What's the difference between Nikon AF and Nikon AF-D

There are a bunch of Nikkor 105mm Macro (Yeah, Nikon calls them "Micro")
lenses out there which just say "AF" on the barrel and others which say
"AF-D". What will a -D lens do that the AF won't?

TIA
Norm

 

D lens relays distance information to the camera to be used in calculating
flash duration so as to ensure proper illumination of the subject.

 

Does anyone have a good explanation why that matters? In my mind, reflected
light is reflected light. Whether it comes from a short or a long
distance.

Before Nikon came up with D lenses, distance information hardly ever came
up in exposure computations (the only exception I know is macro
photography).

 

Not really, but I do notice that Nikon will allow you to blow out objects
close to the camera provided they aren't at the focus distance.

 

Well, I know it's used with some flash modes to have the camera set the
aperture automatically based on the power and distance.

Also, I vaguely remember reading that some cameras -- most notably the
D50/D70 won't even attempt to do automatic exposure unless the lens is a "D"
or "G" --- is this correct?

Norm

 

Hmm, now that I think of it. Maybe that, when combining information from
the AF system with the exposure data, knowing the focal length of the lens
and the absolute distance helps in computing expected light fall of due to
distance.

However, a D1 plus an SB-28DX and of course a D lens (the only 'modern'
combination I played with) doesn't seem more accurate than for example an
FE2. And the D1 has the advantage of using pre-flashes to compute the
proper exposure.

 

That is nothing magic. Based on a pre-flash the camera computes the
required exposure and stops down the lens to an appropriate level.

Without a pre-flash (typical TTL flash for film SLRs) only the
flash duration can be used to control the power of the flash.

A D100/D70/D50 needs a cpu-lens for automatic exposures. I doubt that a D
lens would be required. But I don't know the details of the D70
flash system.

 

Okay, I've finally found the Nikon D70 camera guide and here's what is says:

Compatible Lenses
Type G or D AF All functions supported
Micro Nikkor 85mm All functions supported except autofocus and some
exposure modes
Other AF Nikkor All functions supported except 3D color matrix
metering and iTTL balanced Fill-Flash for
Digital SLR,
AI-P All functions supported except 3D color matrix
metering and iTTL balanced Fill-Flash for
Digital SLR, and autofocus
Non-CPU Can be used in mode M, but exposure meter does not
function; electronic range finder can be used
if
maximum aperture is f/5.6 or faster

SO ... I guess the Nikon 105 AF (non-D) would autofocus and could be used
in the non-matrix metering exposure modes and couldn't be used for iTTL
fill-flash with an SB-600 or SB-800

Norm