Just for my info, are you saying the G lens has aperture blades that the F5 or F6 can control somehow?
Yes. F100 too, and some other bodies.
Jim MacKenzie - Regina, Saskatchewan, Canada
A bunch of Nikons; Feds, Zorkis and a Kiev; Pentax 67-II (inherited from my deceased father-in-law); Bronica SQ-A; and a nice Shen Hao 4x5 field camera with 3 decent lenses that needs to be taken outside more. Oh, and as of mid-2012, one of those bodies we don't talk about here.
I wouldn't buy a "G" lens unless it was very cheap or free. G is not a feature, G is a handicap. G lenses are crippled lenses without aperture rings and completely useless for manual photography. If it wouldn't work on my FM3a it isn't worth buying.
G lenses won't work on the FM3a but they work very well indeed for manual photography. With the camera like the F5 (and many others) you can manually set the aperture in 1/3 stop increment. Much better than the aperture ring.
If you argue that the F5 is an automatic camera then the FM3a is also an automatic camera it's not a manual only camera like the FM or FM2 for example.
In fact I found that the F5 is an excellent camera for manual photography although it's matrix mettering mode left a lot to be desired in auto exposure mode. I can set both shutter speed and aperture manually in 1/3 stop increment and with only 1 hand.
Sometimes you don't get much choice, I wanted a 90 or 100 ish macro lens that went to 1:1 all by itself. ALL new lenses that do this, from Nikon or other manufacturors, are 'G' type lenses, which limits me to using it on my F100. I have to use an older Tamron 90mm on my FM3a, but that only goes to 1:2 by itself. I hate lack of compatibility between models. The best compromise is being able to use it like a G type lens by locking the aperture at f32, that way you have both options, but even a second hand 105mm Nikon micro D type is beyond my reach.