Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!exodus!nelsun.Eng.Sun.COM!srnelson From: srnelson@nelsun.Eng.Sun.COM (Scott R. Nelson) Newsgroups: comp.graphics Subject: Re: HELP NEEDED IN PHOTGRAPHING SCREENS Message-ID: <6710@exodus.Eng.Sun.COM> Date: 28 Jan 91 16:58:36 GMT References: <1991Jan27.232910.22575@ms.uky.edu> Sender: news@exodus.Eng.Sun.COM Lines: 84 From article <1991Jan27.232910.22575@ms.uky.edu>, by munish@s.ms.uky.edu (Munish Mehra): > Does anyone have some tips on photographing computer screens. > There was a discussion about a year or two ago, does anyone have > a copy or pointers to it. > I'd appreciate any help. > I have a Cannon EOS Rebel with a 35-70 Zoom, so I guess that should > be good enough. > Thanks. First of all, I assume you are photographing from a color monitor. You will (obviously) need a tripod to hold your camera. A cable release is helpful in reducing camera vibrations, but it is not absolutely necessary. A good daylight film produces best results on a color monitor because it is sensative to the same colors as the phosphors on the monitor. For slides, Ektachrome 100 works well. For prints, Ektar 25 is probably the best you can get. The slower the film speed the better the results you can expect. You are more likely to get a good color match with slide film because the photo processing lab does not attempt to do any color adjustments on slide film. Nearly all prints have some color adjustments done on them which can change your results. Before you start shooting pictures, make sure the color CRT is totally clean. The darker the room the better. Be sure there are no reflections off of the CRT from any other light sources. It is also a good idea to make sure no other bright CRTs are nearby. Align the camera and screen so that the screen is centered both vertically and horizontally relative to the lens of the camera. I would recommend using the 70 mm setting on your zoom lens to minimize the distortion caused by the curvature of the CRT. The further back you place the camera from the CRT the less distortion there will be. I would also recommend turning off the autofocus on the camera and getting the picture properly focused once and leaving it there. Because the electron beam sweeps over the face of the CRT somewhere between 50 and 76 times per second, you want the exposure time to be very slow. I prefer to catch at least 10 sweeps of the electron beam to guarantee even light distribution. I never set the speed faster than 1/4 second. The light metering system on your camera will give you a good general idea of the correct F-stop to use. If you want the very best pictures from a CRT screen it is recommended that you bracket the exposure by shooting half an F-stop to either side of what your camera recommends, in addition to using the setting the light meter selects. The last good set of pictures I did were shot using Ektar 25 film at 1/2 second exposure with the F-stop set at 2.0 to 2.8. Your camera only has a maximum F-stop of 5.6 at the 70mm lens setting (I just got one for Christmas), so you would probably want to set the speed to 1 or 1.5 seconds if you are using Ektar 25. If you must have prints and want the best color reproduction, you will probably have to take something to the lab that they can use to match colors. The image called "lenna" is an excellent one for getting good color matching, since any good photo lab can produce a correct flesh tone. If you have a color digitizer, you could digitize a photograph containing the colors you are concerned about, photograph this from your screen, then have the lab match the colors. I haven't tried this yet, but plan to do it. Most good photo labs are willing to work with you to get the exact colors. Once you get it right, make sure they write down the settings they used so that you can reproduce the results. If you are shooting many different images, keep in mind that brighter images may need a different exposure setting than darker images. This should be obvious, but I ran into the problem once. That is everything that I can think of, but I would appreciate hearing other photography hints that I haven't mentioned. --- Scott R. Nelson srnelson@eng.sun.com Sun Microsystems "Proofread carefully to see if you any words out."