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| Date: |
1-25-2003 |
| Price: |
paid
$100, normal price is closer to $150 |
| Design: |
2
inch Crayford focuser |
| Description: |
High
quality focuser for refractor telescopes. |
Review
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
that
ship with Synta refractors leave a bit to be desired (to put it
mildly),
and I've been looking for a while now for a decent diagonal.
However,
spending money does not necessarily get you a good diagonal. Over
time
I've separately bought a TeleVue (1.25", $75) and a Lumicon
LumiBright
(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
construction than
my other diagonals (so I guess money does buy you something).
Well,
good news: the William Optics diagonal is superb!
In addition to the 1/10-wave mirror (which I am not in a position
to
verify, but unlike the other brands WO puts 1/10-wave in their
advertising), the construction is very solid, unusually
attractive, and
allows easy access to the mirror. Inside, the mirror lies flat
against
the metal housing (full contact over the entire mirror back, not
just at
the rim), and it's held in place by rubber tubing on the
shorter-length
edges and foam rubber on the longer edges. Thoughtful design.
What's more, there is no glue or adhesive; the mirror is kept
firmly in
place without the need for such crude tactics. This makes this
diagonal
eminently suitable for easy shimming, should the need arise to
adjust
its alignment. However, I'm happy to report that I doubt the need
would
normally arise. I made measurements with my laser collimator by
drawing
spots on the wall across the house. (I also have a Burgess
focuser,
which is superbly machined, very well collimated, and rock solid.
The
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
excellent,
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
worse.) My
Synta diagonal was a degree and a quarter off. I also have an
INTES
1.25" Herschel wedge, and for grins I measured its alignment:
7.2 arcmin
-- also excellent, in line with INTES's reputation.
Finally -- as if the WO diagonal was not already a great deal --
it came
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
threaded
for filters. All interior metal surfaces are painted flat black.
Also,
both diagonal and adapter use compression rings to hold your
eyepieces
-- yet another plus. Thus, in summary, the William Optics 2"
diagonal
is superbly constructed, very well aligned, and an absolute steal
at
$100-$150. Go buy one now. Really! |
Submitted by Marc A. Murison - Wheaton, MD
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