In article <5fiv90$kcj@nntp5.u.washington.edu>, aalto@u.washington.edu says...

>I'd like to do some macro photography and am considering one of these
>three options:
>
>1) Buy a 25mm extension tube to add to my existing EF 28mm and 50mm lenses.
>2) Buy the EF 50mm 2.5 macro and a 25mm tube to get it to life size (1.0x).
>3) But the EF 50mm macro and the EF Life Size Converter.
>
>I'd like to avoid close-up diopter for obvious quality concerns.
>
>Option #1 costs $70, #2 is about $400, and #3 is about $700. All should give
>me life size macro capabilities (1.0x). Besides the convenience of having
>an all-in-one lens, what are the reasons for unloading my wallet on #2 or #3?
>(note that #3 is not an all-in-one lens anyway, since you need the converter.)

Tubes added to symmetrical-design lenses, like most f1.7/1.8/2 50/55mm
"normal" lenses can work quite well (stopped well down), but much less
well on wides and teles. Most current macro lenses incorporate moving-
element designs to keep performance reasonably well optimised over a
very wide range of focus distances (lenses without "floating elements"
are optimal at only one focus distance [though performance with many of
them does not suffer enough over their normal focus range to be noticed
by most people...]). I would not discount close-up lenses - if you use
the 2-element "achromats" made by Canon, Nikon, and others on short to
medium teles (at smaller stops), the results can be excellent. BTW,
many people prefer somewhat longer than 50mm lenses for macro work
(especially around 1:1) to provide greater space between the front of
the lens and the subject (which can be MIGHTY short with a 50mm at 1:1).
Also, a narrower angle of view can simplify the background more easily
(and DOF around 1:1 is the same with all lenses at the same f-stop).
Since 90-105mm lenses are particularly easy to design, the several
off-brand macros available at reasonable prices in this range tend to
be the best offerings of the off-brand manufacturers, and good buys.
A TTL flash (on a remote TTL cord) mounted at the end of the lens,
and pointed directly at the subject, can provide a soft-looking
light source that greatly simplifies high-magnification macro work.
(BTW, adding a 25mm tube to the 28mm may not work [the focus point
may be inside your lens!;-])
Hope This Helps