A good wide-angle lens is the backbone of landscape photography, pulling in massive vistas and starry skies without distorting the horizon. Buy a sharp piece of glass once and you won't find yourself upgrading in two years because the corners are soft or the weather sealing failed.
Timing matters just as much as the focal length. Camera makers usually refresh their lineups on predictable cycles, which means last year's flagship model often drops in price the second a newer version hits the shelves.
That 18-month window is a hard deadline, not free money, and if any part of the $800 balance is still sitting there when it ends, the standard interest rate kicks in on the whole original amount.