TS Optics AP 70/474 OTA

Description

Corrected internally to illuminate a flat 44mm sensor circle without external flatteners, the TS Optics AP 70/474 OTA is a plug-and-play flat field astrograph refractor optical tube assembly. Operating at an f/6.77 focal ratio with a 474mm focal length, this 70mm (2.76 in) aperture telescope yields a 1.66 arcseconds theoretical resolving power and reaches magnitude 11.9, collecting photons for medium-scale nebula imaging, precision astrometry, and full-frame deep-sky astrophotography.

The optical system utilizes a Petzval-style quadruplet configuration featuring a front doublet objective combined with an integrated rear two-element field flattener, treated with broadband fully multi-coated (FMC) layers and an unobstructed 0% central profile. Built inside an aluminum chassis measuring 410mm retracted and 460mm extended with a 90mm outer dew shield diameter, the system achieves focus directly via drawtube travel without fixed sensor spacing constraints. Supported by a 2-inch dual-speed rack-and-pinion focuser and an integrated 360-degree field rotator, this 2.50 kg (5.51 lbs) astrograph produces edge-to-edge optical flatness across full-frame sensors.

Key Features of TS Optics AP 70/474 OTA

Designed for streamlined full-frame deep-sky imaging, this 70mm Petzval quadruplet pairs an Ohara FPL-53 element with an internal two-element field corrector. Its 2-inch rotatable rack-and-pinion focuser, precision CNC tube rings, and rigid aluminum transport case ensure stable field performance on portable tracking mounts.

• 70mm (2.76 in) clear aperture with 474mm focal length and f/6.77 optical speed
• Petzval-style quadruplet design with doublet objective and integrated rear field flattener
• Ohara FPL-53 Super ED element paired with specialized optical correction glass
• Broadband fully multi-coated (FMC) optical layers with an unobstructed 0% central profile
• Self-correcting Petzval field achieving focus directly along drawtube travel without spacer rings
• Corrected 44mm full-frame flat field image circle across modern digital camera sensors
• 2-inch dual-speed rack-and-pinion focuser 1:10 with built-in 360-degree field rotator
• CNC-machined tube rings, 44mm Vixen-style dovetail plate, and aluminum hard case included

Ohara FPL-53 & Internal Corrector Quadruplet Optics

Integrating a two-element rear corrector directly into the optical tube cancels field curvature and off-axis astigmatism across large camera sensors. The Ohara FPL-53 objective suppresses chromatic aberration around bright stars, while an unobstructed light path supports practical visual magnifications from 10.0x up to 140x.

Drawtube Focus Architecture & 360-Degree Camera Rotation

Eliminating backfocus spacer calculations allows imaging accessories to achieve focus directly through the 2-inch dual-speed rack-and-pinion focuser. A 1:10 micro-reduction knob provides fine focal control, while the integrated 360-degree rotator facilitates framing. Housed inside an aluminum hard case, this 2.50 kg optical assembly is protected during transport.

• 2-inch dual-speed rack-and-pinion focuser with 1:10 micro-reduction for fine focal positioning
• Integrated 360-degree camera field rotator for rapid composition adjustment without losing focus
• Custom aluminum hard case providing structural protection for remote dark-sky expeditions

TS Photoline Quadruplet Series Warranty

The TS Optics AP 70/474 OTA is backed by a 2-year limited warranty against material and manufacturing defects. The complete factory package contains the 70/474 Quadruplet OTA, integrated field flattener, CNC tube rings, Vixen dovetail plate, 1.25-inch adapter, and an aluminum hard case.