Understand your camera  Make, lens mount  Size of digital image sensor (full frame 35mm vs. most DSLRs about 30% smaller)

Understand types of lenses  Categories of lenses 1) entry level lenses, kit lenses, 2) good amateur lenses, 3)professional lenses  Fixed or primary & zoom lenses  Wide angle, Normal, Telephoto  Optional Lens functions- auto focus, vibration control, macro

What impacts cost?  Quality of lens, glass, coatings  Quality of barrel, mechanism holding glass in place  Speed of lens, f-stop, fast lens, options

Understand type of photography you will be doing  sports  portraits  landscapes  interiors  general, all of above  macro  fish eye

Best bet for the amateur photographer Consider -  Camera manufacture vs. third party lens  Single lens zoom from WA to Telephoto  Speed of Lens f-stop  How much can you afford to pay?  Added weight to camera