bfag@uhura.cc.rochester.edu (Meneldur) (08/23/90)
Greetings. A question for those of you who have taken pictures of your VGA screens. What exposure time is most appropriate? I know it needs to be long enough to avoid the screen retrace, but what is optimal? I recently took slides of some color diagrams done with the paint program included in Windows 3. I figured 1/8 second should be adequate, yet the slides demonstrated broad diagonal swaths of darker colors that appear to be retrace related. Otherwise, the results were quite nice using the Zenith FTM monitor. Thanks for the help. I'd rather not have to use another roll of film experimenting with various exposure times! Bill Faggart Dept. of Geol. Sci. Univ. of Rochester Rochester, NY
urban@eecae.uucp (Mark Urban-Lurain) (08/23/90)
In article <9034@ur-cc.UUCP> bfag@uhura.cc.rochester.edu (Meneldur) writes: >A question for those of you who have taken pictures of your VGA screens. >What exposure time is most appropriate? I know it needs to be long enough >to avoid the screen retrace, but what is optimal? I've not yet tried my (new) VGA with NEC 3d monitor. However, I've taken slides of a Zenith RGB monitor. I found that Ektachrome film produced more accurate color than Kodachrome, plus it has the advantage of being able to develop it locally, rather than sending it to the great Yellow Father. I've always bracketed exposures, around 15 seconds +/- 2-3 secs at F8 so that the retraces average out. On my (not flat) RGB monitor, I found that using a 135 mm lens helped reduce the keystone effect from the curved monitor screen. I put the camera on a tripod in a dark room to avoid reflections/glare on the CRT. Getting the camera/tripod "square" with the CRT is a bit of a chore. I found that different images required different exposures, so you wind up wasting several shots per roll. -- Mark Urban-Lurain urban@cpswh.cps.msu.edu Computer Science Dept. urbanluraimg@clvax1.cl.msu.edu Michigan State University (517) 353-0682 A-714 Wells Hall, East Lansing, MI 48824
whh@PacBell.COM (Wilson Heydt) (08/24/90)
In article <9034@ur-cc.UUCP> bfag@uhura.cc.rochester.edu (Meneldur) writes: >Greetings. > >A question for those of you who have taken pictures of your VGA screens. >What exposure time is most appropriate? I know it needs to be long enough >to avoid the screen retrace, but what is optimal? The "classical" answer is to use the reciprocal of the full screen repaint time. Find out how long it takes to fully draw the screen and use that. (The reason I said "classical" is that for a TV set in the US, the time is 1/30 second.) >I recently took slides of some color diagrams done with the paint program >included in Windows 3. I figured 1/8 second should be adequate, yet the >slides demonstrated broad diagonal swaths of darker colors that appear to >be retrace related. Otherwise, the results were quite nice using the >Zenith FTM monitor. You may be having problems with a focal-plane shutter. The older leaf shutter didn't tend to do that. >Thanks for the help. I'd rather not have to use another roll of film >experimenting with various exposure times! Why not? Film and processing are cheap. Get a short roll (say, 12 exposure, you'll be spending no more than $5 or $6 for everything) and try different timings and apertures. Then makes notes somewhere you won't lose 'em--say a file on your system--and you won't have to do it again. --Hal ======================================================================= Hal Heydt | An earthquake is Mother Nature's Analyst, Pacific*Bell | "silent" pager going off . . . 415-823-5447 | whh@pbhya.PacBell.COM |
dlow@hpspcoi.HP.COM (Danny Low) (08/24/90)
>A question for those of you who have taken pictures of your VGA screens. >What exposure time is most appropriate? I know it needs to be long enough >to avoid the screen retrace, but what is optimal? > >I recently took slides of some color diagrams done with the paint program >included in Windows 3. I figured 1/8 second should be adequate, yet the >slides demonstrated broad diagonal swaths of darker colors that appear to >be retrace related. Otherwise, the results were quite nice using the >Zenith FTM monitor. 1/15 of a second should have been adequate. I have done screen shots that fast although mostly I shoot at 1/2 to 1 second due to the slow speed of the film I use. This is for US electrical cycle times. Danny Low "Question Authority and the Authorities will question You" Valley of Hearts Delight, Silicon Valley HP SPCD dlow%hpspcoi@hplabs.hp.com ...!hplabs!hpspcoi!dlow
eakin@rsmas.miami.edu (08/27/90)
In article <1990Aug23.151023.22700@msuinfo.cl.msu.edu>, urban@eecae.uucp (Mark Urban-Lurain) writes: > In article <9034@ur-cc.UUCP> bfag@uhura.cc.rochester.edu (Meneldur) writes: >>A question for those of you who have taken pictures of your VGA screens. >>What exposure time is most appropriate? I know it needs to be long enough >>to avoid the screen retrace, but what is optimal? > > I've not yet tried my (new) VGA with NEC 3d monitor. However, I've > taken slides of a Zenith RGB monitor. I found that Ektachrome film > produced more accurate color than Kodachrome, plus it has the advantage > of being able to develop it locally, rather than sending it to the great > Yellow Father. > I have found that Fujichrome 50 results in more accurate colors in photographing my IBM VGA screen. 1/4 second is the minimum shutter speed to eliminate the retrace problem, but I prefer to use 1/2 to 1 second. Using a 100-200mm lens and tripod in a dark room, I generally shoot around 1/2 second @ F11 or 1 second @ F16. However, I recommend that all shots be bracketed by one stop each way. The exact exposure will vary with the subject on the screen. -- C. Mark Eakin Internet: Eakin@RSMAS.miami.edu Amateur Radio: N4SYK Packet Radio: N4SYK@AB4LU.FL.USA.NA USnail: Univ. of Miami, RSMAS-BLR, 4600 Rickenbacker Cswy. Miami, FL 33149-1098
whh@PacBell.COM (Wilson Heydt) (08/28/90)
In article <15160004@hpspcoi.HP.COM> dlow@hpspcoi.HP.COM (Danny Low) writes: >>A question for those of you who have taken pictures of your VGA screens. > >1/15 of a second should have been adequate. I have done screen shots that >fast although mostly I shoot at 1/2 to 1 second due to the slow speed of >the film I use. This is for US electrical cycle times. As slow as you go, the refresh rate isn't going to matter. From the photographic side, though, you're risking problems with the color values due to reciprocity failure. --Hal ======================================================================= Hal Heydt | An earthquake is Mother Nature's Analyst, Pacific*Bell | "silent" pager going off . . . 415-823-5447 | whh@pbhya.PacBell.COM |