CPBD-RP-0506: Swaison's Hawk, California When it comes to deciding which lens to purchase, use, or carry, remember these points: Faster lenses are ones with lower fixed number f/stops such as f/2.8 (wider maximum aperture openings). RUNR2207: Trail running Russian Ridge, CA Slower lenses are ones with high number f/stops such as f/5.6 (the lens can't go wider than that aperture number) Faster lenses allow more light into the camera enabling the photographer to shoot faster shutter speeds. WYGT0602: Moose feeding in the Snake River, WY Slower lenses (such as zooms) sometimes have variable f/stops such as f/4-5.6 (the lens lowest aperture setting changes depending on the lens length) changing the exposure or shutter speed. Faster lenses have a wider aperture enabling the photographer to shoot with minimal depth-of-field. UTCL0318: Horseshoe Canyon Tyrolean traverse, Utah Slower lens are more affordable and usually lighter to carry. Faster lenses are usually more expensive & possibly heavier. CANC-JN-0407: Thistle at sunset, California coast There are so many lens to choose from, and the prices range drastically. Research various lens reviews in magazines and online, and ask the opinion of your local camera store rep as well. Personally, I recommend shooting with the lens you are most comfortable with, can afford, and are willing to carry- at least now, you can understand the differences.