[nikonuser11]

you all know I only got my DSLR a few weeks ago so still learning and asking a zillion questions..............

1) just got a CPL but I read somewhere that you have to turn it depending on which way the sun is hitting your lens to get different effects, is this true as I cant see anything about this?

2) A Hood (flower petal shaped thing) came with my new Sigma 17-70 lens (which I've already put a UV filter on) so when would I use this hood and whats the pro's/cons?

thanks

[Spod]

A CPL bounces stray light so you only end up with direct rays of light, depending on where you have the CPL spun round to determines what light is bounced from where. The easiest thing to do is put it on and look through the viewfinder as you spin it around. On a sunny day it should enrish colours but not always that obvious depending on where the sun is in relation to you, the best way is to find a pond and look down into it, you'll be able to see through into it or the surface reflection depending on where the CPL is.

[Spod]

Here's a link

As for the hood again they stop stray light but causing lens flare this time, a lot of people like myself use them as a form of protection as well, I'd rather dink a bit of plastic into something than the glass on the end of the lens

[weetsie]

on a 17-70 the lens hood will be fairly small so i would have it on the lens always and put it on backwards whenever i put my camera in my bag.

[T0MAT01]

Originally Posted by weetsie

on a 17-70 the lens hood will be fairly small so i would have it on the lens always and put it on backwards whenever i put my camera in my bag.

I agree. The only reason not to use it is if you're trying to use the on board flash which can sometimes cast a shadow if the lens hood is in place. Other than that it doesn't do any harm.

As for the CPL, it has a little marker on it which is supposed to be pointed towards the sun for maximum polarization, but of course you don't have to. You can just turn it until you like what you see through the viewfinder.

[nikonuser11]

thanks guys, so it seems just 'fiddle about' with the CPL till I like the image and ideally dont go too wide ie17? or it makes different areas of the sky a different shade of blue.

Still dont get the Hood, just use it as a lens protector then (I have a UV filter already on) or is it more accurate onboard metering from the camera?

[Spod]

Here's a good site for an explanation of what a lens hood does.