Baader Maxbright 2" Dielectric Mirror Diagonal
15 April 2003
UPDATE: It is now more common to find Baader's newer Clicklock diagonal - read my review here. The Clicklock eyepiece holder used on that diagonal can in fact be used on the Maxbright - ask your dealer for details.
Baader Planetarium has a long history of designing and manufacturing dielectric (enhanced) mirror diagonals. In addition to their older Maxbright diagonals, they designed and manufactured Astro-Physics' dielectric diagonals until recently. AP may have terminated their diagonal relationship with Baader a little too soon. Last year Baader started searching for a way to improve the one weakness of dielectric mirrors - the coating process warps the substrate producing noticeable wave front error. In fact, other dielectric mirrors often perform worse than 1/4 lambda - the threshold most consider produces visual errors.
Baader's goal was to produce a dielectric mirror with a wave front error of better than 1/10 lambda. The result is the new Baader Maxbright 2" diagonal. UPDATE: Baader is now producing a 1.25" Maxbright diagonal which they call the T-2 Maxbright diagonal. It uses an oversized body similar to this 2" diagonal and the same high-quality dielectric mirror surface. The oversized body allows interchangeable barrels - even 2" barrels for use in 2" focusers and to allow use of 2" eyepieces. But still, the mirror is just a bit larger than a standard 1.25" diagonal and you do not get the same aperture as a 2" diagonal. That said, it is the premier 1.25" diagonal on the market.
Baader achieved this high level of near-perfection with a patented process involving more than 50 layers of dielectric coatings on both sides of the mirror substrate. Naturally, the back of the mirror doesn't actually reflect anything, but Baader discovered coating both sides kept the mirror perfectly flat. And, the dielectric coatings, as in all similar mirrors, offer extremely high reflectivity (98.5% in the case of the Maxbright) and are nearly impervious to scratches. Additionally, dielectric mirrors do not corrode, even in the most humid, salt-air conditions. This allows the mirror to be cleaned with no fear of damage while producing the brightest possible images for the life of the owner.
The fit and finish of the diagonal and other accessories I will discuss is superb. All parts are machined and fully anodized or chromed. All thumbscrews are oversized (two for each connection) and actuate brass compression rings that provide a superior grip on eyepiece, barlow and adapter barrels while protecting them from the thumbscrews themselves. The threading in the body of the diagonal, for the barrel and eyepiece holder, is very deep, eliminating the possibility of stripping the threads as commonly occurs on budget diagonals. The entire assembly is absolutely solid.
Optically, the diagonal is perfect. This is comparing the image with the diagonal to the image without the diagonal (eyepiece directly in the visual back). Considering you want the diagonal to be optically invisible, I don't know a better way to test it. Mechanically, as I mentioned above it is built like a tank. And I'll report back in 50 years or so on the durability of the mirror itself :-)
The only potential drawback is price. The Maxbright is not yet commonly available outside of Europe, but I estimate the price of just the diagonal to be about $400 US (cost will vary with the Euro/US Dollar exchange rate). If you are interested in owning the last diagonal you will ever need, in North America you should contact Alpine Astronomical (www.alpineastro.com). Alpine also carries most Baader T-2 system adapters. In Europe, all products are available directly from Baader Planetarium (www.baader-planetarium.de). Follow this link (once there select German to English from the "Translate a Web page" list and click the "Translate" button) for a translation of the page on Baader's site.
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