What's a polariser?

shuy · 20th April 2003

is it to take pictures on a really sunny day? it blocks reflections right? how does it to dat exactly? how is it different from a ND filter? how do i choose one? thanks!!

Sin · 20th April 2003

http://www.google.com.sg/search?hl=e...er+photography

shuy · 20th April 2003

thanks for the link! i was wondering how a polariser could selectively reduce reflections and nothing else, i wonder how it can tell the difference...

the guidelines were 35deg from the reflective surface, and 90deg from the sunlight. must this be strictly adhered to? it kinda restricts many angles rite?

any polariser to recommend?

mervlam · 20th April 2003

Quote:

Originally posted by shuy
thanks for the link! i was wondering how a polariser could selectively reduce reflections and nothing else, i wonder how it can tell the difference...

the guidelines were 35deg from the reflective surface, and 90deg from the sunlight. must this be strictly adhered to? it kinda restricts many angles rite?

any polariser to recommend?

as u said, those are guidelines.

polariser? you need to consult your camera's manual to see if you need either a linear polariser or circular polariser.

shuy · 21st April 2003

well, my manual doesnt say, but the article link says to use a circular one if i have an AF camera, which i do... how much is a decent one roughly?

mervlam · 21st April 2003

depends on filter size

bearycute · 21st April 2003

Quote:

Originally posted by shuy
thanks for the link! i was wondering how a polariser could selectively reduce reflections and nothing else, i wonder how it can tell the difference...

the guidelines were 35deg from the reflective surface, and 90deg from the sunlight. must this be strictly adhered to? it kinda restricts many angles rite?

any polariser to recommend?

When light gets reflected from a surface (eg water surfaces or glass), it beomes polarize in that plane it is refleced from. the polarizer have strands of molecules that is aligned in a particular direction. when light past through the polarizer, the molecules oscillate and absorb most of the energy of the light in the same plane as the molecules. Hence only light polarize in that plane gets absorb. The rest past straight thru. (actually, everything is affected but light polarize in that axis is affected the most)

HOwever, the reflection from shiny objects will not be greatly affected by the polarizer as the reflected light is not polarize in a particular plane. Hence, polarizer will not work in this case...

shuy · 21st April 2003

wah so cheem.... overdose of physics haha. thanks!

my adaptor fits 49mm... how much would that be roughly?

longman · 21st April 2003

actually polariser also can use as ND cos it cut off 2 stop of light too....

shuy · 21st April 2003

actually i want to get a polariser cos some of my pics look bland in the sunlight, i read that ND filters can be compensated by adjusting exposure, so i left that out. it seems a polariser can bring out the colour n contrast in sunny conditions...

longman · 21st April 2003

Quote:

Originally posted by shuy
actually i want to get a polariser cos some of my pics look bland in the sunlight, i read that ND filters can be compensated by adjusting exposure, so i left that out. it seems a polariser can bring out the colour n contrast in sunny conditions...

yup, solarise will help, but if without polarise, can try under 1/2 to 1 stop on sunny conditions, it also help...

SL6 · 22nd April 2003

Hi there,

may i know what's actually the diff between linear and circular polariser?

If i am currently using a AF digi cam and i use linear polariser,what will the effects be?

I just bought one A series colkin linear polariser from CP,and the sales guy knows i am using the canon S30,but he did not mention that it will be better to use circular.

Can anybody help me on this?

Should i go and get another circular polariser?

Thanks!

Ah_Seng · 22nd April 2003

Hi,

the earlier post by SL6 is actually me.

hmm.....dont know how come become SL6,though i logged in as eagles_creek.

Hey SL6,you stay in woodlands?Maybe you forget to log-out?

shuy · 22nd April 2003

u can read the link at the start of this thread, it said that circular polariser is better for AF cams... dunno the technical difference though.

i have an e-quote of $31 for the Hoya circular filter 49mm, is that gd? the B+W and Cokin ones out of stock btw...

Prismatic · 23rd April 2003

Linear polarisers DUN work for AF cameras. At least most of the time. This is because the AF system of your camera works by reading linear contrasts in the image. If you use a linear polariser, at certain angles, it will cut out the light from lines that the camera will need to read in order to get an AF reading.

mervlam · 23rd April 2003

not really.... depends on where the AF receptor is located. if the receptor is not TTL, then linear polariser should work.

shuy · 24th April 2003

i have an e-quote of $31 for the Hoya circular filter 49mm, is that gd?

Prismatic · 24th April 2003

Quote:

Originally posted by mervlam
not really.... depends on where the AF receptor is located. if the receptor is not TTL, then linear polariser should work.

Having an AF receptor which is not TTL is very impractical lah. Imagine your hands or something else blocking it while you are trying to take a picture. How many cameras can you name that the AF receptor is not TTl?

mervlam · 24th April 2003

I can name one: my good old Canon Prima 85N

Prismatic · 24th April 2003

Hello. You try fixing a polariser to that camera lah. Out-of-point siah. Must be you studying too hard oredi.....

20th April 2003	#1
shuy Member Join Date: Sep 2002 Location: Alpha Centuari Posts: 242	What's a polariser? is it to take pictures on a really sunny day? it blocks reflections right? how does it to dat exactly? how is it different from a ND filter? how do i choose one? thanks!!

22nd April 2003	#12
SL6 Member Join Date: Mar 2002 Posts: 146	linear polariser Hi there, may i know what's actually the diff between linear and circular polariser? If i am currently using a AF digi cam and i use linear polariser,what will the effects be? I just bought one A series colkin linear polariser from CP,and the sales guy knows i am using the canon S30,but he did not mention that it will be better to use circular. Can anybody help me on this? Should i go and get another circular polariser? Thanks!

22nd April 2003	#13
Ah_Seng Member Join Date: Apr 2003 Location: Land of the woods........ Posts: 1,306	sorry Hi, the earlier post by SL6 is actually me. hmm.....dont know how come become SL6,though i logged in as eagles_creek. Hey SL6,you stay in woodlands?Maybe you forget to log-out?

20th April 2003	#2
Sin Deregistered Join Date: Jan 2002 Posts: 136	http://www.google.com.sg/search?hl=e...er+photography

21st April 2003	#5
shuy Member Join Date: Sep 2002 Location: Alpha Centuari Posts: 242	well, my manual doesnt say, but the article link says to use a circular one if i have an AF camera, which i do... how much is a decent one roughly?

21st April 2003	#6
mervlam Senior Member Join Date: Apr 2002 Posts: 2,422	depends on filter size

21st April 2003	#9
longman Member Join Date: Dec 2002 Location: South Posts: 748	actually polariser also can use as ND cos it cut off 2 stop of light too....

23rd April 2003	#15
Prismatic Member Join Date: Feb 2003 Location: In the void. Posts: 1,215	Linear polarisers DUN work for AF cameras. At least most of the time. This is because the AF system of your camera works by reading linear contrasts in the image. If you use a linear polariser, at certain angles, it will cut out the light from lines that the camera will need to read in order to get an AF reading.

24th April 2003	#17
shuy Member Join Date: Sep 2002 Location: Alpha Centuari Posts: 242	i have an e-quote of $31 for the Hoya circular filter 49mm, is that gd?