In article <4ph7ps$fup@nwd2nws1.analog.com>, sgold@.adsdesign.analog.com says...

>Any thoughts on the wisdom or lack thereof of using one of the Nikon
>closeup lenses on the 105mm 2.8 Micro-Nikkor? I'm not necessarily
>after more magnification, but mainly seek greater working distance
>so as not to spook butterflies and dragon flies.

This is unlikely to work for you (though the Nikkor "T" achromats
can provide excellent sharpness with many lenses), since close-up
lenses work by shortening the lens focal-length without changing
the barrel length, hence the closer focus. Try a 1.4X (or 2X, if
your light source is flash, allowing the small apertures needed
for excellent sharpness) converter for more front space with the
same magnification. BTW, under some conditions, butterflies and
dragonflies seem totally unaware of the photographer's presence,
no matter how close the lens (seems to happen if you can get one
flash exposure before the insect disappears - after that, anything
is possible [I have some nice dragonfly head pictures....]).
Hope This Helps