Should I use a lens filter?

[tanneuby]

I am going to be shooting some motorcyle racing next weekend with my 10D and EF70-200 F/4. Should I use any kind of filter? If so, what kind if its sunny or cloudy?

[scollins]

I always have a UV/haze filter on my lens, but sometimes use a circ. pol. if I'm doing a lot of outside work in the sun. It does slow you down by about two stops though.

[tanneuby]

Sorry, I'm new, but what is a "circ. pol"?

[UrbanScribe]

circular polarizer. "Polarizers let you deepen and intensify blue skies, achieve vibrant color saturation, reduce or eliminate glare and reflections from non-metallic objects and glass surfaces, and minimize haze in both color and black-and-white photography. They can be rotated to determine the amount of reflection to be removed. Rotate the polarizer to change blue sky densities from light to dark blue. Create dramatic contrast between blue skies and white clouds.

Standard linear polarizers are used with many cameras, while the circular polarizer is used on cameras with beam splitting metering systems commonly found on automatic SLR and autofocus cameras. Check your camera manual for the metering system employed. A circular polarizer can be effectively used with all cameras.

You can, in all cases, see the effect through the filter. If you are not using an automatic camera or have you camera on manual setting, both filters require that you open the lens from 11/2 to 2 f-stops."

[Vegas Poboy]

My general rule of thumb is always keep a UV filter on my lens due to me sometimes being clumsy. It has save my lens more than once from dings, scracthes and dirt. Second I always carry a Circular Polarizer filter due to the bright daylight here in Las Vegas, it really helps with cutting out glare of reflective objects and increases detail. Best way to think about it is you're putting sunshades on your lens. When I shoot drag racing @ night just the UV fliter.