Filters and the like

[G-Kenny]

Well as some of you may know, i am kinda new to this stuff, i feel i have came on leaps and bounds since i started but now with the addition on my new sigma 10-20mm i was going to dip into the world of filter's.

basically what do they do?

i have ready alot about NDGrads so am pretty ok with them but i do not realy understand circular polarisers?
what is there affects?
are there any negative affects of a cpfilter?
will it work on the new 10-20mm?

Thanks in advance
G-Kenny

 

[michaelgreen78]

CPls cut down glare etc and give a deepness to blues. They can be tricky to use and on the 10-20mm lens they may give an uneven effect due to the extra width.

http://photography-on-the.net/forum/showthread.php?t=515090

See post #8 for my mini-test of filters on my sigma 10-20 lens.

 

[G-Kenny]

CPls cut down glare etc and give a deepness to blues. They can be tricky to use and on the 10-20mm lens they may give an uneven effect due to the extra width.

http://photography-on-the.net/forum/showthread.php?t=515090

See post #8 for my mini-test of filters on my sigma 10-20 lens.

Thanks for the link proved very helpful.
what exactly do you mean about the cpl's? ie how are they tricky and what causes the uneven effect on the wide angle?

 

[jerry12953]

how are they tricky and what causes the uneven effect on the wide angle?

With a wideangle you get a different amount of polarisation in different areas of the image - this is especially noticeable in skies. The wider the lens the worse it is.

You also lose about 1.5 - 2 stops with a polariser. So you may need to use a tripod. But having said that they are an essential filter for landscapes.

Try one out! You can see exactly the effect the filter is having through your SLR viewfinder.

 

[G-Kenny]

yea will probably try one out next time i get the camera out

i read somewhere that it has different effects when rotated differently is that the case??

 

[subseasniper]

A circular polariser is so called (if I am wrong please correct me) not because of the physical shape of the filter but because the effect the filter creates is spread over the glass in a circular pattern. Sorry, that is so untechnical. I used to have a square polariser that fit onto a Cokin filter system on my old film SLR and you could turn that in the filter holder to vary the intensity of the polarisation effect.

Beware they are pretty pricey for a 77mm thread so maybe check out the Hong Kong shops on ebay for a bargain.

 

[jerry12953]

There's no difference in terms of results between linear and circular polarisers.
Its something technical I don't understand.:bonk: