Chris,
I think my statement caused some confusion. It was poorly crafted, to say
the least.
The lens that I referred to is a Leica-R Summicron 50/2, and must use a
Leica-R to 4/3 adapter, so it won't work with the M42 adapter. What I found
with this lens is that the most distant object I can find comes into focus
before the focusing index reaches the infinity mark. I have to back off
from the infinity stop to get it in focus. This is the lens I used to see
what an "infinity" image would resolve with my camera.
I compared the previous image, made with a Pentax Takumar 55/1.8 lens and my
M42 adapter, to the Summicron image, and, at a distance, I find little
difference. As Chuck pointed out, it appears that the earlier image was
made at a smaller aperture, because the foreground was sharper.
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Chris Trask" <christrask@xxxxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Monday, August 22, 2011 2:58 PM
Subject: Re: [OM] Was: mount mod; Now M42-to-4/3 Adapter Thickness
> >
>> It had been a rough morning, Chuck, and I just didn't write it down. My
>> point is, that I would seldom use a large aperture when shooting at
>> infinity, so the technical point about the thickness of the adapter is
> more
>> academic than useful.
>>
>> I appreciate your concern for the details, but I think I will let this
>> one
>> slide by. Thanks.
>>
>
> Whoa, don't do that. When I did my OOF test earlier I had the aperture
> set to f/22, so I suspect now that if I had opened it up to f/6.8 I would
> have seen OOF objects even closer. I will keep that in mind when I redo
> that test after the thin M42/OM adapter arrives.
>
> But now I have an additional question: You said earlier that the one
> lens you used would focus beyond infinity. Do you still have that excess
> focusing available with the M42/OM adapter, or are you now just short of
> it?
> If you had sufficient excess focusing travel on the lens, that would
> explain
> why you are able to obtain infinity focusing with the thicker adapter.
>
> The 400mm f/6.8 lens I've been testing has no focusing beyond the
> infinity mark, so any adverse thickness in the adapter would prevent me
> from
> focusing at infinity.
>
> Chris
>
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