Polarizer

[mangproc]

Hello all.
I am a weekend photographer, w/ a tight budget, & a reader of both photoplus & digital camera world.
I have a canon T1i w/ a sigma 18 - 200 lens & a UV filter attached to it. I am buying a Polarizer filter for this lens. (1) Can I put the polarizer in my lens, together w/ the UV filter? Which goes in first? (2) Can I also use the polarizer lens to shoot portrait?

Thank you in advance.

[GeoffWessex]

You could put a Polarizer on your lens, as well as a UV filter, but you may lose a couple of stops of speed...... and they have to be spotless.

Any extra glass (or plastic) put in front of a lens will degrade the image to some degree.

It also makes a difference with what kind of filters you mean - the screw-on glass filters, if clean, shouldn't be a problem..... square filters, on the other hand, can allow sidelight to creep between two filters and can deteriorate the image. I'm guessing you're using screw-on filters - I'd take the UV filter off if using a screw-on Polarizer.

Not a lot of point in having a polarizer for most portraits, unless you're outside and on a lake/river, or in bright sunshine (which is never great for portraits anyway)..... otherwise, I wouldn't bother.

[markgozz]

Geoff I didn't realize that you could put more than one screw in filter onto a lens at once , I don't have the screw in type just the Cokin P series . Are you limited to two filters per lens or is it dependent on each individual lens .

Sorry to jump in on your thread Andy hope you don't mind .

Mark

[GeoffWessex]

Yes, the screw-in filters usually have two threads - one to connect to the lens and one to receive another filter. I suppose you may find some budget filters without a 'front thread', but most have both.

The Cokin filter holder has two springs on each side to grip two filters quite firmly, but there's room for another in between. I can't really see of any occasion when I'd want to use three, but perhaps if I only had two ND filters and still wanted something extra for a very bright sky - it could take an ND Grad. I haven't tried any other square filter systems - but I'd like to!

[markgozz]

Thanks for the info Geoff , never new about the two threads .

I know what you mean about stacking too many Cokin filters , my filter holder will hold three square filters plus one circular filter like a polarizing filter but I have tried stacking three ND's to slow things down in day light and have ended up with hideous colour cast .

Time to invest in a 10 stop filter I guess

Mark

[OldBoy]

Originally Posted by markgozz

Geoff I didn't realize that you could put more than one screw in filter onto a lens at once , I don't have the screw in type just the Cokin P series . Are you limited to two filters per lens or is it dependent on each individual lens .

Sorry to jump in on your thread Andy hope you don't mind .

Mark

You mean like this: http://www.lensrentals.com/blog/2011...th-bad-filters

[markgozz]

I love the things people get up to when they have too much time on their hands

Thanks for the link OldBoy , apart from making my laugh it finally made the penny drop on how the screw in filters worked .

Some times I amaze myself on how slow I can be .

Cheers

Mark

[mangproc]

Thank you Geoff, and all.

[cosmicma]

UV filters arn't really needed on DSLRS as UV light is already filtered in camera so besides using a screw in filter to protect the end element they don't really serve a purpose anymore
on the other hand polarizing filters can be very useful for eliminating reflection and allowing the sky to have much better contrast
i would leave the UV filter out of the equation all together and just use the polarizer if it suites the purpose

if you do want to use a filter for protection UV are usually the weapon of choice but lenses in general have much tougher coatings nowadays and don't scratch as easily
lens hoods do a good job at keeping things away from the front element and are far more useful i would stick with one of those

[wavemachine]

One thing to watch that hasn't been mentioned is if you stack to many screw in filters you run the risk of vignetting at the wide end.

Originally Posted by markgozz

I know what you mean about stacking too many Cokin filters , my filter holder will hold three square filters plus one circular filter like a polarizing filter but I have tried stacking three ND's to slow things down in day light and have ended up with hideous colour cast .

Time to invest in a 10 stop filter I guess

Mark

Mark I have had the same thing and invested in a hi-tech 10 stop filter which seems pretty good although I do get a cyan colour cast with it, but that is easily corrected with a white balance adjustment and seems easier to correct than the cokins. The ultimate of course is the Lee big stopper but then you need to get the Lee filter mount system.