Thanks, Chuck. I try to put up a few, when my wife will allow it.
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Sunday, December 21, 2008 7:50 PM
Subject: Re: [OM] 420 deal, Now Back Focus/ Front Focus
> Ooops! I meant to add... nice portraits on that page!
>
> Chuck Norcutt
>
> Chuck Norcutt wrote:
>> 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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