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Re: [OM] Zuiko manual lens options for Sony A7

Subject: Re: [OM] Zuiko manual lens options for Sony A7
From: Jim Nichols <jhnichols@xxxxxxxxxxxxx>
Date: Sun, 11 Aug 2019 15:04:16 -0500
Frank,

From experiments, I found that about the thickness of a sheet of paper can make a difference.  My advice is polish a little, clean, reassemble, check, repeat.  I used a tree at about 300 ft as a test subject.

Jim Nichols
Tullahoma, TN USA

On 8/11/2019 1:59 PM, Frank wrote:
Jim,

thanks for your advice. Now I wonder how long you should move it until you
get some meaningful reduction in length?
As I understand it could be much less then a mm, but still.

My lens turbo works OK ish with lenses of 50mm and longer, but doesn't get
to infinity with shorter lenses.


Frank


Op zo 11 aug. 2019 om 17:27 schreef Jim Nichols <jhnichols@xxxxxxxxxxxxx>:

Frank,

Keeping the surface flat is not a big problem if you use thin emery
paper and wrap it around a sheet of steel or aluminum, lay it on a flat
table, and move the adapter part across the flat abrasive material.

Jim Nichols
Tullahoma, TN USA

On 8/11/2019 9:54 AM, Frank wrote:
With these adapters, usually the bayonet fitting part (at the lens side)
is
a separate chrome plated part attached with screws on the black tube.

I guess you can sand the black tube a bit and reattach the chrome plated
part. However, keeping it perfectly flat could be a challange?

Hmm..  now that I think about it, I have a slightly too long Lens Turbo
adapter myself which I could fix that way, maybe. Would the distance
between Lens Turbo elements and the sensor be less critical compared to
the
elemens and the lens? Does anyone knows?


*Frank *


Op zo 11 aug. 2019 om 16:13 schreef Jim Nichols <jhnichols@xxxxxxxxxxxxx
:

Brian,

I ran into a situation like that with one of my first adapters, where
the adapter was just too thick to allow me to get to infinity.  This was
a threaded adapter, and I simply polished the surface with emery paper
on a flat surface until I got it right.

Won't work with a bayonet mount, though.

Jim Nichols
Tullahoma, TN USA

On 8/11/2019 5:13 AM, Maggie wrote:
Hello all, Brian Swale here.
I've been trying various OM Zuiko lenses on my "new" A7, and the
results are rather mixed.
Firstly, I have come to the conclusion that the nice lens adapter I
bought has one significant secret flaw - it seems to 'not quite' allow
lenses to focus to infinity. Where I am shooting tests from ( our
bedroom balcony) in the distance at about 5 km (3 +- miles) are large
hills, and all the way back to the camera are intermediate targets.

So, using the hot-focus indicator in the screen, those hills show as
being out of focus and the detail of the downloaded images also shows
that. So I need to buy another which is a pity as the build of the
adapter I have is otherwise very nice.

Secondly, indications seem to be that only prime lenses will give a
sharp image. The 50/1.8 and the 100/2 are excellent. The jury is still
out on the others - I will try new tests with the camera on tripod
this coming week. I had thought that the 35-7-/3.6 excellent film zoom
would make a great versatile walk-around lens, but so far the images
disappoint. Similar for the 35-80 and the 35-105. The 75-150
disappointed. The 21, 24, 28, 40 and 85 need re-testing and I haven't
got to the 135 and 200 ( and larger) yet.

We are still in winter with fresh snow on the hills to give some
contrasty details.

Cheers, and back to lurk mode.  Brian

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