Polarised!

Thursday 22 November we had a workshop on `Photography using Cross Polarisation organised by Michele Emslie. As you can see this involves using an LCD screen as the light source. This emits polarised light, in other words the light generated by the screen comes out in  a narrow angle. We all had polarising filters on our cameras and by rotating these we can block most of the light from the screen so it appears black or a dark magenta (Apple Retina screens).

At the top our light source (the Led’s in the laptop screen). Then the polarising filter (the Liquid Cristal Display), at the bottom the polarising filter on the camera rotated by 90 degrees so the screen appear dark.

If we then put a transparent  object in front of the screen that has some degree of polarising capability (because of internal stress or molecular structure) the polarised light gets rotated and not blocked anymore by the polarising filter on the camera. Clear plastic things like cups, cutlery, CD case, safety specs all do this to varying degrees, as you can see from the images captured on the night. The different colours are related to the thickness and the stress in the plastic, the light gets rotated more when the plastic is thicker, as it has to travel a longer path.

This image by Alan Meek shows that the laptop screen appears black, because he has his polarising filter at 90 degrees to the light emitted by the laptop screen. The forks rotate the light a bit so some of it is not blocked by the filter.

A few images of club members in action, we had to turn the lights off in the room to avoid reflections and spoiling the colours, hence it was a bit dark apart from the laptops lighting up the room.

The women’s section: Susan, Kirsty and Eileen.
Team Murty
Alan Meek at work, with (L2R) Michele, David and Martin in the background.
Michele checking if Trevor is following the instructions?
Mike from Team Murty at the controls.
Trevor fine tuning his set up. You can see that the screen is dark but the plastic cup is bright, as I took this shot with a polarising filter on my camera.
Kirsty Russell took this shot after drinking most of the Pimm’s. 😉
Another still life of the Pimm’s jug, this one by Susan. Obviously no Pimm’s left at all now!
David Drage made these plastic chess pieces specially for the event!!
Crossing forks and crossed polarisers by David Drage.
In sharp focus by Trevor Stuchbury.
Forked specs by Trevor.
Triangular composition by Alan Meek.
Clearly empty by Susan Gordon.

We all enjoyed this evening and since this is easy to do once you know how, I’m hoping to see more of these images from our Visionaires.  Many thanks to Michele Emslie for organising the evening.

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