Questar 3.5 ″ telescope
The Questar 3.5 ″ telescope is a Maksutov-Cassegrain telescope manufactured from 1954 to 2000 by Questar Corporation , based in New Hope , Pennsylvania .
Questar 3.5 ″ (specification from 1961)
The Questar 3.5 ″ standard telescope manufactured for amateur astronomers has a free aperture of 88.9 mm, which results in an aperture ratio of at a focal length of 1280 mm . The rear end of the tube is closed by a housing, which contains the focus adjustment screw, the diagonal prism , the eyepiece carrier , the Barlow lens , the viewfinder and the associated controls. A camera adapter for focal photography can be attached to the rear of the housing . Accessories include an on the lens screw- sun filter , in addition, the QMax , a product manufactured by Questar sun spectrometer , available for connection to the Questar telescopes.
The diagonal prism can be moved sideways to reveal the beam path for the vertically built-in viewfinder and focal photography. The viewfinder has a focal length of 100 mm, with the inserted 24 mm eyepiece this results in a 4x magnification. The object to be observed is captured by a 45 ° mirror attached under the housing, which can be dimmed with a switchable solar filter. The Barlow lens, which can be switched on above the star diagonal, increases the focal length and magnification by 1.7 times. The lens hood , which also serves as a protection sleeve, is attached to the tube so that it can be moved.
The Questar-Brandon eyepieces (modified Plössl type, focal length 6/8/12/16/24/32 mm), diameter 1¼ inches, are provided with a thread. 1¼-inch (31.75-mm) eyepieces from other manufacturers and 2-inch eyepieces cannot be used.
The tube is mounted on an aluminum fork mount . This can be used azimuthally . With the plug-in supports included in the accessories, it can also be operated equatorially , directed towards the earth's axis. An electric motor of either 12, 110 or 220 volts is used for tracking . For higher demands, especially for photography, Questar also offers a polar cradle including a tripod.
variants
In the civil market, the Questar 3.5 ″ was offered in the following variants:
- 3.5 ″ Questar Standard , as described above. In 2000, 250 commemorative models of this type were offered.
- 3.5 ″ Field Model Questar , tube only
- 3.5 ″ Questar Duplex , tube can be removed from the fork mount without tools for placing on German mounts
- 3.5 ″ Questar Birder , modified field model, without engraved maps on the tube, fixed 10x viewfinder, for observing birds and other wild animals.
commitment
Although the production of Questar 3.5 ″ telescopes was intended for the private market, they were also used by the US aerospace authority NASA in both the Gemini program for earth photos and the Apollo program for exploring the moon . One customer was Wernher von Braun , he bought one of these telescopes in 1959.