Exactly. I wanted to eliminate the DOF effect, so I started with f/1.8.
That one, to me, is too soft to really see the distant objects. As far as I
can see, the others are in focus to the furtherest object I can see in the
image.
Incidentally, I started with a 7mm spacer, and the index at the top. I
ended up with the index at about 45 degrees, which is 1/8 of the 1mm thread
pitch. Hence, 7.000 -0.125 = 6.875, the distance that you specified.
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Monday, August 22, 2011 9:58 PM
Subject: Re: [OM] Was: mount mod; Now M42-to-4/3 Adapter Thickness
> Sorry, I think I've lost track of the purpose of these photos. I
> thought that with the reworking of the adapter you were attempting to
> see if you had infinity focus. Is that what these images are showing?
>
> Chuck Norcutt
>
>
> On 8/22/2011 8:12 PM, Jim Nichols wrote:
>> Chuck,
>>
>> I started with a sheet of 80 grit laid flat on the top of my table saw,
>> then
>> finished up with 400 grit. The result is an adapter that is
>> approximately
>> 6.9mm in thickness. The only down side is that the lens screwed into the
>> adapter approximately 45deg further than before, so the lens index,
>> formerly
>> at the top, is now down on the left side. No big deal.
>>
>> Here are some representative photos, with f stops. Just as a reminder,
>> you
>> can't use exact f stops in a title. I had to use dashes instead of
>> periods.
>>
>> Although I shot at all marked stops, from 1.8 to 22, I only posted four
>> images as examples. The sun was getting lower as the f stops got higher,
>> so
>> the light does change somewhat.
>> http://gallery.leica-users.org/v/OldNick/Takumar+55+at+f1-8.jpg.html
>>
>> http://gallery.leica-users.org/v/OldNick/Takumar+55+at+f2-8.jpg.html
>>
>> http://gallery.leica-users.org/v/OldNick/Takumar+55+at+f5-6.jpg.html
>>
>> http://gallery.leica-users.org/v/OldNick/Takumar+55+at+f11.jpg.html
>>
>> Except for the softness of the lens at f/1.8, I think all of the images
>> are
>> acceptable. f/5.6 appears to be the best.
>>
>> Comments welcomed.
>>
>> Jim Nichols
>> Tullahoma, TN USA
>> ----- Original Message -----
>> From: "Chuck Norcutt"<chucknorcutt@xxxxxxxxxxxxxxxx>
>> To: "Olympus Camera Discussion"<olympus@xxxxxxxxxxxxxxxxx>
>> Sent: Monday, August 22, 2011 6:26 PM
>> Subject: Re: [OM] Was: mount mod; Now M42-to-4/3 Adapter Thickness
>>
>>
>>> What's this? A metal turning lathe in the basement?
>>>
>>> Chuck Norcutt
>>>
>>>
>>> On 8/22/2011 5:52 PM, Jim Nichols wrote:
>>>> I just thinned my M42 down to 6.9mm, to agree with Chuck's specs. I
>>>> will
>>>> give it another try when I have time.
>>>>
>>>> Jim Nichols
>>>> Tullahoma, TN USA
>>>> ----- Original Message -----
>>>> From: "Chris Trask"<christrask@xxxxxxxxxxxxx>
>>>> To: "Olympus Camera Discussion"<olympus@xxxxxxxxxxxxxxxxx>
>>>> Sent: Monday, August 22, 2011 4:01 PM
>>>> Subject: Re: [OM] Was: mount mod; Now M42-to-4/3 Adapter Thickness
>>>>
>>>>
>>>>>>
>>>>>> 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.
>>>>>>
>>>>>
>>>>> Okay, now I better understand. To rephrase what I stated
>>>>> earlier,
>>>>> I'll
>>>>> have to keep in mind to open up the aperture fully so as to reduce the
>>>>> depth
>>>>> of field when doing the focusing test later. That adapter is on a
>>>>> slow
>>>>> boat
>>>>> from Calcutta, so it's going to take a couple of weeks before it
>>>>> arrives.
>>>>>
>>>>> Chris
>>>>>
>>>>> --
>>>>> _________________________________________________________________
>>>>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>>>>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>>>>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>>>>
>>>>>
>>>>
>>>>
>>> --
>>> _________________________________________________________________
>>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>>
>>>
>>
>>
> --
> _________________________________________________________________
> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
> Themed Olympus Photo Exhibition: http://www.tope.nl/
>
>
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