The William Optics Ultra-Cat 108 is a high-end astrophotography telescope designed for those seeking top-tier imaging performance. Featuring a five-element Petzval optical system, it delivers razor-sharp, well-corrected images with exceptional color accuracy and minimal aberrations.
With a large 108mm (4.25″) aperture, this refractor collects ample light, providing high contrast and impressive detail resolution. Its Petzval design eliminates the need for an additional field flattener or backfocus calculations, ensuring that stars remain sharp edge-to-edge, even when using medium-format and full-frame cameras.
Built to the highest standards, the William Optics Ultra-Cat 108 utilizes one ED and two Super ED glass elements, which work together to eliminate coma, field curvature, and chromatic aberrations, resulting in excellent color correction and image clarity. The 60mm image circle ensures full-frame cameras can capture an expansive, distortion-free field, making this refractor a powerful tool for deep-sky imaging.
Designed for speed and efficiency, the 518mm focal length and f/4.8 focal ratio make this telescope a fast-imaging system, allowing for shorter exposure times while capturing deep-space objects in stunning detail. The big 60mm image circle supports large-format sensors, ensuring that astrophotographers can take full advantage of wide-field imaging without compromising sharpness.
Alongside its advanced optics, the William Optics Ultra-Cat 108 incorporates William Optics’ Internal Focus Design (WIFD), which replaces traditional external focusers with an internal focusing mechanism. This not only enhances stability by eliminating drawtube sag but also ensures precise and repeatable focusing, especially when using heavy imaging equipment. This feature is particularly beneficial when using heavy cameras, filter wheels, and other imaging accessories, as it maintains precise optical alignment throughout long imaging sessions. If desired, the internal focuser can be electronically controlled, further improving efficiency and imaging consistency.
With the WIFD design, the movement of the focuser is integrated inside the main tube assembly providing the benefits of a traditional two speed fine focuser, while not worrying about limitations typically found in traditional rear mounted focusers. The WIFD design includes the patented William Optics center focuser with precise internal sliding of fixed optics to prevent image shift. The integrated position viewing window on the focuser provides instant verification of the graduated numerical display. The smooth rack and pinion design is incorporated into the focuser to provide super fine adjustability for critical focus. The internal movement of the optical elements is protected from the elements and can’t come out of alignment. The redistribution of weight allows for better balance during imaging sessions.
The package includes three adapters (M68, M54, and M48), offering seamless integration with various imaging setups. Also included are mounting rings, CNC handlebar, dovetail plate, Bahtinov Mask cover and carry case.
The William Optics Ultra-Cat 108 specifications include:
– Lens Type: Petzval Design
– Focal Length: 518mm
– Aperture: 108mm
– Focal Ratio: f/4.8
– Image Circle 60mm up to Medium Format
– Flattener: 5 Element Petzval
– Focuser: WIFD Internal Focus Design, Compatible with EAF
– Lens Material: Super ED Glass x2 ED Glass x1 Lanthanum Glass x1 X-Element x1
– Camera Format Compatibility: Medium Format Full Frame APS-C M4/3
– T-Mounts Supported: Canon EF, RF, Nikon F, Z, Sony E, Pentax K, Micro Four Thirds, FUJI X
– Tube Length: 510.5-588.5mm
– OTA Weight: 17.53 lbs.
You can learn more about the William Optics Ultra-Cat 108 here.
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