B&W 67mm circular polarizer glass filter $84.

[fevbusch]

  I'm thinking of buying the b&w for my Pentax 16-45 f4 lens.
   Adorama has it for a good price. Its not the top quality lens. Any comments or criticisms will be
  appreciated.    Freddy

[calsan]

Hi Freddy
I read your question before heading out today, so it reminded me to pack a polarizer in my bag!

Well, I hear B+W are the best, however I have Hoya's Pro 1 D polarizers and I'm more than happy with their quality.
The two main things with polarizers is that they:
1. be multi-coated - B+W are sure to be OK here.  [This is important to maintain the image quality of your lens.]
2. don't cause vignetting on your lens - you need to test this out yourself!

Because of this second reason I prefer to try polarizer in a 'physical shop' before buying - particularly for wide angle lenses like the 16-45.  The reason is that they can vignette at the wide settings of your lens.

I took these shots today with the 18-55 and a Hoya Pro 1D.  I 'tuned' the polarizer to make the sky as dark as possible in the Post Office shot.  The shot of the water shows that a good polarizer won't cause flare against the light.  The tree shot shows the polariser at maximum effect and then rotated to minimum effect.
Cheers!
Cal   

[Mike Pearson]

Very good examples Cal - I just checked my circular polarizer and it is a Hoya "Super Quality" 67mm.

Package says "it has seven layers of multicoating applied to the rear surface to eliminate image ghosting. This is a low profile (just 5mm) making it ideal for use with wide-angle zoom lenses."

So far I've had absolutely no problems with mine on the 16-45.

Mike

[fevbusch]

Mike, I got just the answer I wanted.  Someone who has the 16-45 (you) and says
  he doesn't have any problems with it.
  So, I'm buying the $94. thin super quality multi coated 67mm hoya that you have.
  Just want to see if I can get it cheaper then $94.   Have to shop around.
   P.S.  Don't worry, I KNOW you're not guaranteeing the lens.  Who knows, what works on one
 camera might not work on another.
      Thanks for your help.    Freddy

[Mike Pearson]

Freddy - I forgot to mention that like anything else good it is expensive - hey but well worth it 

Mike

[calsan]

Freddy - I forgot to mention that like anything else good it is expensive - hey but well worth it 

Mike

2nd this - I paid more for my polariser than the lens in the examples above.  Always have to laugh when I see $5 polarisers listed on ebay being supposedly for the FA31 limited.  What a disaster to combine a cheap polariser with the best lens!!!

[Ron Kruger]

I have both Hoya Pro 1D and BW polorizers. They both seem to be fine for mid-range CPs, though Hoya may be slightly better. Since they own Pentax, I suspect their filters are a better match for Pentax lenses, though I'm just guessing.
The first Hoya I bought was for the 18-55 kit lens. Like Calsan, I bought it to improve the optics, and like him, I think one of the dumbest things someone can do is screw a cheap piece of glass in front of a good lens. I don't use the kit lens anymore, but the Hoya fits on one of my regular lenses.
You do get what you pay for. I wish I could afford even better polorizers and a Lee GND kit. Some day...