Re: pinholes and film speed

Guillermo wrote:

> Shannon,
> Numerically, an EI of 1000 may seem as a big jump from
ISO-400,
> but it is really just 1 1/3 stops faster,

Oh. Hey, you're right!

 which probably can be accounted by a
> combination of factors like: "how thin you want the negatives low zones to
be",
> a bit of anomalies in the reciprocity correction (I am not saying your method
is
> incorrect) and the pinhole actual diameter being a bit bigger than what you
> think it is.

I got this camera from Eric Renner, so I assumed it was "precision drilled,"
whereas nobody knows what size the pinholes I make with a sewing needle
actually are.

As for my shadow areas, I aim for around .35 density.

   Beside the above, 400 is the ISO speed of HP5 when processed as
> per the ISO standards, but it could prove to be a bit faster with your
specific
> processing. An small contribution from all or several of the mentioned
factors
> could easily make your 400 film appear to be 1000 film, instead.

Yes, I have to increase development time for cyanotype, but I do this for
Tri X when I shoot it in my 4x5 camera, and it seems to be about what it is
rated at: 320.

So, I guess it doesn't really matter WHY this is so, as long as I can figure
out HOW to make a negative that works for me.

--shannon

PS thanks for the link to the page about lith printing. That is very
interesting.
Received on Wed Jul 3 22:34:23 2002