are-the-40s-fabulous/

This rather strange behaviour is ascribed to pronounced field curvature but I have not seen it mentioned in any other test reports or reviews.

If you look at the test on lenstip:-

https://www.lenstip.com/316.4-Lens_review-Olympus_M.Zuiko_Digital_45_mm_f_1.8_Image_resolution.html

... you can see that the edge resolution at f/2.8 is better that that at f/1.8 as I'd expect and indeed if you look at the review of the newer Panasonic 42.5mm f/1.7 you can see that the two lenses are very similar with the Panasonic just a little better.

The behaviour of the Olympus is confirmed on the Imaging Resource Website:-

https://www.imaging-resource.com/lenses/olympus/45mm-f1.8-ed-m.zuiko-digital/review/

... which uses a rather good graphic using colour to show resolution over the whole field with a slider to change aperture.

I'm at a loss to explain the lens rentals result.  Can anyone help?  Remember we are not just looking for edges less sharp than the centre, we are looking for edges becoming less sharp as the lens is stopped down a small amount (before diffraction sets in).

Hoping for some light to be shed and thanks in advance!

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