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Re: [OM] The KEH upgrade

Subject: Re: [OM] The KEH upgrade
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Tue, 12 May 2020 15:49:37 -0800
> AHA! Compare vignetting.
> Holding My Breath Moose

No need to worry. The vignetting I'm seeing is specifically related to
the protruding lens mount into the corners. It's something I see
referenced all over the Interwebs regarding the SONY Alpha series. I
expected to see it and when I go looking for it, I can find it. The
other brands have a larger throat. Also, I've noticed a little corner
darkening related to sensor offset, but this is with the native lens
too. Regardless, it's not a big enough of an issue for me to worry
about at all. I almost always do a little cropping of my images
(usually because I have to level the image) and if I think in terms of
35mm film, I was rarely able to use 100% of the image area either.

The other optical vignetting with the OMZ lenses is certainly
prevalent with some of the lenses, but is either easily addressed in
the computer or eliminated by stopping down a couple of stops. The
wide-angle lenses certainly have a lot of vignetting wide-open, but it
gives the images character too. :)

As to the 300/4.5, I've found that this lens underperforms on the
crop-sensor cameras from what I can only surmise is an overly
"telecentric" lens, such as a super-telephoto where the exit glass is
so far from the film-plane, has the image compromised by the sensor's
microlenses that are designed for less telecentricity.

The 300/4.5 could give me exceptionally sharp images on the 6D and I
can see that it's doing the same on the SONY.

More to come.

A7 Schnozz
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