|Télescopes astronomiques / Telescopes for astronomy | Réflecteurs de Newton / Newtonians |
NEWTONIEN DE PHOTO 10" ASTRO-TECH / ASTRO-TECH 10" IMAGING NEWTONIAN
This Astro-Tech Imaging Newtonian optical tube has:
• very fast f/4 focal ratio 10" Newtonian reflector optics
• contrast-enhancing extended tube length
• 3.3" dual-speed linear bearing Crayford focuser with 2" and 1.25" compression ring accessory adapters
• built-in cooling fan for faster primary mirror cooldown
• 8 x 50mm finderscope in a quick-release bracket
• dual split hinged mounting rings
This 10" Astro-Tech AT10IN optical tube is a very fast focal ratio f/4 reflector that has been optimized for very wide field imaging of faint deep space objects. It can be used with 35mm cameras, DSLRs, DSI-type cameras, and large format CCD cameras alike.
The standard equipment mounting rings of the 10" Astro-Tech Imaging Newtonian allow you to use it on a wide variety of dovetail plates and German equatorial mounts. Careful note should be taken of the weight of the AT10IN, however, at 29.25 pounds without mounting rings or finderscope. This scope will require a substantial and well-built German equatorial mount under it to provide optimum performance.
In addition to deep space imaging, the Astro-Tech AT10IN is also usable for solar system imaging as well as deep space and solar system visual observing. Solar system visual contrast will be somewhat reduced compared to a longer focal ratio reflector because of the AT10IN’s larger secondary mirror that has been optimized for full-field photographic illumination. Visually, the scope should probably be considered more of a deep space “light bucket," rather than a solar system scope. However, the visual performance within the solar system will still be much more than acceptable, and the 1016mm focal length of this 10" Astro-Tech makes it quite possible to achieve the high powers needed for detailed lunar and planetary observing. Simply add optional 1.25" or 2" eyepieces, and perhaps an optional Barlow lens, and this Astro-Tech Imaging Newtonian will provide you with crisp and sharply detailed close-up views of the Moon and planets.
This Astro-Tech Telescope’s Optical System . . .
* Newtonian reflector optics: 10" aperture, 1016mm focal length, f/4 focal ratio. Parabolic primary mirror. Both primary and diagonal mirrors are ground and polished under computer control for guaranteed diffraction limited performance, coated with 91% reflectivity aluminum, and overcoated with a protective layer of silicon dioxide (quartz) for long life.
The mirrors are made of B270 “water white" optical crown glass that is free of internal stress and striae. B270 glass is equivalent to BK7 in performance and optical quality. The thermal stability of B270 glass is generally better than the soda lime float glass used for the mirrors of most reflectors in this reasonable price range. For maximum contrast, the four secondary mirror spider vanes have been optimized to be as thin as possible without losing stability.
* No-tool push-pull mirror cell: The die-cast aluminum primary mirror cell has six hand adjust push-pull collimation knobs. These make it easy to collimate the primary mirror without tools, even while wearing gloves or mittens in cold weather. To further ease collimation, the primary mirror is center-spotted.
* Built-in cooling fan: A low-vibration/high CFM fan is mounted on the primary mirror cell. The fan is powered by a supplied battery pack that uses eight user-supplied AA batteries. Alternatively, the fan can be powered by a 12 VDC rechargeable battery if one is being used to power your mount’s drive system.
* Extended optical tube: To increase the contrast, the optical tube of the Astro-Tech AT10IN is extended 9.5" forward of the focuser centerline to act as a lens shade to keep ambient light from hitting the diagonal mirror. This results in higher contrast than a conventional reflector for both imaging and visual observing.
The white-painted 38.5" long x 11-7/8" diameter Astro-Tech optical tube (with 12-1/8" diameter front and rear cells) is fabricated of rolled steel, to allow the mirrors to cool to ambient temperature more quickly, aided by the built-in cooling fan. While the rolled steel optical tube is a little heavier than a more-costly aluminum tube, a Sky & Telescope review of the AT10IN’s 8" smaller brother AT8IN pointed out that a steel tube “also helps make it a very rigid setup, which is a good thing for astrophotographers." The scope’s tube end rings are sturdy die-cast aluminum, to protect the tube during transport and provide exceptionally rigid support for the optics.
* 3.3" dual-speed linear bearing Crayford focuser: The newly-designed heavy duty linear bearing Crayford focuser’s 3.3" drawtube ends in a step-down adapter to a 2" accessory holder. A 1.25" accessory adapter is standard equipment. Both the drawtube’s 2" accessory holder and the 1.25" accessory adapter have non-marring compression ring accessory holders.
The focuser has dual-speed focusing. There are two coarse focusing knobs. The knob facing the rear of the scope also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. A lock knob underneath the focuser lets you adjust the tension on the drawtube to accommodate varying equipment loads. A large lock knob on top of the focuser lets you lock in your photographic focus.
The new linear bearing focuser has a polished stainless steel drive rail that runs the length of the underside of the drawtube. The focuser’s stainless steel drive shaft presses on this drive rail to move the focuser, rather than having the hard steel drive shaft press directly on (and wear out) the softer aluminum drawtube as with conventional Crayford focusers. The steel drive rail rides in a self-lubricating track that extends almost the entire length of the focuser body. The drive rail and its attached drawtube are thereby supported over most of their length at all times, rather than by a conventional Crayford focuser’s two sets of small contact area roller bearings. This system distributes the drive force evenly over the entire drawtube, without concentrating it on a few small contact points. The result is a very rigid drawtube with essentially zero flexure and no wear (much less flat spots or uneven wear) on the focuser drawtube.
The focuser drawtube has 51mm (2") of travel. A focusing scale on top of the focuser drawtube is marked in inches and millimeters to make it easy to return to the approximate correct focus when setting up to image or observe each night.
Because of the 29.25 pound weight of the AT10IN (without mounting rings or finderscope) , plus the weight of your ancillary camera equipment and any photoguide scope, installing the AT10IN on a German equatorial mount with a 60 pound or greater payload capacity is recommended. Such mounts include the 90 pound capacity Celestron CGE Pro and the Losmandy 60 pound capacity G11 or G11 go-to and 100 pound capacity Losmandy HGM Titan. Other suitable mounts are also available.
For essentially coma-free imaging with the AT10IN, consider adding the Astro-Tech ATCC coma corrector to the scope. This imaging accessory essentially eliminates the coma inherent in all fast focal ratio reflector telescope designs, so that the coma-free star images remain point-like all across the field.
* Split tube rings: A pair of die-cast aluminum hinged split tube mounting rings are provided. Each ring has a flat boss on its underside with a 1/4"-20 thread mounting hole for installing the ring on a Vixen-style or Losmandy-style “D-plate" dovetail mounting plate. This lets you mount the scope on virtually any equatorial mount. In addition, there is a flat boss with a 6mm metric hole on the top of each ring. This allows you to install a separate dovetail on top of the optical tube for mounting photoguide rings and a guidescope or similar accessories piggyback on top of the AT10IN. The optical tube rotates in its felt-lined die cast cradle rings to bring the focuser and finder to the most comfortable viewing position.
* Finderscope: 8 x 50mm straight-through dark crosshair achromatic design, in a spring-loaded quick-release mounting bracket. The finder has a long and comfortable 13mm eye relief. To focus the finder, loosen the trim ring behind the objective lens cell, screw the lens cell in or out to focus, and tighten the trim ring to lock in the correct focus.
* Two-year warranty: All Astro-Tech telescopes have a two-year warranty.