Originally Posted by rich
The target card doesn't appear totally blue - or at least my brain tells me it isn't blue - so some frequencies other than blue are getting through the pigmented plastic.
That's your brain Rich and everyone elses
That bright orange square on the side? That's exactly the same colour as the dark brown one top face on the cube.
A & B... same brightness and grey.
What you see as normal colour is because your brain has said "ooh it can't be all that blue cos it's a white target"... and made it such.
The effect can be quite long lasting. Spending a year making lots of red images on screen it wasn't uncommon to walk away from the computer and see everything in green for a bit!
We will have to wait till summer. But i've done these experiments in constant light on a constant target with me constant in the shade with heated scopes, and the temp was what moved them. You could see it happening as they cooled down.