Filter choice

Rob wrote:
Further to the recent 'Exposure' thread (and thanks everyone!) I've
tried a couple of filters - UV and polarising. I got the UV just to
protect the lens. The brand is Camlink, both 72mm filters 20UKP - so
cheap as these things go. The boxes are next to useless because the
filters rattle around, and the UV filter had blobs of grease on the
surface - so QC not a major concern. The filters themselves look OK.

The polarising filter seems very interesting, and I'll doubtless have
plenty of experimentation ahead. However, at maximum zoom (on an
18-200mm Canon lens) the focus is very poor. Could this be down to the
filter quality? Or polarising?

Thing is, I have little idea what I'm paying for here, and the range of
prices seems vast - I was going to get a 52mm polarising filter for my
other lenses.

Is there any preference? Hoya seem a good price compromise. Or should I
just stick to Camlink?

Thanks, Rob


Your comment that focus is poor leads me to wonder whether this is a
circular or a linear polarizer? As a general rule, a linear polarizer
will usually cause problems with autofocus, and circular polarizers are
generally recommended for autofocus cameras.

As far as brand and quality, only you can decide what's important to
you. It always boils down to trading off cost against performance. For
experimenting, surely an 'el cheapo' (circular) polarizer is OK. If you
decide you like what it does, then you can keep using it if you're
satisfied with the results, or step up to a higher grade. In a very
general way, quality is indicated by price. The best ones are ground
like lens elements, and have very sophisticated anti-glare coating
systems. And they cost a bundle. Even within a brand, such as Hoya,
they have both a consumer line and a pro line, so brand alone isn't an
indicator.