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View Full Version : tablet and computer screen, refresh rate?



jnanian
2-Mar-2014, 18:58
ive previous experience photographing t v screens and i am thinking out-loud about photographing tablet or phone or my computer monitor ...
do they have refresh rates like my old tv did / does ?

if so, what might be an optimal shutter speed to expose my black and white film, any suggestions ?

thanks in advance

john

Jmarmck
3-Mar-2014, 08:03
Google "refresh rates" for the systems you are interested in.
For older CRT monitors > 60 sec. (60Hz)
Modern displays range from 50-60 frames per second to 120 Hz and 240 Hz. It depends on the make and model of the monitor. This is what you are given as a sales pith. But the higher rated LCD monitors will allow higher shutters speeds. I could find no rule of thumb but I would suggest the "refresh rate" x 2 for exposure time. For a 60 Hz CRT use 1/30 of a second or a 120Hz use 1/60 of a second. Plasma screens are different as they do not have a normal refresh rate. I have taken shots of my screen and never gotten a scan line. Phones? Who knows. There are so many different one with such a jumble of specs that it is hard to tell I would suggest starting with 120 Hz and work your way up.....or down.

Good luck

Larry Gebhardt
3-Mar-2014, 08:45
My understanding of LCD displays is they do not cycle the pixels like a CRT tube did (the electron beam redrew the whole screen 60, 72 or more times a second). This is because the phosphors needed to be continually refreshed to show an image. The refresh rate on LCD really is only relevant when you are talking about movement (changing pixel values). If the pixel doesn't need to change it will stay constantly set at the same value, so no flicker. For photographing a static LCD screen my guess is the shutter speed makes little to no difference.

jnanian
3-Mar-2014, 09:07
thanks for your helps !

larry i photographed a screen after i posted this question
at speeds from 1/2S - 1/250th ... and they all looked the same ...

john

Darin Boville
3-Mar-2014, 09:19
Try it again at 1/8000--no difference still...

--Darin

jnanian
5-Mar-2014, 07:24
thanks for your helps !