Originally posted by lefei
What's the diff?
Originally posted by Ian
The difference is how the polarizer deals with light, linear polarizers polarize light in a linear fashion, while a circular polarizer consists of a linear polarizer and a 'depolarizer' that scatters the linearized light in a random manner.
Originally posted by mervlam
Actually, a linear polariser consists of only a layer of polarising film. But a circular polariser consists of both a layer of polarising film plus a quarter-wave plate. You have to learn some physics of light at university level to know what is a quarter-wave plate. I had forgotten...... :embrass:
a circular polariser actually polarise light in a same manner as a linear polariser, just that the behaviour of the polarised light is different. Therefore, circularly polarised light does not interfere with the metering system of an AF camera
Originally posted by roygoh
I believe the quater wave plate rotates half of the linearly polarised light by 90 degrees as well as delay the propagation by a quarter wavelength. The resulting wave has 2 components of E field, orthorgonal to each other and with 90 degrees phase difference. If you plot the E field at any point against time, you actually get a vector turning in a circle with constant amplitude. That's why it is called a circular polariser. Just my guess.
Originally posted by mervlam
ar... yes u are correctly.... u DO remember your work. :thumbsup:
Originally posted by mervlam
Actually, a linear polariser consists of only a layer of polarising film. But a circular polariser consists of both a layer of polarising film plus a quarter-wave plate. You have to learn some physics of light at university level to know what is a quarter-wave plate. I had forgotten...... :embrass:
a circular polariser actually polarise light in a same manner as a linear polariser, just that the behaviour of the polarised light is different. Therefore, circularly polarised light does not interfere with the metering system of an AF camera
Originally posted by roygoh
Recently I was reading Issac Asimov's "The Left Hand of the Electron" and in one of the articles discussing Newton and his contemporaries' experiments to understand light, he mentioned about crystals with molecular structures that rotate the polarity of light. The amount of rotation is proportional to the thickness of the crystal the light passes through.
That's how I got the idea of what a circular polariser actually is. Haven't verified my idea with any physics guru yet.
not much info on the search...anyway, i've gotten a circular polarizerOriginally posted by roygoh
By the way this topic has been discussed numerous times before. Do a search on "polariser" and you will get a lot of useful information.
Originally posted by mervlam
But 1/4 wave plates are stated as a mica quarter-wave plates on most American physics textbooks.
Originally posted by Ian
Since when were the Yanks known for using correct terminology
Originally posted by stl
If i have 2 lenses with different filter size eg 55mm and 62mm. what is the converter called? or there is no such thing? meaning i have to purchase 55mm and 62mm filters...
Originally posted by ckiang
You SHOULD buy a 55mm and 6mm filters, helps to boost the economy. ;p
Otherwise, you can get a stepping ring of the correct size. E.g. for your example, you would get a 62mm polarizer filter, and get a 55 (lens)->62mm (filter) stepping ring.
Regards
CK