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Price - $67.00

Ad Number: 249780

Posted: 26 Mar 2021

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I purchased a glass solar filter for a C90 Maksutov Cassegrain astronomical telescope, and the telescope itself, in the late 1970s to very early 80s directly from Celestron. I sold the telescope many years ago but still possess the filter. I do not precisely remember but I believe that I purchased the filter for $100. (My memory cannot guarantee that my cost is accurate.) This filter was a custom Celestron product for the original model C90. I purchased the telescope and filter shortly after Celestron introduced this as a new product. The retaining ring on the filter is metal with a small thumbscrew and two tiny recessed adjustable screws to adjust/tighten the filter to the end of a telescope tube. It appears that the two recessed screws assist in adjusting the filter to the thickness of the tube wall; as a result, the filter should fit some other 90 mm diameter telescope tubes. The thumbscrew will hold it securely in place. The filter hasn't been used in forty years and is in very good condition. There are no scratches on the glass which has a silver mirror coating. I think that this solar filter is both a useful accessory for owners of the original C90, and an ideal collectible for hobbyists who enjoy vintage items. The price includes shipping costs in the United States.


  • Condition Very Good to Excellent
  • Location Queens Village, New York

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