Ben.bb wrote:Would anyone care to share for us youngins
What Cross Polorisarisation is and how one goes about experementing with it?
Ben, my basic understanding is
Cross polorisation (in very simple terms) allows you to capture the light spectrum of objects , how light refracts due to the physcial construction/density and stress within an object, by applying two polarising filters at different angles. I believe it is used as an engineering tool to identify stress tolerances in construded objects by observing both the colours and patterns produced - but recommend an intranet search will be more accurate on technical specifics and I'm sure other form member will have more knowledge.
But with respect to what I have done here ..
Up until a month ago I had only seen the effect when I wore poloroid sunglasses and turned sideways looking through tinted laminated windows on my car - and then only to a slight degree when the angle was right 'the rainbows' could be seen created by the safety glass joins within the laminated windscreen.
A couple of magazines ( one being Digital Camera Feb edition) ran an article on it as a photographic technique which interested me ...so I gave it a try
get a light source (I used a light box because I had one but a table lamp will work)
place a polorised film or filter on it (I found a sheet of film but a pair of poloroid sunglasses or a camera filter will work)
place a clear plastic object on top (I found the clear hard plastics work best)
then using a circular polorising filter on your camera lense (I used a cokin) - rotate until the best effect is obtained through the viewfinder
turn off other light in the room (as it seemed to work better)
point and shoot
I played a bit with camera settings to get the best exposure, turned the flas off ..and voila
close up of a plastic bowl, lid of my cokin filter box, a chess piece resting on the base of the plastic bowl, and the plastic dome of a cheap battery touch light ...cellophane is also a good subject
I am now moving on to drinking glasses, cutlery and whatever else I can find in the $2 shop ..
my end result will be a couple of 'funky' posters for my sons room (a little reminence of the seventies for those old enought to remember)
Hope this is enough info to get you started having fun
DebT