I have seen many bad pictures of LCD and CRT screens. How do I get a good picture of an LCD or CRT screen?
It's not very hard to take a good photo of an LCD or CRT screen. I'll add oscilloscope in here as a special case of both as I've taken meany such over the years. A few pointers. Some of the following may sound complex at first glance but it's all fairly intuitive taken a section at a time.
CRT frame rate will vary with screen mode - you can look it up or check the computer video settings - or just try different shutter speeds until you get one or several that are best. Be aware that frame rate may change if you change the mode.
Using exposure times that are not equal to these can give partial pictures with bright or dark areas or no picture at all if you are especially clever.
Take a series of images at rates from say 0.1 s to 0.01 and faster and see what "artifacts" appear. There will (probably) be a shutter speed that best suits and after that you use aperture and ISO and leave shutter speed alone.
I just tried various speeds on a 1080p plasma screen and anything below 1/90th second is good. Above 1/90th the image artifacts are bizarre and almost inexplicable.
A CRT oscilloscope usually scans left to right but a modern LCD screen oscilloscope may combine trace write time with frame writes, so start playing.
Once you are happy with shutter speed effects:
With an oscilloscope, if it has an "illuminated graticule" adjust the level to look good – not blazing bright with regard to trace and not invisible.
LCD screens' best viewing angle will vary with contrast setting. If contrast is not adjustable you may find that an angle above or below horizontal works best.
I believe the technique would be the same as described here - Why I can't take a clear photo of a TV.
Because of the way the screen refreshes (redraws), your best bet is to have a shutter speed longer than the refresh rate. If it's 60Hz (1/60th second) then try 1/30th or slower. This way you won't catch it when it's halfway redrawn the screen. The longer the better, if the image on the screen is fixed.
If it's a show being broadcast, I hit the freeze button on my remote. If it's a move or tv show on dvd/blu ray, I either press the freeze button on my tv remote or hit pause on the dvd player remote. Today I took a bunch of shots at various shutter speeds. I have a Nikon D5100. Using a tripod I used ISO 100 and found the shots that came out best were usually shot at about F22 and 1/6 of a frame. I kept shooting at various shutter speeds to see what came out with no weird lines that my eye didn't see on my LCD HD tv, but my camera picked up.
Then, just using the basic photo editing software that comes with Windows 7, I cropped the shots and playe around with brightness, contrast, shadows and highlights a bit. But ont the whole the "lineless" shots, needed not tweaking.