I am looking to get a couple of lenses in the very near future to go on a Maxxum 7D. I know that you get what you pay for, but for use in the desert what would you folks recommend, keeping in mind that I don't plan on spending a hugh amount of money on these lenses to be used here. I have seen the following manufacturers and would like anyone/everyone's opinion on them. Sigma, Tamron, Phoenix, vivitar, Tokina, and of course Konica Minolta. Thanks in advance for all the great advice I'll receive.