In Reply to: Extension tube question posted by Elaine on December 13, 2005 at 22:16:26:

With the tubes set at infinity, I never noticed an improvement in
depth of field, but since depth of field is determined by
magnification ratio, and there's a very slight decrease in mag,
there should be a very slight increase in depth of field.

Setting the lens at infinity was mostly useful for critters that
were a little shy of the framer, or were very slightly back in
a hole.

Off to go diving now.

Chuck