Last updated: 10 February 2006
Subject: Lumicon Diagonal Sent: Thursday, February 9, 2006 21:23:50 From: The Brown Family (email@example.com) 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! Regards, Chris Brown
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