TS Optics AP 90/540 OTA

Description

Ohara FPL-53 Super ED glass paired with German Schott glass powers the TS Optics AP 90/540 OTA wide field deep sky refractor optical tube assembly. Operating at a fast f/6.0 focal ratio with a 540mm focal length, this 90mm (3.54 in) clear aperture instrument delivers a 1.29 arcseconds theoretical resolving power and reaches magnitude 12.5, gathering light for high-resolution deep-sky imaging and true color-free lunar and planetary visual observation.

The optical system features an air-spaced true APO triplet objective housed in a temperature-compensated lens cell, treated with broadband fully multi-coated (FMC) layers and an unobstructed 0% central profile. Built inside an aluminum chassis measuring 435mm retracted and 495mm extended with a 114mm outer dew shield diameter, the tube assembly supplies 150mm of back focus from the 2-inch visual back (55mm standard from dedicated M48 flattener threads). Equipped with a 2.5-inch dual-speed rack-and-pinion focuser, an M63x1 rear thread, and a 360-degree field rotator, this 3.80 kg (8.38 lbs) refractor illuminates a 44mm full-frame image circle when paired with dedicated correctors.

Key Features of TS Optics AP 90/540 OTA

Built for wide-field astro-imaging and high-contrast planetary viewing, this 90mm triplet pairs certified optical glass with a heavy-duty 2.5-inch rack-and-pinion focuser. CNC-machined split tube rings, a top utility carrying handle, and a padded aluminum transport case provide rigid support on medium-capacity tracking mounts.

• 90mm (3.54 in) clear aperture with 540mm focal length and fast f/6.0 optical speed
• Air-spaced true APO triplet objective featuring Ohara FPL-53 and German Schott glass
• Broadband fully multi-coated (FMC) anti-reflection layers with 0% central obstruction
• 2.5-inch dual-speed rack-and-pinion focuser 1:10 with M63x1 thread and 360-degree rotator
• Generous 150mm back focus distance measured from the 2-inch visual back
• Corrected 44mm full-frame image circle when paired with dedicated flattener or reducer
• CNC-machined tube rings with 44mm Vixen-style dovetail bar and top utility handle
• Step-down 2-inch to 1.25-inch adapter and custom padded aluminum case included

Temperature-Compensated FPL-53 & Schott Triplet Cell

An Ohara FPL-53 Super ED center lens mated with German Schott elements in a temperature-compensated cell controls secondary spectrum chromatic aberration across visible wavelengths. The unobstructed 90mm optical path preserves natural color contrast on planetary discs and lunar terminator details, supporting practical magnifications from 12.9x up to 180x.

Direct M63 Threaded Coupling & Rotational Mechanics

Holding cooled astronomy cameras and filter wheels requires drawtube rigidity without mechanical flexure under load. The 2.5-inch rack-and-pinion focuser features a 1:10 micro-reduction drive, an M63x1 threaded rear interface, and an integrated 360-degree field rotator for composition framing. Transported in a padded aluminum case, this 3.80 kg optical assembly remains protected in the field.

• 2.5-inch dual-speed rack-and-pinion focuser with 1:10 micro-reduction for precise focal adjustment
• Integrated 360-degree camera field rotator with direct M63x1 threaded mechanical coupling
• Custom padded aluminum transport case providing impact protection during field trips

TS Photoline Triplet APO Series Warranty

The TS Optics AP 90/540 OTA is backed by a 2-year limited warranty against material and manufacturing defects. The complete factory package contains the 90/540 Triplet OTA, retractable dew shield, CNC-machined tube rings, Vixen dovetail bar, carrying handle, 2-inch to 1.25-inch adapter, and a padded aluminum case.