Re: Close-up lens depth of field

[P3D Eric Drysdale <edrys@xxxxxxxxxxxxxxxxx>]

Hello everyone...

Jon Orovitz writes, re my close-up question:

>I'll bet John B. can produce the formula!

It would be great if he could.  On Dr. T's advice, I used a ground glass
(scotch tape) to determine my d.o.f. at the smallest aperture that I could
still see clearly, and marked that distance off on a cloth tape measure.
(I'll do this again when I actually take some pictures) It would be nice to
have a formula, however, to back up what I see.

>, I
>find that a standard Stereo Realist completely runs out of steam close
>to 1.5 feet mark.  At that distance (46cm), your stereo base is still
>7cm, giving a (min. distance:stereo base)ratio of about 6.5:1.

I'm one step ahead of you, and have rigged up a makeshift macro bar using a
twin slr bar that Greg Dinkins lent me with an adhesive ruler on it, kinda
like what the stereolusions section of the Realist manual shows.
Unfortunately, I got interested in photography through stereo and don't
have (and never had) an SLR.  I could have used a friends, but I found a
full set of ser. V diopters (+1,2,3, and 6) at a camera show for 5 dollars,
where a 52mm lens would have cost me plenty more, with less experimental
value.  My  realist probably has better lenses than a modern slr anyway,
right?

For those who are following the story of my misfocusing Realist, I think it
seems fine, though slightly less sharp and contrasty than the Ilex one.  I
set it on a tripod outside where there happened to be a row of about 20
trashcans, so I focused on the near, middle, and far, at 3.5. (somehow I
forgot- duh- to try infinity, which is why I only think it seems fine- I'll
do one more test to be sure)  I'm probably just not holding it still
enough.  Live and learn.

For those in the NY area, you should know that I used Duggal's overnight
Kodachrome service.  What they say is true.  In by 5:30 pick up 10:am next
day. I don't think it's one of these newfangled machines, I think they just
have someone shuttle it back to New Jersey... now I have no excuse not to
shoot kodachrome.  Price, maybe.

Thanks for your input Jon, I'll let everyone know how it goes... once I
figure out what to take a close-up _of_!

-E

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-   Eric Drysdale         Jews of the '50s in 3D      -
-         mailto:edrys@xxxxxxxxxxxxxxxxx              -
-  http://www.users.interport.net/~edrys/jews.html    -
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