>Well, let me make myself a bit more clear. I don't regard pinhole as
>being "hit and miss" at all; that's not really what I said (I hope the
>quote marks weren't quoting me!).
My apologies, I was using the quotations as standard phrase markers, not to
imply they were your words. My mother, before she retired, was a high
school English teacher. She wouldn't be happy with me! In reading your
complete post, I feel I've angered you. If so please realize it wasn't
intentional.
As to my use of the term (hit and miss), I would suggest that all
photography is hit and miss. Otherwise why do we all have soooooooo many
negatives we never print and/or show? Pinhole seems to me to be even more
hit and miss. In most cases we can not aim and/or compose as well as we
can with lens cameras. Neither viewing pinholes nor frame guides (a few
nail heads used to line up the field) are very effective. The length of
time a pinhole needs for exposure adds another uncontrolled factor (what
will the subject do during that time).
I don't see this as a negative. Adding a little anarchy and surprise to
photography is part of pinhole's appeal to me.
>If you think that I am advocating an
>attitude of imprecision when approaching pinhole photography, I think you
>misunderstand me pretty seriously. What I do mean is that there is a
>very broad continuum between the art and the science, and the
>interpretation (art) is at least as important as the calculation
>(science). I calculate my holes carefully, too. But the application of
>the specific pinhole really may be more important than the particular
>number you may happen to believe in.
I agree, and mentioned in my post that I too often use a size that doesn't
fit the standard equation, because it will give me look I'm trying to
achieve. The original post was about a beginner trying to build his/her
first camera and wanting to check a basic formula.
>Actually, I did a series of practical tests for a studio in NY some years
>back, shooting polaroids of newspaper text with various carefully made
>holes. I began with the formula I got from the _Photo Lab Index_ which
>was d=sqrt(.00007f), where d is the diameter of the hole and f is the
>distance of the hole to film (my own rewording of this formula). This
>may be similar to what you have; I'm not going to calculate it out for mm
>- if you care enough about it, you can do that yourself. What I found
>was surprising. The smaller the hole, the better the resolution, as far
>as I went, and I got the factor represented in the formula by the .00007
>down well below .00005.<SNIP>
I believe that everyone is coming up with very similar equations, simply
stated differently. In previous posts I used a 3 inch or 75mm focal length
as an example. My equation gave 0.31mm, reverse figuring Eric Renner's
gave me 0.32mm, your two equations give me 0.37mm or 0.31mm These are all
so close, that compared to the quality of the hole and it's application, I
don't see any reason for us to disagree. The original posters equation
would give 0.2mm. That is far enough off standard that I thought it worth
commenting on.
>BIG SNIP<
tomf2468@pipeline.com (Tom Ferguson)