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Astro-Physics MaxBright Diagonal

5.0 (1 Reviews) Read Reviews Write Review
Brand Astro-Physics
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2" MaxBright diagonal with 99% dielectric coatings


5.0 (Based on 1 Reviews) 100% of reviewers recommended this product.
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    1. nam2525

      nam2525 New Member

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      May 2, 2007

      5.0 Regarded as the BEST you can get...but at a BIG price


      Extremely high quality, durable.


      Very high price.


      This 2 inch diagonal is critically acclaimed as the best diagonal available. However, it also costs about $300!!! The website says it has 52 layers of dielectric coatings, which are more durable than any type of metal coating. Light transmission is above 99% over the entire photo and visual range of light. These coatings also provide a 5-fold reduction of scattered light when compared to other coatings. It has a machined aluminum housing for rigid construction. The person at Astro-Physics who tests these diagonals (and is also known for his world-renowned telescopes) says the goal is to get the surface flatness (for any part that will form an image of a star anywhere in the field of view....not necessarily "total" surface flatness) to between 1/40 wave and 1/20 wave, with 1/20 being the lower limit. The material for the mirror is low-expansion material. When I bought mine 2 years ago, it came with end caps but NO 2 inch-to-1-1/4 inch adapter (for $300 you think they would have included one!!)

      Did I mention it costs $300!!! There are other dielectric diagonals that offer 1/10 wave surface flatness and about 40 layers of coatings...this should also get the job done and be just as durable as the MaxBright, AND these other diagonals usually cost far less. Their housing, however, may or may not be as strong as the Maxbright....check reviews to see what others are saying about the GSO and similar diagonals.

      The MaxBright can best be described as adding no defects to the system. It just disappears in use. As for the light transmission, they say the human eye can detect a difference of 9% or more....so in theory the diagonals that give 97% or 95% transmission with metal coatings should seem just as bright as the MaxBright....the main difference would be that dielectric coatings are far more durable and resistant to scratching! For this reason, if you plan on using a diagonal frequently or in harsh conditions, or if you think you will need to clean it often because of heavy use, then give strong consideration to a dielectric diagonal (any brand) for more peace of mind.

      In summary, if you want the best 2 inch dielectric diagonal available, get the MaxBright. If you want a diagonal that should be pretty close in terms of performance but is easier on the budget, consider some of the import dielectrics after checking reviews on them.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No
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