Xref: utzoo comp.graphics:3726 rec.photo:3778
Path: utzoo!attcan!uunet!husc6!mailrus!iuvax!pur-ee!3ksnn64
From: 3ksnn64@pur-ee.UUCP (Joe Cychosz)
Newsgroups: comp.graphics,rec.photo
Subject: Re: photographing computer screens
Message-ID: <9900@pur-ee.UUCP>
Date: 25 Nov 88 18:12:29 GMT
References: <18196@ames.arc.nasa.gov> <2709@pixar.UUCP>
Reply-To: 3ksnn64@pur-ee.UUCP (Joe Cychosz)
Organization: Purdue University Engineering Computer Network
Lines: 70

In article <2709@pixar.UUCP> good@pixar.uucp ("It's kind of fun to do the impossible." -- Walt Disney) writes:
>In article <18196@ames.arc.nasa.gov> watson@ames.arc.nasa.gov (John S. Watson) writes:
>:
>:[this discussion started in comp.graphics]
>: 
>:Here's how I get 24 bit photographs of my images from my 8 bit Sun screen
>:(The basic idea is to triple expose the film, once with each R,G,B channels).
>
>You can also get pretty good results just shooting off the monitor. I
>routinely make slides here with Ektachrome 100 and a 200mm Macro Nikor.
>Off our Barco and Sony RGB monitors I wind up with 1 second at f5.6.

I agree, however I use a few different settings.  I also shoot Ektachrome
100 (Ektachrome 64 is no longer available).  For prints I use standard
Kodak 100 print film.  

Setup:
   This is the longest and most crucial step.  It is important to get the
lens as perpendicular as possible to the screen.  Things to watch for are
monitors which tilt (like Suns or SGIs).  I also try to get the lens as
close as possible to the screen and still be able to focus. This helps
reduce the effects of the curvature of the screen.  For a 70-210mm Macro
Nikon this is about 2 ft.  

Exposure:
   I use a 1/2 second exposure at f8 with half a stop added in.  To bracket
the exposure I also shoot a f5.6 and a f11 exposure.  With 100 speed film
the exposure can be fairly forgiving.  That is to say, you'll get a
reasonable picture as long as the exposure and f-stop are within reason.
Never shoot faster than the refresh rate of the monitor.  This even
goes for taking pictures of monitors sitting in rooms.  If you do you
will endup with black bars on the screen.  For room shots I use 
1/8 second or longer.

Processing:
   For prints I usually tell the people that process my film that the
roll contains computer graphics.  Many film printers are computered
controlled and are setup for printing people, sky, grass, trees and other
things which you would find in normal photos.  These printers usually
lose it when the get a picture with lots of black.  Vectors are the
hardest to process.

   One other problem the film processing machines have is alignment.
Lets say you are shooting pictures of some square 512x512 images.
The film processor will more than likely assume that the left edge
of the image is the left edge of the picture.  I will not center it for
you.  This will also happen with slides.  To solve this problem two
things can be done.  One: shoot a few fully exposed pictures at the
beginning of the roll so the machine can set where the left edge is
for the rest of the roll.  Or two: us an alignment background pattern
like I do.  This looks something like this:


		----------------------------------
		!		!		 !
		!		!		 !
		!	-----------------	 !
		!	!		!	 !
		!	!		!	 !
		!-------! Image         !	 !
		!	!		!	 !
		!	!		!--------!
		!	!		!	 !
		!	-----------------	 !
		!		  !		 !
		----------------------------------

I'll have to try a 1 second exposure at f5.6 in the next roll I shoot.

Joe Cychosz