lens - AF-D vs AF-G: is the aperture ring necessary?

I just purchased a Nikon D7000 with an 18-105 f/3.5-5.6 AF-S lens. I'm also looking at purchasing a lens around the 200-300mm focal length range, and I found the 70-300mm f/4-5.6 AF lens. As far as I know (and I'm completely new to DSLR photography, so bear with my lack of proper terminology), my D7000 can autofocus with this lens as the body has an autofocus motor.

I've seen two different models of this particular lens: AF-D and AF-G. It seems as though the AF-D is a lot harder to find and more expensive than the G because of the G's lack of a physical aperture adjustment ring. I haven't quite become accustomed to the controls on the camera, so I've found myself manually adjusting the aperture a few times. However, from what I've read (and I would assume this is the case), it's possible to adjust it with one of the two dials on the camera.

I'm just wondering whether it's worth spending the extra money on the AF-D, or if the AF-G will provide me the same quality pictures and will have the same functionality for a lower price. (I'm on a student's budget, so price is quite important to me).

Thanks, and greetings from SU!

Answer

In most cases, the "G" lenses are newer designs that perform better than the older, "D" varieties (all other things being equal -- like the max aperture, etc.). They tend to have better lens coatings, better use of low dispersion, anomalous dispersion and aspherical elements, and more rounded apertures (which provide better bokeh). For use on DSLRs, the "D" lenses only have an advantage when you "freelens" or use the lens reverse-mounted or on a "dumb" tube for macro work, since there's no easy way to control the aperture on a "G" lens when it's not electrically connected to the camera.

"D" lenses, though, can be used on older, non-AF film cameras, where using manual exposure (or aperture-priority AE) means using the aperture ring -- there's no control over the aperture setting on the camera body other than what comes from the AE system in Auto, Program or shutter-priority mode.

If you have no plans to use an older Nikon film body, then the "G" lens is the way to go, particularly if the price differential is in your favour. But check the reputable reviewers before opting for "cheap for cheap's sake" -- there may be a very good reason why one particular lens is more expensive than another.