RE: palladium vs. cyanotype sharpness

The imagesetter was in 3600dpi mode (image resolution was 3600 / 16 =
225dpi - in order to get all 256 tones) but of course the dots I was
seeing were neither the tiniest dots that the imagesetter was capable of
printing, nor 225dpi "pixels". Since tiniest dots would be present only
in the shadows of the print (near to clear sections of the negative)
they would be unnoticed or confused with something else. The dots I'm
writing about were observable (with the aid of a 10x loupe) starting by
30% - 40% density (white dots), up to 97 - 98% (black dots) - this is
with test target without applying any process adjustment curve. So, the
dots I was seeing were equivalent to let's say... 225 / 30% = 750dpi, or
at least 224 / 40% = 562dpi (I'm not sure if this calculation is
correct, maybe list members experienced in pre-press subjects will add
to/correct the information). It seems that our observations are
concordant.

Regards,
Loris.

-----Original Message-----
From: Jeffrey D. Mathias [mailto:jeffrey.d.mathias@att.net]
Sent: 21 Eylül 2005 Çarşamba 14:30
To: alt-photo-process-l@sask.usask.ca
Subject: Re: palladium vs. cyanotype sharpness

Loris Medici wrote:
> ...
> I have 3600dpi imagesetter negatives (for Cyanotype) printed on smooth

> paper which clearly show the (non visible to the naked eye) dots ...

A consideration should be the resolution that the paper used is capable
of rendering. I have found a smooth paper like Crane's (Cover, Business

Card Stock, "Platinotype") only resolves 600 lines per inch. Any
resolution beyond that is "hidden" by the paper surface. The way I use
to determine paper resolution is to make a negative with various
resolution target lines, print it with the process and paper selected,
and view with a magnifier or microscope.

This does not mean that the 3600 dpi is useless as the extra resolution
might be able to be used to produce more tonal "bit depth" in the
roughly 600 dpi dot (not taking into account loses from dot gain, etc.)

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/