Help choosing a camera lens?
I have a nikon d5100 and have two lenses for it. I have a 18-52mm kit lens and a 70-300mm lens. What lens should I get next that I'll get the most use out of (I mostly photograph landscapes by the way)
A great lens for landscapes is an ultra-wide zoom.
I have a Sigma 10-20 f/4-5.6.It is SUPERB!
Tokina 12-28 F4 would be my pick. Depends on your budget really. The Sigma 10-20mm (in any iteration) is a good deal too.
PS. I wouldn't use a polariser on a wide angle lens.
Although the 18mm end of your 18-55mm zoom lens is adequate for landscapes, you might consider the AF-S DX NIKKOR 10-24mm f3.5-4.5G ED for your landscape photography. Sigma also offers a 10-20mm f4-5.6 EX DC HSM wide angle as well as a constant aperture version, the 10-20mm f3.5 EX DC HSM.
For the best landscapes I consider a tripod as mandatory.
Landscapes are best shot with a wide angle lens. Look for one that's shorter than 18mm. If you go lower than 12mm, that's already fisheye and the distortion it will produce won't be good for landscapes.
For landscapes, the Sigma 8-16mm, Nikon 10-24mm, or Tokina 11-16mm would all be good choices.
The 18mm end of your 18-55mm is excellent for landscapes - worry when you can't do what you want with that.
I use the Sigma 10-20mm - it is an excellent lens. Even better is the Tokina 11-16mm.