UV, Haze, or Skylight?
Those who have read my other tips know I'm not a fan of using so called "protective" filters unless there is an overriding reason to do so such as when shooting around blowing sand or salt water. When you do decide to use one though, what kind should it be, UV, Haze filter, or Skylight? Or perhaps something else?
The truth is, for most subjects and nature in particular, it really doesn't matter. There is more variation in color palettes between various film emulsions than there is between a UV filter, Haze filter and a Skylight filter. All of these have a very slight warming component which can actually benefit most outdoor subjects. Which ever you choose though, be sure it is a multi-coated filter to cut down on flare and keep light transmission to a maximum.
For the ultimate in color accuracy, Nikon and many other manufacturers make an "NC" or "no color" filter that is simply clear glass with multi-coatings.
If you are shooting digitally, it matters even less which of these you choose since the white balance is completely user adjustable in the camera.