JoeM845

@amfoto1 makes a good point about the polarizing effect being greatest when looking 90 at a 90 degree angle from the sun. The least effect is when looking 180 degrees from the sun (also 0 degrees). A 10mm lens has about a 100 degree field of view (wide dimension) when used with an APS-C sensor. That means you can compose a picture with sky ranging from 90 degrees from the sun (maximum effect) to 180 degrees (minimum effect) giving a very obvious darkening in only part of the sky. I suggest that you play with the combination BEFORE you start your trip to experience the variation. You will be able to see it when you shoot in the Park but you might forget to pay attention with the Park's grandeur in your sights.

Also, a polarizer can give you much richer foliage colors.

Salo Loc: Cherry Hill, NJ

With all the wildlife and other beautiful natural objects you will witness in RMNP, you shouldn't leave your wide to telephoto Sigma at home. I guarantee​ you will wish you had its long reach with you. It's an excellent lens as well. You will also use the CP quite a lot especially if you have beautiful sunny days. I'm not sure you will want to lug a tripod around, and there are improvisational ways to stabilize your camera if absolutely necessary. Have a great trip and show us your photos when you get back.

twowindsbear

How are the answers to this question all that different from the answers you received when you asked the same question about 3 lenses in this post??

http://www.uglyhedgehog.com/t-456056-1.html

illininitt

two: I sold the 17-50 on Ebay. I'm now asking about 2 lenses....not 3! If I but another lens down the road....I will ask again adding the NEW lens!
It's like asking who's a better band: Dave Clark Five-Kinks or Manfred Mann. You elimnate Manfred Mann and ask the same question between DC5 and Kinks. Then down the road you add Gerry & the Pacemakers and ask who is a betterband Dc5-Kinks or Gerry & the Pacemakers. Every time you add/subtract.....you ask again between those 2/3!