Pushing the 7.5x Mitu down to 1.8x on MFT

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Lou Jost
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Joined: Fri Sep 04, 2015 7:03 am
Location: Ecuador
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Post by Lou Jost »

I really have no special skills with stacking...I do think that part of our tests should include an actual stack of a difficult subject, to see what effect the CA has on the final stack. After all, at the end of the day, that is what counts. But a uniformly detailed subject like the wafers that Robert uses are much better than a complex subject for testing things like corner-vs-center resolution.

Until I get a wafer, I will try to find a more uniform region of a butterfly wing for my future tests.

As a side note, the road construction that was causing vibrations a few days ago is over, and the road past my house is newly asphalted. Surprisingly, the soft smooth new asphalt is greatly reduced the traffic vibrations relative to the amount I had with the old, pitted, pot-holed asphalt. So there's a new vibration-reduction technique--new asphalt!

Lou Jost
Posts: 5948
Joined: Fri Sep 04, 2015 7:03 am
Location: Ecuador
Contact:

Post by Lou Jost »

I've now tested a few other short lenses with the Mitu 7.5x. I tested a Revuenon 55mm f/1.4 lens (an old cult classic), hoping that the slight extra length relative to the Oly 50mm might fix the corner vignetting. It did, but it still left the corners degraded, in fact worse than the 50mm Oly.

Image

I also tried a Pentax SMC 50mm f/1.4. This did not vignette, unlike the Oly 50mm. Maybe there is something special about Pentax lenses? Sorry for the change of view between tests. About 75% of the horizontal length of the frame was good, and that is much worse than the results with the Oly 50mm, which is good across almost 90% of the frame.

Image

I've also tested the Mitu 10x which does even better than the 7.5x.

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