Farpoint 90mm Vixen Dovetail Rings with Dovetail

Product Overview

The Farpoint FVDR90 is a complete ring set: two 90mm inside-diameter rings with 3-point adjustment, pre-mounted on an 8″ V-size (Vixen-style) dovetail bar. The tube clamps in the rings and the bar drops into a Vixen saddle. Made in the USA, with a published weight of 1.563 lb for the assembly.

Who It's For

This is a good match if you have an optical tube or guide scope up to 80mm in outside diameter and want rings and bar as one assembly rather than sourcing and drilling them separately.

Key Features & Design

• 90mm ring inside diameter: takes tubes up to 80mm outside diameter and smaller, with the adjustment screws centring them.
• 3-point adjustment: each ring carries three screws, so the tube is held at three contact points and can be centred and rotated.
• 8″ Vixen bar included: the rings arrive mounted on the bar, so there is no separate bar purchase and no drilling.
• Supplied as a pair: two rings, for front and rear support along the tube.
• Published weight: 1.563 lb for the assembly, made in the USA.

Mechanical Design

Three-point adjustment is what lets one ring size serve a range of tubes. Instead of a ring bore that matches a tube's diameter exactly, three screws meet the tube at three separate points around its circumference, and a circle resting on three points is located in both axes — so a smaller tube sits centred rather than dropping to the bottom of the ring. Backing off one screw and taking up another rotates the tube in place, which is how a focuser or finder is brought round to a working angle without unclamping the whole assembly. Where the two rings sit along the 8″ bar sets how far apart the support points are.

Recommended Uses

• Mounting a small refractor or guide scope up to 80mm O.D. on a Vixen saddle.
• Rotating a tube in the rings to bring the focuser or finder to a working angle.
• Building a guide scope assembly that lifts off the main rig as one piece.
• Replacing a fixed-bore ring set with one that adjusts to the tube.

Compatibility and Accessory Notes

The bar is the V-size (Vixen-style) standard and fits any Vixen saddle, which covers most small and mid-size equatorial and alt-az mounts; D-size (Losmandy-style) saddles take a D-size bar instead. The ring inside diameter is 90mm and suits tubes up to 80mm outside diameter — Farpoint's guide is a ring I.D. at least 10mm larger than the tube. Larger tubes are covered by the 108mm set (up to 98mm O.D.) and the 125mm set (up to 115mm O.D.). If you are unsure of your tube's outside diameter, we can look the figure up for your scope model.

Good to Know Before You Order

• Sized by tube O.D., not aperture. The 90mm rings are matched to a tube outside diameter of up to 80mm, which is larger than the optic's aperture.
• Bar length is fixed. The rings come on an 8″ bar, which sets the available range for ring spacing and for balance in the saddle.
• V-size standard. The bar seats in Vixen saddles; a Losmandy-only saddle takes an adapter or a D-size bar.
• Three-point contact. The tube is held at three points per ring rather than around the full circumference.

Frequently Asked Questions

What's included?

Two 90mm I.D. rings with 3-point adjustment, already mounted on an 8″ Vixen-style dovetail bar — a complete assembly with no separate bar purchase and no drilling.

What ring size does my scope need?

Farpoint's guide is a ring I.D. at least 10mm larger than the tube's outside diameter. The 90mm set covers tubes up to 80mm O.D., the 108mm set reaches 98mm, and the 125mm set reaches 115mm.

What mounts will this work with?

Any mount with a Vixen-style (V-size) saddle — the narrower of the two common dovetail standards, found on most small and mid-size equatorial and alt-az mounts.

Is it difficult to set up?

The rings arrive on the bar, so setup is opening the rings, laying the tube in, taking up the three adjustment screws on each ring, and dropping the bar into the saddle.

Bottom Line

In short: two 90mm 3-point rings on an 8″ Vixen bar, 1.563 lb complete, for tubes up to 80mm outside diameter.