[knumbnutz]

mmm, 82mm is for the 67 lenses and 77mm is for DSLR lenses.
Maybe no good?
Will have to check.
Cheers Neil

[Big G]

Pentax DSLR cameras do not use split beam metering systems. The AF is the only thing using a beam splitter (the mirror).
Metering is done off the focusing screen, just like they've done it with every SLR camera, film or digital, except for the LX.

Absolutely.

All the advice to me was "you need a CPL", I bought a Linear version, worked perfectly.

I have a Lee Linear Polariser, I don't use it often but I need it to go with the rest of my Lee filter kit. It's a bit of a faff, so it's no use when you're trying to work fast, but for slow paced Landscape work it's great.

I'm going to get the Hoya HD for when I go to NYC as I need to work quickly / compactly.

[StevenVH]

Another vote for stepping rings. I use a 52mm and 77mm CPL on 49, 52, 67 & 77mm lenses. And also using generic rubber and metal hoods attached to the filter to make for easy adjustments.

cheers

[amoringello]

Had a cheap $30 CPL for years. Finally bought some good lenses and a $250 CPL.
So far I have not noticed any differences to justify the price increase. It seems to polarize a bit more, perhaps. I assume under certain conditions the more expensive one also reduces glare to a greater extent. Sadly I have not run across the situations where that helps significantly.
So, unless you see a need, I would suggest grabbing a $30 Hoya CPL.

Because of the price I bought one 77mm CPL with a step-up ring. so that I could use it on both my DA* 16-50 and the DA*50-135 lenses. Although it does fit within the hood of the 50-135, the clearance is so tight that it is extremely difficult to remove the filter. I was close to breaking off the hood to get at the CPL with the step-up ring.

I have also never had any trouble at all when using linear polarizers. I think the issues may have been around with older cameras with different types of focusing and metering mechanisms. It just doesn't seem to be an issue with the way Pentax works. I have not heard any first hand experiences of problems with linear polarizers on most cameras made today.

[Spotmatic]

Pentax DSLR cameras do not use split beam metering systems. The AF is the only thing using a beam splitter (the mirror).
Metering is done off the focusing screen, just like they've done it with every SLR camera, film or digital, except for the LX.

Pentax Imaging recommended a circular. Yes, a linear will work but there is nothing to stop Pentax from altering the way they implement AF or metering in the future Also, if you are using the PL in bright sun a filter with superior coatings is the best option. I am in Florida, he is in Australia the sun in the frame/flare is a real issue so it makes no sense to use a cheap filter especially with a WA lens.

[Arpe]

You need a circular polarizer for digital.

Pentax Imaging recommended a circular.

I'm not saying anyone is "wrong" here but I have used a linear polariser quite successfully on my istDs and K20D in the past. Have yet to try it on my K-7.

[Wheatfield]

Pentax Imaging recommended a circular. Yes, a linear will work but there is nothing to stop Pentax from altering the way they implement AF or metering in the future Also, if you are using the PL in bright sun a filter with superior coatings is the best option. I am in Florida, he is in Australia the sun in the frame/flare is a real issue so it makes no sense to use a cheap filter especially with a WA lens.

I'm merely refuting your statement that he "needs a circular polarizer", which is plain and simply not true.
Pentax imaging recommends circular polarizers because the AF uses a beam splitter, not the metering system.
Where did cheap come into this, BTW?
Circular polarizers are, by there nature, more expensive to manufacture, but they are not necessarily optically better filters.
It is more difficult to find multi coated filters these days.
The sun, BTW, is an issue no matter where you are. I'm not so far north that it doesn't shine.