Polarising Filter - Screw or Cokin?

Wishing to buy a new polarising filter. Can't make up my mind whether to get a screw on type or Cokin.

I already have a Cokin 'P' system of graduated and ND filters plus holders and full set of adaptors rings for 49mm to 82mm lens threads.

I would guess the polariser would mainly be used on my 17-70mm lens which has a 72mm thread but maybe also on a 55-300mm with a thread of 58mm and a macro lens of 55mm thread. I also have a 10-20mm wide angle with a 77mm thread but would probably not use the polariser on this lens.

Common sense(?) tells me to get the Cokin filter, but my question: As the polariser will be on my 17-70mm for most of the time, is a screw on filter a better choice.

I should also add that I often go out walking with camera and the 17-70mm lens only, in a holster type bag. It would be much easier to leave a screw polariser on the lens than probably having to attach/unattach a Cokin filter.

Plus, I suppose if I bought a 72mm screw-on filter I could use step-up rings to attach it to the 55-300 and macro lens for the odd time I may need to.

Guess I'm starting to answer my own question..!!

Thank you.

Its sounds like you already know this .. obviously the Cokin system type Polariser will prove far more flexible - the system allows the one (circular) filter to be used with all of your lenses.

When I used one I didn't find it any problem to keep the filter holder with polariser attached to the camera & lens, even when moving around with it all in a bag - Cokin provide a handy plastic front cover that fits in the fist slot of your holder and protects any filters behind it.

I have always felt the problem with Cokin style filters is that they are very vulnerable to reflections. OK, we can use their lens hood, but what a cumbersome outfit it makes.

A screw-in circular polariser can be used quite successfully even with original Pentax hoods, just remove the small window so that the filter can be turned.

A screw on one should prove more convenient and usable with the original lens hoods (the Pentax ones have that slide out section specifically to allow rotation.)

A bumper bundle of step-up/down rings here for a reasonable price.

http://www.ebay.co.uk/itm/49mm-82mm-Step-Up-Rings-UV-CPL-Set-82mm-49mm-Filter-St...

I would think the Cokin polarizer would be far more cumbersome when it comes to rotating it. I've used their NDs but not polorizers for that reason.

John K

I prefer screw in filters for the reasons stated above. Be aware that using a polarising filter on the DA 55-300 can be troublesome. It is never a speed demon, but I have found it hunts a lot with a filter attached, no doubt the quite F5.8 max aperture at the long end does not help.

Regards - Steve

Thanks everyone. With regard to the small removable window on Pentax hoods, it's a shame Sigma never thought of that!

I never found it cumbersome - the polariser has a slatted rim which allows easy movement with the fingers from top, bottom or both. And it can still be done even with another square glass filter fitted in front of it.

They'll be plenty of landscape situations where you'll want both a polariser and ND grad, and so the filter holder system remains most flexible in that regard. I take the point about extra light bouncing around possibly. But surely the holder with its slots is easier to manage than having to fit the step up/down rings and attach the filter again each time?

Guess it's what you get used to. With my film cameras I managed perfectly well with just a 49mm thread one on my M lenses. Never needed anything else!

John K