Farpoint 160mm D Style Dovetail Rings

Product Overview

The Farpoint FDR160 is a pair of rings with a 160mm inner diameter that bolt to a D-size (Losmandy-style) dovetail plate and carry a guide scope, finder, or other optical accessory above the main telescope. It is the largest ring in the Farpoint D-style line, sized for tubes with an outer diameter below 150mm. Three adjustment screws per ring centre the tube, hold it, and set where it points. The pair ships with standard 1″ screws, CNC-machined in the USA, at a published weight of 2.313 lb.

Who It's For

This is a good match if you…

• are carrying a larger secondary tube — a short refractor rather than a small guide scope.
• have a tube with an outer diameter in the 130–150mm range.
• already run a D-size dovetail plate and want to add a second optic above the main tube.
• want the secondary tube aimable so a guide star can be brought onto the sensor.

Key Features & Design

• 160mm inner diameter: the largest in the D-style ring line, holding tubes with an outer diameter below 150mm.
• Three-point adjustment per ring: six screws across the pair centre the tube and set its aim.
• Standard 1″ screws included: short .5″ and long 1.5″ sets are sold separately to match screw reach to tube diameter.
• D-size mounting: the rings bolt onto a Losmandy-style dovetail plate.
• Supplied as a pair: two rings, supporting the tube at two points along its length.
• CNC-machined in the USA: produced by Farpoint in the United States.

Mechanical Design

Each ring carries three screws spaced around its circumference rather than a single pinch bolt. Three points of contact define the position of a cylinder, so the tube is centred by geometry rather than squeezed against one side of the ring. Turning the screws differentially tilts the tube within the ring by small amounts, which is how a guide star is walked onto a sensor without moving the main telescope. Screw length is matched to tube diameter because the adjustment range depends on how far the screws reach inward: a tube close to the 150mm working limit sits near the ring wall and suits the short .5″ screws, while a much smaller tube needs the long 1.5″ screws to reach it. At 160mm this is the largest ring in the line, so it is carrying more mass at a greater radius than the smaller rings — the two-ring spacing along the tube is what holds that load rigid. The underside bolts to a D-size dovetail plate, so the assembly clamps into the mount as one unit.

Recommended Uses

• Carrying a short-tube refractor piggyback above a main imaging telescope.
• Running a larger guide scope where a small finder-style guider is not enough aperture.
• Dual-scope imaging where the secondary tube is a wide-field optic in its own right.
• Mounting a large spotting scope or rich-field tube on a D-size plate for visual work.
• Building a permanent imaging train where the secondary tube stays aligned between nights.

Compatibility and Accessory Notes

The rings mount to D-size (Losmandy-style) dovetail plates, which are sold separately — Farpoint's universal D-size dovetail bars are the usual pairing. On the tube side, the rings work with any tube whose outer diameter is below 150mm; Farpoint's guidance is to pick a ring at least 10mm larger than the tube O.D. so the adjustment screws have travel to centre it. The rest of the line covers smaller diameters: 90mm rings for tubes below 80mm, 108mm rings for tubes below 98mm, and 125mm rings for tubes below 115mm. Ring screws come in .5″, 1″, and 1.5″ lengths. A V-size (Vixen) rig takes Farpoint's Vixen scope rings instead. If you are unsure which ring size suits your tube, we are glad to work it out — the tube's outer diameter and your dovetail standard are all we need.

Good to Know Before You Order

• The dovetail plate is sold separately. The rings bolt to a D-size plate you supply; the plate is not part of this item.
• Tube outer diameter below 150mm. A 160mm ring leaves roughly 10mm of working clearance, which is the span the adjustment screws take up.
• A much smaller tube suits a smaller ring. Dropping a 90mm tube into a 160mm ring leaves 35mm per side for the screws to span, which is where the long 1.5″ screws come in — or a 108mm or 125mm ring instead.
• Standard 1″ screws ship with the rings. The .5″ and 1.5″ sets are separate purchases.
• Published weight is 2.313 lb for the pair. The tube it carries adds to that figure against the mount's rated capacity.

Frequently Asked Questions

Will these fit my guide scope?

They hold any tube with an outer diameter below 150mm. The ring works best with at least 10mm over the tube O.D. so the three screws per ring can centre and grip it. For a tube much smaller than the ring, the long 1.5″ screws add reach.

Is the dovetail bar included?

No — the rings bolt to a D-size (Losmandy-style) dovetail plate, which is a separate item.

What is the 3-point adjustment for?

Each ring has three screws spaced around the tube. They centre the tube, hold it, and let you fine-tune where it points, which is how a guide star is placed on the sensor.

Is it difficult to install?

The rings bolt to the dovetail plate with hex hardware, then the tube drops in and the three screws per ring are snugged evenly. It is a hand-tool job, and the rings can stay on the plate between sessions once set.

How does this compare with the 125mm rings?

Same design and the same three-point adjustment; the 160mm rings hold tubes below 150mm O.D. where the 125mm rings hold tubes below 115mm.

Bottom Line

In short: the largest rings in Farpoint's D-style line — a machined 160mm pair with three-point adjustment, carrying tubes below 150mm O.D. on a Losmandy-style dovetail, at a published 2.313 lb.