Last updated: 10 February 2006
Subject:	Lumicon Diagonal
Sent:	Thursday, February 9, 2006 21:23:50
From:	The Brown Family (
Lumicon Enhanced Diagonal.

In the interest of improving my ETX-90 M's deep-sky performance, I
recently bought this diagonal, along with the necessary adaptor to fit
it to the telescope's rear port.

This is Lumicon's Enhanced mirror diagonal, which boasts 96-97%
reflectivity and 1/10 wave optics for just $99.95 (!) plus S&H . I
blocked the top port with a plastic plug, after bunching some black
velvet material underneath, to block stray light. It was time to judge
not only the diagonal, but also Meade's flip mirror system! I simply
swapped eyepieces from top to rear port, flipped the mirror, focused,
and compared...

My first target was the Moon's famous crater, Plato, just 3 days from
the second quarter. Using Vixen flat-top Orthos, in 9mm and 7mm form
(138.8x and 178.5x respectively) the central craterlet and one side
craterlet inside Plato were pretty obvious, the "cave" also showed
excellent contrast with both mirrors, but I had real trouble telling the
difference between diagonals. The quality of the images were identical,
but I did notice a slightly brighter image at higher power with the
Lumicon. Next was the Orion Nebula, and this was where the Lumicon
really shined. Using a Celestron 15mm Axiom eyepiece (83.3x), the nebula
was much better defined and obvious using the Lumicon, and averted
vision stars in the area became direct vision! The wind began picking
up, so I had to end the test early.

It is obvious to me that a good diagonal can really make a difference,
even with just 90mm's of aperture, but to be fair, Meade's flip mirror
showed exceptional performance, considering it bounces a bigger circle
of light, and it has to flip! Also, 5 years of nearly constant use has
surely taken it's toll on my flip mirror's coatings.

In summary, I'm satisfied with the performance of the Lumicon diagonal,
despite the price. It must be noted that I have been known to go to
extreme lengths to extract a little extra light-gathering ability from
my little ETX (see my other submissions on this sight!) and to me, the
Lumicon seemed to complement Meade's already excellent optics!

I do have a new respect for the Meade flip-mirror, however, and under
most conditions (and budgets), it does a fine job!

Chris Brown 

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