William Optics Cat Mounting Ring

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50mm Inner Diameter Solid Aluminum Construction Anodized Blue Finish 1/4"-20 Threaded Mounting Holes Weight: 4.9 oz (140 g) Description FAQ Specifications In the Box Warranty Willi am Optics Cat Mounting Ring The William Optics Cat Mounting Ring is a secure, custom-fit mounting point for telescope tubes with a precise 50mm outer diameter. Machined from solid aluminum and weighing just 4.9 oz (140 g), it adds minimal weight while offering standard 1/4"-20 threaded holes for attaching to dovetail bars or other accessories. Precision-Machined for a 50mm Tube Diameter This is not a one-size-fits-most solution. The William Optics Cat ring is engineered for an exact 50mm tube diameter, ensuring a rigid, non-slip connection without marring your telescope's finish. The solid aluminum construction prevents the flexure that can ruin a long exposure when using the ring for a guide scope. Because the fit is so precise, you must verify your telescope's dimensions before purchasing. These rings are manufactured with zero tolerance for tubes larger than 50mm—even a 1mm difference will prevent a fit. We strongly advise using calipers to measure your optical tube directly rather than relying on published specifications, which can change between production runs. Solid Aluminum Construction: Machined from a single block for maximum rigidity and zero flexure, weighing only 4.9 oz (140 g). 50mm Inner Diameter: Designed for a perfect, non-marring fit on telescope tubes with an exact 50mm outer diameter. Anodized Blue Finish: Provides a durable, corrosion-resistant surface that matches William Optics' distinctive aesthetic. 1/4"-20 Mounting Holes: Offers standard threading for secure attachment to Vixen or Losmandy style dovetail plates. Will the William Optics Cat Mounting Ring fit my telescope? This ring is designed exclusively for any optical tube with an exact 50mm outer diameter. Because manufacturer specifications can change without notice, you must physically measure your telescope's tube with calipers to confirm the size before purchasing. Do not rely on published specs alone. My telescope tube is 51mm. Can I make the William Optics 50mm ring fit? Absolutely not. The ring has a precise 50mm inner diameter with no tolerance for larger tubes. Attempting to force it onto a 51mm tube will damage the ring, your telescope's finish, or both. You must have an exact 50mm tube for this ring to fit correctly. Is the William Optics Cat Mounting Ring sold as a single unit or a pair? The William Optics Cat Mounting Ring is sold as a single unit. If you need a pair to mount a longer optical tube or a guide scope, you will need to purchase a quantity of two. I'm building a custom guide scope setup with a 50mm finder. Is this William Optics ring a good choice? Yes, this is an excellent application. The ring's solid aluminum build provides a rigid, flex-free platform for a 50mm guide scope, ensuring there is no differential flexure between your main telescope and your autoguiding system during an imaging session. What are the mounting holes on the William Optics Cat ring for? The ring features standard 1/4"-20 threaded holes. This is the most common thread size in photography and astronomy, allowing you to attach the ring securely to most Vixen-style or Losmandy-style dovetail plates, as well as other astronomical accessories. What is the William Optics Cat Mounting Ring made of? It is machined from a single piece of solid aluminum and features a durable, anodized blue finish. This construction ensures it is both lightweight at just 4.9 oz (140 g) and extremely rigid. SKU WO-M-MR50RC-BL Inner Diameter 50mm Material Solid Aluminum Finish Anodized Blue Mounting Holes 1/4"-20 Threaded Weight 4.9 oz (140 g) 50mm Cat Mounting Ring × 1 William Optics 2-Year Warranty Show more