Sky and Telescope
$100, normal price is closer to $150
inch Crayford focuser
quality focuser for refractor telescopes.
|I recently got a William
Optics 2" diagonal from Anacortes (marked down
to $100 from it's normal $150). It's well known that the diagonals
ship with Synta refractors leave a bit to be desired (to put it
and I've been looking for a while now for a decent diagonal.
spending money does not necessarily get you a good diagonal. Over
I've separately bought a TeleVue (1.25", $75) and a Lumicon
(1.25", $150). Both were badly misaligned, though not as
badly as the
one that came with my Chinese refractor. I was able to shim the
LumiBright into decent alignment due to better housing
my other diagonals (so I guess money does buy you something).
good news: the William Optics diagonal is superb!
In addition to the 1/10-wave mirror (which I am not in a position
verify, but unlike the other brands WO puts 1/10-wave in their
advertising), the construction is very solid, unusually
allows easy access to the mirror. Inside, the mirror lies flat
the metal housing (full contact over the entire mirror back, not
the rim), and it's held in place by rubber tubing on the
edges and foam rubber on the longer edges. Thoughtful design.
What's more, there is no glue or adhesive; the mirror is kept
place without the need for such crude tactics. This makes this
eminently suitable for easy shimming, should the need arise to
its alignment. However, I'm happy to report that I doubt the need
normally arise. I made measurements with my laser collimator by
spots on the wall across the house. (I also have a Burgess
which is superbly machined, very well collimated, and rock solid.
6" Synta refractor was clamped in place on a worktable.) The
WO 2" I
received is only 5.4 arcminutes out of alignment. This is
especially for diagonals this price range. Contrast that with the
LumiBright *after* a couple of hours of frustrating shimming and
adjustment: 15 arcmin. (It was originally about three times
Synta diagonal was a degree and a quarter off. I also have an
1.25" Herschel wedge, and for grins I measured its alignment:
-- also excellent, in line with INTES's reputation.
Finally -- as if the WO diagonal was not already a great deal --
with a 2"-to-1.25" adapter which has the same
high-quality machining as
the diagonal housing. Both the diagonal and the adapter(!) are
for filters. All interior metal surfaces are painted flat black.
both diagonal and adapter use compression rings to hold your
-- yet another plus. Thus, in summary, the William Optics 2"
is superbly constructed, very well aligned, and an absolute steal
$100-$150. Go buy one now. Really!
Submitted by Marc A. Murison - Wheaton, MD