My shorter focal length instrument is Astro-Tech AT65EDQ quadruplet apochromatic refractor. Diameter of the objective lens is 65mm with focal length of 420mm giving an F6.5 system. The telescope is an astrograph, meaning that it is well suited for astroimaging because of its 44mm large corrected flat field.

At 2.8kg the telescope is quite heavy for its small size. That is due to very sturdy construction and quadruplet optical system (lots of glass). The telescope is delivered with tube rings and Vixen style dovetail, which I promptly replaced for a Losmandy dovetail.

The same telescope is sold in Europe under Teleskop Service brand as TS APO65Q.


This is the "business end" of AT65EDQ. This telescope is an apochromatic refractor, meaning that the chromatic aberration (CA) of its objective is well corrected. Optical system of this telescope consists of four elements in two groups. First group is objective consisting of three separate lenses. One of them is made of exotic FPL-53 glass with special dispersion properties, which is a key factor for eliminating CA. Fourth lens is a dedicated field flattener made of ED glass. Purpose of that lens is to give a flat focal plane which is important for imaging. Objective is fully multicoated for better light transmission.

Objective is protected with retractable dew and glare shield. The dew shield is rather short, and sometimes not enough to prevent dew forming on the objective. That is why I have to use dew heater as well. OTA is well baffled with knife-edge baffles.



AT65EDQ is equipped with a serviceable 2" rack-and-pinion focuser. The focuser is dual-speed with focus lock knob. The focuser tube is engraved with millimeter scale. At the end of the focuser tube there is a rotatable collar.

The focuser handles CCD camera like QSI503WSG quite well. It is rated for loads up to 3kg, but that seems to me a bit too optimistic.

Here you can see my typical imaging setup with AT65EDQ telescope and QSI583WSG camera on Losmandy GM-8 mount. Autoguiding is done via Orion SSAG. The telescope is equipped with a dew heater. After putting some effort into arranging all the cables, I found out that I get the best results if they just hang freely...