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Enlarger lens options.



 
 
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  #21  
Old May 12th 08, 01:16 AM posted to rec.photo.darkroom
David Nebenzahl
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Posts: 1,353
Default Screen angles

On 5/11/2008 5:09 PM David Nebenzahl spake thus:

By the way, the standard screen angles for 4-color (CMYK) printing a

K (black): 45°
M (magenta): 75°
Y (yellow): 90°
C (cyan): 105°


Interesting explanation of screen angles can be found at
http://www.dtp-aus.com/hlftone.htm (scroll down to "Screen(#) Ruling
and Angles").

Interestingly, it's not just a matter of reducing moiré effects; the
screen angles are selected to create "rose" patterns which, apparently,
are the least bad alternative (there will always be some kind of pattern
generated by multiple halftone screens, and this is thought to be the
most pleasing one).


--
The best argument against democracy is a five-minute
conversation with the average voter.

- Attributed to Winston Churchill
  #22  
Old May 12th 08, 06:34 AM posted to rec.photo.darkroom
Nicholas O. Lindan
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Posts: 1,227
Default Enlarger lens options.

"Jean-David Beyer" wrote

I make some 50% dots (my densitometer will measure % dot area)
and make the contact prints 50% ...


Brings back memories ... My firm designed a graphic arts exposure
integrator that had exposure adjustment in % dot gain (along with
stops, OD (for step-wedge test results), and straight %). Then
we designed nuVac for stochastic screening and the hell with
dot-gain. All about 20 years ago ... the dénouement of analog
pre-press.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.darkroomautomation.com/index2.htm
n o lindan at ix dot netcom dot com


  #23  
Old May 12th 08, 03:33 PM posted to rec.photo.darkroom
Jean-David Beyer
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Posts: 247
Default Enlarger lens options.

Nicholas O. Lindan wrote:
"Jean-David Beyer" wrote

I make some 50% dots (my densitometer will measure % dot area)
and make the contact prints 50% ...


Brings back memories ... My firm designed a graphic arts exposure
integrator that had exposure adjustment in % dot gain (along with
stops, OD (for step-wedge test results), and straight %). Then
we designed nuVac for stochastic screening and the hell with
dot-gain. All about 20 years ago ... the dénouement of analog
pre-press.

I just use a Macbeth densitometer TD-901 that has a %dot scale.

--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key: 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 10:25:01 up 5 days, 2:57, 3 users, load average: 4.05, 4.02, 4.03
 




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