Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uwm.edu!uakari.primate.wisc.edu!xanth!mcnc!rti!sunpix!nick From: nick@sunpix.UUCP ( Sun Visualization Products) Newsgroups: comp.graphics Subject: Re: photographing screens Summary: use LONNNNGGGGG exposures Message-ID: <1016@greens.UUCP> Date: 28 Nov 89 21:08:06 GMT References: <3777@hydra.gatech.EDU> <18678@watdragon.waterloo.edu> <1788@crdos1.crd.ge.COM> Organization: Sun Microsystems, Research Triangle Park, NC Lines: 66 Forgive me if this goes out twice - I got back some garbage and am trying from a different machine --------------------------------------------------------- In article <18678@watdragon.waterloo.edu>, rsingh1@dahlia.waterloo.edu writes: > In article <3777@hydra.gatech.EDU> robert@shangri-la.gatech.edu (Robert Viduya) writes: > >Has anyone advice or pointers to information on how to photograph video > >screens? > ..... > > Shutter speed I used was, if I remember correctly, quite short. I guess > you want a shutter speed faster than 1/60th of a second (ntsc). I played > around with lots, so I might be wrong on this. > Maybe everyone knows this, but here are some hints gained from long years of experience - some of my screen shots are in the first SIGGRAPH proceedings (1974). Your monitor is putting up a complete picture in 1/60 (noninterlaced displays) or 1/30 (interlaced) second. If you use a shorter exposure, you won't get the whole picture. Your best bet is to use 1/2 second or 1 sec - if you get 15.25 or 29.75 frames it won't matter too much - assuming you've got a still image on the screen!!! I find Ektachrome 100 or 200 does pretty well - stop down to f/8 or so and you'll have some depth of field to accomodate CRT curvature. Always bracket your exposures +/- a stop or two. Using up film is much less of a pain than going through the whole process all over again. If you use your meter to check exposure, remember to consider your total image - if you meter a small white area (text) on a big black background, you'll get the wrong answer - by a couple of stops !! Think of it this way - your camera meter will give you a great exposure of a grey object. If what you meter is mostly black, then the camera will try to make that grey - close down to make it black again. If you are shooting black text on a white background, then open up a few stops. Record what you shoot - look at the results and write them down for future use - assuming you don't fiddle with the brightness and contrast in the meantime. Another hint is to use a longer than normal lens (for a 35mm camera, don't use the 50mm lens, use 85mm or 105mm or so). This'll put you further away from the screen, but will help with the perspective distortion. Always use a tripod of course. And if you don't have a cable release, try using the self-timer on your camera. That way you'll have your big shaky hand off the camera when the shutter opens. On some cameras, there is an added bonus as the SLR mirror will swing up at the start of the self-timer period, vibrations will dampen down, and then the shutter will open. Much harder to do, but better is to build a gadget that'll blank video, open your camera shutter, unblank video for exactly one (or N) frames(s) and then blank the video again. If you don't know how to build such a gadget, find someone who does. Use in a dark room of course !! Finally, if possible forget all this stuff and use a machine made for the job (Matrix Instruments or whoever) if you've got the $$$$. Nick England Director, Visualization Technology Sun Microsystems Inc nengland@sun.com Brought to you by Super Global Mega Corp .com