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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