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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