Re: Screen Photographs

[John Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Fri, 29 Dec 1995 19:07:29 -0600
>From: GCheski@xxxxxxx
>Subject: Screen Photographs

>I have some software that I use to create 3D images.  I can create left and
>right images and would like to experiment with putting them onto film.  Does
>anyone have any experience in photographing computer screens? I know there is
>a problem with "bars" appearing in the image due to scan rates of monitors.

>Gary Cheski

This has been discussed several times in the past. In case it's not in the
FAQ file, here are some techniques you may find useful, based on my experiences:

 - Try for a very slow shutter speed (at least 2 frames, preferably a 
   significant fraction of a second or more). (Basically eliminates scan
   artifacts such as bars. Methods can include use of slow film, small
   aperture, and turning down brightness of display.)
 - Use a tripod. (Permits slow shutter speed, assures uniform positioning for
   multiple shots. For even greater steadiness, you may want to also use a 
   cable release, self timer, or both.)
 - Use a long focal length lens. (Lets you fill the frame with the display,
   reduces distortion of image, which would be particularly bad with a curved
   screen.)
 - Use a very small aperture. (Increases depth of field for better focus -
   important for curved screens. Also helps get lower shutter speed.)
 - Photograph in a dark room. (Provides tremendous improvement in contrast
   and general image quality.)
 - Make sure camera is on line with center of display. (Prevents trapezoidal
   distortion from misplacement of camera.)
 - Clean screen, make sure display is adjusted correctly. 

Use of all these techniques should produce very good results - for instance,
a text screen should be easily readable. They will also work for video (i.e.
a freeze-frame image from a VCR or a scene from a video camera), bearing in
mind that the image quality of video is usually poorer than that of a good
computer display.

More advanced and higher quality techniques are available, which don't
involve photographing a CRT.

John Roberts


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