I've got some lens questions. I'm familiar with the Nikkor AI or AIS lenses but I'm clueless when it comes to AF. I've seen "D", "G", etc. lenses on eBay. I'm thinking each different letter denotes some type of quality or lack of? Will any Nikon AF lens work and meter with a D70? I know the older AI or AIS will work but the metering won't. Any help would be appreciated!