P3D Re: Macros and Hypo

[Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Fri, 5 Dec 97
>From: John Bercovitz writes:
>.................
>
>>Larry B writes:
>
>> I agree with both you and Dr. T. However, I'll point out that for
>> Macros done at a distance of 12 inches or less from the lenses, the
>> resulting images wouldn't even have the same subject matter in them unless
>> you were technically set up to take a HYPO
picture.............................
>
>I don't think I've done shots at 12" with a normal base but I have done
>some at 40" with a 190 mm base .......  Maybe I should do a quick calc...
>
>Yes, with 50 mm lenses, 24x36 standard SLR frame, and 67 mm sterobase, if 
>you use standard 5P mounts (21.5 width), you will get full coverage at 231
>mm distance which is about 9".  Would a sketch help?  I could make a GIF.
>If you use a 35 mm lens on your SLR, one would be able to get closer, but
>I personally don't have a viewer to match that focal length.
>

****  Your figures work for me. However, I determine by your figures that
the camera I've been using at 12" doesn't have the lens lengths you used. So
my illustration would be better if I had stated some distance figure like
less than 6 inches.

The camera I've been using at 12 inches is labeled 11mm and F2.8. It has a
standard setting (focus at 4' to infinity) and a Macro setting (focus at 12"
). There is nothing to tell me what figures apply to the Macro situation.

I think that if one wants a good stereo image from a distance of 12 inches,
it is best to reduce the stereo base, even if you could fill a 5p frame with
the results. The convergence angle or ratio of base to distance would be a
bit extreme. :-) That's a 1:5.3 ratio aprox. instead of a more ideal 1:15 or
the realist slide ideal situation of 1:30.

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


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