Re: [OM] The KEH upgrade

Subject: Re: [OM] The KEH upgrade
From: Moose <olymoose@xxxxxxxxx>
Date: Tue, 12 May 2020 16:09:50 -0700
On 5/12/2020 3:31 PM, Ken Norton wrote:
My KEH used (EX)  $9.78 USD Fotodiox OM-NEX adapter arrived today. I'm
not sure what form of human error occurred, but I'm not complaining. I
received a flawless NOVOFLEX OM-NEX adapter instead.

Checking infinity focus, there is definitely a focus shift as it's
probably a solid 1mm too short, but I'd much rather have it this way
than too long.

Put the Novoflex on the 'Bay and buy a Fotasy that's the correct length. I won't put up with an adapter that doesn't reach infinity focus at the mechanical lens stop. Just too damn inconvenient. And- you make a profit!

Other than the fully-expected corner vignetting caused by the
too-narrow lens-mount on the SONY, the lenses are performing as

Huh? I've not noticed that. The mount isn't much narrower, ~43.5 mm vs. ~47 mm. And the mount is much closer, ~28 mm, to the sensor so the cone of light narrowing towards the focus plane should be quite a bit narrower than at the OM register distance.

Looking at pix of the Novoflex on their site and B&H, it appears that the inner tube is the same diameter as the exit opening - all the way up to the OM mount. It narrows immediately, at the widest point of the cone of imaging light. The Fotasy I have drops away to much wider right behind the OM mount. It's possible that the Novoflex tube is acting as a baffle. Just because it's German, and expensive, doesn't mean there couldn't be a (second) design mistake.

Speaking of which, I'm pleased to report that the OMZ 300/4.5 performs
much better on the SONY, as it did on the Canon 6D than it does on the
4/3 and m43 cameras. The sensor stack of the Olympus/Panasonic digital
cameras is generally underperforming with this specific lens.

As well as using only ~1/4 of the image circle used on FF. Or are you comparing equal crops? I thought sensor stack thickness becomes less of a problem as FL increases. (Geometry again, incident angle of rays of light to the stack.)

Geometry Joe Moose

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