Re: Laser half tone negs.

grhen (grhen@ix.netcom.com)
Tue, 25 Jul 1995 23:34:38 -0700

You wrote:
>
>>You wrote:
>>>I am new to alt-photo-process and am wanting to start doing gums
with
>>the
>>>long term goal of doing full colours.
>>>
>>>I have been put off for a number of years by having to make large
negs
>>but
>>>now have access to a scanner, adobe photoshop and a laser printer.
>>>
>>>If I were to produce half tone negs on acetates using this set up
>>would they
>>>be appropriate for gum prints?
>>>
>I know that a number of people have been experimenting with Iris
printers
>to obtain separatations. They are capable of about 1200 to 1600 dpi so
^^^^^^^^^^^^^^^^
>reasonable screens should be possible.

I think you may be confusing the dpi output with the dot size of the
ink. My understanding from the people at Ilford is that the output
resolution is 300 dpi, but the size of dot that the ink makes is about
1/1800th of an inch. Therefore the 300 dpi dot is made up of numerous
1/1800th dots.

>If you are using a laser printer try to use one capable of at least
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>600 dpi.
^^^^^^^^

I once aquired samples of output (type and graphics) from different
lazer printers in order to determine which one was sharpest (we needed
to make line copies and then photo-composite to negs for murals). One
company sold an 800 dpi model and one a 1200 dpi model, yet none were
any sharper than the 600 dpi models. The partical size of the dyes
which were fused to the page by the lazer printer were pretty
consistent across the brands. Therefore the sharpness did not increase
with the printers ability to create smaller dots. All dots had the same
raggedness to them when viewed with a loop. As a matter of fact the
smaller (800 dpi and 1200 dpi) dots showed off the raggedness more than
the 600 dpi did. It should be noted that the 600 dpi was far and away
of much better quality than the 300 dpi.

>Luis Nadeau
>NADEAUL@NBNET.NB.CA
>Fredericton, New Brunswick, Canada
>

-- 
Guy Manning
grhen@ix.netcom.com