Chuck,
I also participate in the LUG, and have heard the stories of cameras sent
back to Solms because of small quirks. I'm happy to use my Oly as it is.
:-)
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Sunday, December 21, 2008 7:47 PM
Subject: Re: [OM] 420 deal, Now Back Focus/ Front Focus
> It's interesting that the focus confirmation chip backfocuses as well
> but I suppose that's as it should be using the same circuitry. Do you
> think you'll send it for calibration?
>
> Chuck Norcutt
>
> Jim Nichols wrote:
>> I followed up with my own crude tests of autofocus accuracy this
>> afternoon.
>>
>> Case 1: Tripod mounted Oly E-510 with Zuiko 14-54 lens at 54mm, aperture
>> at
>> 3.5, using an "X" marked on public notices in the local paper. Camera
>> was
>> mounted at approximately 45deg to the paper. I see about 4 "lines" of
>> back
>> focus in this image.
>> http://gallery.leica-users.org/v/OldNick/Auto+Lens_+Auto+Focus.jpg.html
>>
>> Case 2: Same setup using a Takumar 55mm f/1.8 manual focus lens at f/1.8
>> to
>> get shallow DOF. Lens was mounted with an adapter having a
>> focus-confirmation chip. Focusing was done using the focus confirmation
>> spot in the viewfinder. I see about 2 lines of back focus in this image.
>> http://gallery.leica-users.org/v/OldNick/Manual+Lens_+Manual+Focus+Dot.jpg.html
>>
>> Case 3: Same setup except focus was accomplished using a full screen
>> "Live
>> View" image on the rear screen. I did not use a magnified view. I see
>> about 1 line of front focus, or none at all, in this image.
>> http://gallery.leica-users.org/v/OldNick/Manual+Lens_+Screen+Focus.jpg.html
>>
>> Take it for what it is worth. I have had no complaints with the
>> autofocus
>> combination of my camera and lens. I had been suspicious of the focus
>> confirmation chip, but it seems to work. Live View is just too tedius to
>> deal with.
>>
>> I prefer the Zuiko for sharpness over the Takumar lenses that I have, but
>> the 55/1.8 Takumar makes a fine portrait lens.
>>
>> Jim Nichols
>> Tullahoma, TN USA
>> ----- Original Message -----
>> From: "Jim Nichols" <jhnichols@xxxxxxxxxxxxx>
>> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
>> Sent: Sunday, December 21, 2008 2:51 PM
>> Subject: Re: [OM] 420 deal
>>
>>
>>> Yea, Chuck, I concluded that a tripod might help. Since the previous
>>> example was hand-held, I thought I would give it a try. When I get a
>>> chance, I will try to do that. Incidentally, your analysis is not too
>>> far
>>> off the actual case.
>>> With an f/3.5 lens such as this, it is difficult to be conclusive about
>>> the
>>> actual focus. A faster, prime lens, with AF would be a better example.
>>> Unfortunately, I don't have such a lens.
>>>
>>> Jim Nichols
>>> Tullahoma, TN USA
>>> ----- Original Message -----
>>> From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
>>> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
>>> Sent: Sunday, December 21, 2008 2:37 PM
>>> Subject: Re: [OM] 420 deal
>>>
>>>
>>>> I think I'd put the center of focus on "mittee will study whether to
>>>> demolish" or on the line above. That's based on comparing the blur of
>>>> the descender on the "y" in "money" and the "g" in "bridges" near the
>>>> top with the descender on the "g" in "CBS Evening News" below. I'm
>>>> guessing that you were shooting from about 2 feet and at these close
>>>> distances DOF is pretty much evenly distributed between front and back
>>>> of the central point of focus.
>>>>
>>>> Assuming that the newsprint is spaced about 7 lines/inch I make the
>>>> distance between intended and actual focus about 1-1/4 inches or
>>>> roughly
>>>> 32mm. However, since you presumably had the paper at a 45 degree angle
>>>> laying back from the camera the actual backfocus would need to be
>>>> corrected by the sin of 45 degrees. Roughly 0.7x32mm = 22mm. So I
>>>> make
>>>> it only about half what you estimated. But if you're shooting from two
>>>> feet as I guessed that's still a large error.
>>>>
>>>> But shooting hand held it's probably not hard to bob back and forth by
>>>> 22mm. Maybe you should shoot on a tripod. :-)
>>>>
>>>> Chuck Norcutt
>>>>
>>>>
>>>> Jim Nichols wrote:
>>>>> Frank,
>>>>>
>>>>> I just did my own similar test, though not as professionally, on my
>>>>> Oly
>>>>> E-510 and Zuiko 14-54 lens. With the lens at 54mm, hand-held at 1/180
>>>>> at
>>>>> f/3.5, ISO 400, kitchen lights, I focused on the word "Ascend" in the
>>>>> newspaper caption. The sharpest focus appears to be near the top of
>>>>> the
>>>>> paragraph above the caption, indicating a back focus of about 38-40mm.
>>>>> I
>>>>> made several shots, with this being the better one, but all indicated
>>>>> a
>>>>> similar back focus.
>>>>>
>>>>> The focus dot was on each time I made a photo. While this error is
>>>>> not
>>>>> of
>>>>> much consequence, it was interesting that it consistantly occurred.
>>>>>
>>>>> http://gallery.leica-users.org/v/OldNick/Focus+Test.tif.html
>>>>>
>>>>> Jim Nichols
>>>>> Tullahoma, TN USA
>>>>> ----- Original Message -----
>>>>> From: "Frank van Lindert" <Frank@xxxxxxxxxxxxx>
>>>>> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
>>>>> Sent: Sunday, December 21, 2008 10:45 AM
>>>>> Subject: Re: [OM] 420 deal
>>>>>
>>>>>
>>>>>> This is one of my tests, reproduced today.
>>>>>> http://home.tiscali.nl/vanlindert/Calibration_E-400/test_diepte/test_diepte1.JPG
>>>>>> I focused on the line indicated by the blue marker.
>>>>>>
>>>>>> Frank.
>>>>>>
>>>>>> Sun, 21 Dec 2008 17:22:04 +0100, Frank van Lindert
>>>>>> <Frank@xxxxxxxxxxxxx> wrote:
>>>>>>
>>>>>>> I first had a setup like yours, taking pictures along a ruler. And
>>>>>>> yes, it was all macro with the 14-42/3.5-4.6 standard zoom lens
>>>>>>> which
>>>>>>> was part of the E-400 kit.
>>>>>>>
>>>>>>> Later I have learned that it was better to photograph plain
>>>>>>> newspaper
>>>>>>> print from an angle which is about twenty degrees from horizontal.
>>>>>>> It
>>>>>>> will give you a better feeling of the depth of field, which was my
>>>>>>> primary concern when testing different lenses and macro converters.
>>>>>>>
>>>>>>> BTW, my favorite macro converter is a lens which I unscrewed from an
>>>>>>> Olympus slide copier (intended for copying slides or negatives to
>>>>>>> digital). Its thread being 58mm it screws right onto my 14-42. Its
>>>>>>> focal length is about 10cm.
>>>>>>>
>>>>>>> Frank.
>>>>>> --
>>>>>> _________________________________________________________________
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>>>>>>
>>>>>>
>>>>>
>>>> --
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>>>>
>>>
>>> --
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>>>
>>
>>
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