Re: Close up rings for D70 Do you mean diopter supplementary lenses that fit on the front
of a lense like a filter? Or do you mean extension tubes?
Both will work. With extension tubes though you need to make
sure that you get a modern design intended for cameras/lenses
with auto focus. The older ones do not couple the electrical
contacts from the lense to the camera, which means "manual
mode". (Your G lense won't work in manual mode at all. Also
the D70's light meter doesn't work in manual mode.)
The lenses will work, but... Lense designers make lots of
compromises, and generally there is a reason for the limit on
how close a lense can focus, as that might be where sharpness
begins to suffer. Likewise "macro" work often, but not always,
requires "flat field" optimization, and regular lenses trade
lower astigmatism at infinity for more curvature of field at
closer distances. For images that require a flat field you'll
definitely want a "macro lense" that actually is optimized at
short focusing distances. For pictures of flowers, you won't
need a flat field lense, but for pictures of stamps you will.
Zoom lenses are less likely to be sharp at closer distances.
Without knowing better I'd bet the 50mm f1.8 would work better
than the 70-300G.
Another interesting thing is that telextenders work fairly well
with close focusing lenses. Hence a 2x telextender on a 90 or
105 mm macro lense in general makes a fairly good ~200 mm
macro lense (compared, for example to using extension tubes on
an average 70-210mm zoom lense). I would assume that a 2x
telextender and extension tubes with the 50mm lense would be
more useful than the 70-300mm zoom with extension tubes (but
only testing them will tell you if that is true).
Supplementary closeup lenses (diopters) will "work" on just
about any lense. They have less effect on shorter focal length
lenses than on longer ones, so the effect using the 50mm f/1.8
lense is hardly worth it unless you use a very strong one. Also
there are two kinds of diopters. The inexpensive ones are not
that great, and suffer from chromatic aberrations (focusing
different colors at different places, thus causing color
fringing for example). The good ones use two lenses instead of
one, and are much better performers, but they cost significantly
more too.
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
Floyd@apaflo.com (Floyd L. Davidson)
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