[Francis]

Can you share EXIF on the latest one?

[Class A]

Is your polariser a "linear polariser"? They can interfere with the metering and the AF (auto focus). Make sure you are using a "circular polarising filter".

Very good polarising filters are made by Hoya and B+W.

BTW, you don't need a polariser unless you want to reduce glare from foliage and/or want more saturated colours. A polariser will eat some light and for sports I'd take it off unless you have more than sufficient light.

For protection you can get a UV filter or a clear glass protection filter. Opinions differ about the necessity for such protection filters. In normal circumstances they are not needed. If you are shooting in adverse conditions, it can be comforting to know that if you should catch a sand particle while cleaning the lens, you are only putting the filter in danger.

[Ivan Glisin]

Guys, I figured it out.... to protect my lens, I bought a clear glass polarized screw in.

You probably meant UV filter? There is no clear glass polarizer.

any recommendations on which protector to buy.... too bad cause i spent like 60 bucks on this junk

To my experience, do not buy any "protector" UV filter. No matter how good they are you may expect some image quality degradation, which is especially magnified with long focal lengths as you have already experienced. Just keep the lens hood always mounted to avoid banging the front elements against something hard and you'll be fine.

[rfortson]

Whether or not to use a UV filter is an old debate. Your experience is one reason people cite for not using them. Many people use them with no problem though so I can be done.

Personally, I rely on the lens hood for protecting my front element.

For your son's baseball games, try AF-C and set the camera to only release the shutter when focus is achieved. You might miss some "moments", but the shots should be in focus. Once you're confident you can reliably get shots in focus, then you can move on to timing the "moments".

Like you said, Nikon may be a little better at AF, but the Pentax gear you have should easily capture your son's games. I shoot my daughter's soccer with the K20D (and now the K5) and DA*200 and I've gotten some amazingly sharp shots. So I know Pentax is up to it. I do occasionally miss some shots, but I get plenty that are very nice.

[excanonfd]

When shooting your son's activity with your long zoom lens, set the shutter speed to 1/250 sec or higher, set the aperture to f8.0 and let the camera decide the ISO setting. High shutter speed in sports photography is a must because you are trying to freeze your son's movement and also compensate for your movement of tracking your son with the camera. Set the aperture to f8.0 or smaller is to maximize the depth of field. In your shot of your son trying to catch the ball, his torso is behind his glove and the ball - shooting at smaller aperture could potentially allow you to capture a sharp image of your son and the ball. K-5 is more than capable in handling high ISO, so don't be afraid to set the ISO to 6400 and higher.

Hope this helps,

[Ofer Hadas]

I have Hoya HMC for all my lenses, 2 points:
1. For some reason the filters are not “clean” straight from the box. I noticed degradation in contrast and focus when using them if not cleaned with a lens cleaning cleanser.
2. Using polarizer “cost” about 2 steps in speed or f stop

[bymy141]

any recommendations on which protector to buy.... too bad cause i spent like 60 bucks on this junk

Have a look at this UV filter test:

UV filters test - Introduction - Lenstip.com
The basics: only buy a good filter, and: a good filter is expensive,

Cheers, Bert