JOURNAL ARTICLE

The UltraCat 76: We test the first in a new series of super-sharp "Ultra" astrographs from William Optics.

  • Published In: Sky & Telescope, 2026, v. 151, n. 6. P. 66 1 of 3

  • Database: Academic Search Ultimate 2 of 3

  • Authored By: Dyer, Alan 3 of 3

Abstract

The article focuses on the William Optics UltraCat 76, a new super-sharp astrograph introduced in 2025 that features a patented five-element Petzval optical design with premium SuperED and ED glass and a built-in field flattener. Designed for astrophotography, the UltraCat 76 delivers exceptionally small star images across full-frame sensors with minimal vignetting and a generous 50-mm illuminated field, eliminating aperture vignetting common in refractors. Unique features include the Sensor Tilt Xterminator for fine camera tilt adjustments and an internal focusing system that shifts optics within the tube to maintain image stability. While the telescope offers outstanding optical performance, especially for high-resolution full-frame cameras, it is relatively heavy for its aperture and has some practical limitations such as finicky tilt adjustments, no direct filter accommodation, and a stiff camera rotator in cold weather. [Extracted from the article]

Additional Information

  • Source:Sky & Telescope. 2026/06, Vol. 151, Issue 6, p66
  • Document Type:Article
  • Subject Area:Science
  • Publication Date:2026
  • ISSN:0037-6604
  • Accession Number:193185503
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