Polariser question

EdMoss

EdMoss

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I was taking some portraits a couple of weeks ago of someone sat at an imac, I used a polariser to kill the screen reflections, except it also removed what was on the screen as well.
As I understand it a CPL removes reflections so why would it take away the screen display as well?
 
The monitor (and LCDs in general - try a calculator) uses polarisation to display light and dark areas, by manipulating different areas via an electric field. As a result, the light that is produced is polarised as part of the function of the monitor, meaning that the filter will block it out if aligned correctly.

More detail:
An LCD screen is made up of two polarised layers. When switched on and operating with no field across an area (pixel), the polarisation of these layers is aligned and you see a "lit" area coming from the backlight behind. By applying an electric field to one or more areas of one of the two layers, we can orient that layer at 90 degrees polarisation to the second, meaning that no light from the backlight can pass through, creating a "black" area.
By putting your polarisation filter in front, you're manually doing what your monitor does via an electric field application to display a black screen.
 
If you rotate the filter 90 degrees, it has no effect. The screen image will appear as normal.
 
Syx said:
The monitor (and LCDs in general - try a calculator) uses polarisation to display light and dark areas, by manipulating different areas via an electric field. As a result, the light that is produced is polarised as part of the function of the monitor, meaning that the filter will block it out if aligned correctly.

More detail:
An LCD screen is made up of two polarised layers. When switched on and operating with no field across an area (pixel), the polarisation of these layers is aligned and you see a "lit" area coming from the backlight behind. By applying an electric field to one or more areas of one of the two layers, we can orient that layer at 90 degrees polarisation to the second, meaning that no light from the backlight can pass through, creating a "black" area.
By putting your polarisation filter in front, you're manually doing what your monitor does via an electric field application to display a black screen.
Click to expand...

Thanks for that, now know not to try it again ;)
 
so its into photoshop to add an image on the screen or maybe a reshoot? :)
 
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