Astro-Tech Tube Rings

90mm Tube Rings
These 90mm i.d. Astro-Tech split and hinged optical tube mounting rings are made of solid
aluminum, anodized black for long life. They are felt-lined and have a large hand-tighten knob
to lock them on your optical tube. A heavy nylon washer prevents the knob from marring the
anodized finish. The rings have a 90mm internal diameter to fit refractors with a 90mm OD
tube, such as the Astro-Tech AT80 and all William Optics 80mm telescopes (all versions of
the Megrez 80 and ZenithStar 80, for example), plus any other scope with a 90mm OD tube.

There are five mounting holes on bottom of the rings for mounting on most equatorial mount
dovetail plates. The center three holes are 6mm metric threaded, while the outer two are 1/4”
-20 thread. One 6mm hole is centered in the flat mounting boss in the bottom of each ring. It
is flanked by a pair of 6mm holes on 60mm centers, and a second wider pair of 1/4”-20 holes
on 80mm centers. An identical set of five holes on the top of each ring allow installing a
second dovetail plate to carry accessories. Two 16mm long x 6mm hex head metric bolts are
supplied with each ring for mounting the ring on a dovetail plate or equatorial mount using the
center hole or two flanking holes.


114mm Tube Rings
These 114mm i.d. Astro-Tech split and hinged optical tube mounting rings are made of solid
aluminum, anodized black for long life. They are felt-lined and have a large hand-tighten knob
to lock them on your optical tube. A heavy nylon washer prevents the knob from marring the
anodized finish. The rings have a 114mm internal diameter to fit refractors with a 114mm OD
tube, such as the Takahashi FS-102 and FSQ-106, William Optics FL-105, plus any other
scope with a 114mm OD tube.

There are five mounting holes on bottom of the rings for mounting on most equatorial mount
dovetail plates. The center three holes are 6mm metric threaded, while the outer two are 1/4”
-20 thread. One 6mm hole is centered in the flat mounting boss in the bottom of each ring. It
is flanked by a pair of 6mm holes on 60mm centers, and a second wider pair of 1/4”-20 holes
on 80mm centers. An identical set of five holes on the top of each ring allow installing a
second dovetail plate to carry accessories. Two 16mm long x 6mm hex head metric bolts are
supplied with each ring for mounting the ring on a dovetail plate or equatorial mount using the
center hole or two flanking holes.

90mm Finder/Photoguide Ring System
The photoguide system has two parts. Part one is a pair of guidescope mounting rings bolted
to a dovetail rail. Part two is a dovetail shoe that holds the ring system to your scope. This
shoe bolts onto a catadioptric scope’s rear cell, using the finderscope/accessory holes
generally located at the 10 o’clock and 2 o’clock positions on the rear cell. The 10 o’clock
holes normally hold the telescope’s factory-equipped finder, while the 2 o’clock holes are for
mounting accessories, such as this photoguide ring set. The dovetail shoe will work on the
rear cells of catadioptric scopes up to 20” in aperture.

The ring system can also be used on other scope types, providing the scope has a pair of
accessory mounting holes on the industry standard 1.25” centers (or can be drilled with such
holes, as in the case of a Sonotube or aluminum optical tube reflector.) Proper installation of
the mounting ring system on scopes other than Celestron or Meade 7” and larger
catadioptrics is the responsibility of the buyer.

The mounting rings have a 95mm (3.75”) internal diameter and will hold optical tubes with an
o. d. of 60mm to 90mm. Three large chrome finish hand-tighten collimating bolts with non-
marring Delrin tips in each ring allow you to collimate the refractor with the main telescope
optics when it is used as a finderscope, or to aim the refractor off-axis to locate an
appropriate guide star or photographic target when it is used as a photoguide or astrograph.
The knurled heads of the collimating bolts are nearly 3/4” in diameter, providing a sure and
easy grip, even while wearing gloves in cold weather.

The complete ring system and mounting shoe weighs only 17 ounces. All parts are machined
aluminum, anodized flat black to match the finish of most catadioptric scope rear cells. The
machined mounting hardware is finished in non-rusting chrome for long life. Mounting
hardware is provided to install the system on a Celestron or Meade catadioptric scope, as is
the appropriate size installation wrench.

Prices:
90mm Rings - £61.00
114mm Rings - £69.00
90mm Finder - £51.00

The Astronomy Shop

1 Tone Hill. Wellington

Somerset TA21 0AU

United Kingdom

Telephone: +44 (0)1823 665510