This Sky & Telescope Hot Product for 2016 Astro-Tech 12" Truss-Tube Imaging Newtonian has:
- very fast f/4 focal ratio 12” Newtonian reflector optics
- carbon fiber truss tube design
- 2” dual-speed linear bearing Crayford focuser with 2” and 1.25” compression ring accessory adapters
- three built-in cooling fans for faster primary mirror cooldown
- 8 x 50mm finderscope in a quick-release bracket
- two Losmandy-style D-plate dovetails
This Sky & Telescope 2016 Hot Product 12” Astro-Tech AT12INT carbon fiber truss tube optical tube is a very fast focal ratio f/4 reflector that has been optimized for wide field imaging of faint deep space objects. It can be used with DSLRs and large format CCD cameras.
In addition to deep space imaging, the Astro-Tech AT12INT is also usable for solar system imaging as well as deep space and solar system visual observing. As the AT12INT’s large secondary mirror has been optimized for full-field photographic illumination, solar system visual contrast will be somewhat reduced compared to a longer f/ratio reflector with a smaller secondary.
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 AT12INT 12" Imaging Newtonian has . . .
Newtonian reflector optics: 12” aperture, 1220mm focal length, f/4 focal ratio. Parabolic primary mirror, with press-fit dust cover. Both primary and diagonal mirrors are ground and polished under computer control for guaranteed diffraction limited performance. They are coated with 96% reflectivity enhanced aluminum, and overcoated with a protective layer of silicon dioxide (quartz) for long life.
No-tool push-pull mirror cell: The die-cast aluminum primary mirror cell has six recessed push-pull collimation screws. The recessed screw design holds the mirror collimation more securely than exposed knobs that can be moved inadvertently.
Three built-in cooling fans: Three small low-vibration fans are mounted on the primary mirror cell. The fans are 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.
Carbon fiber truss-tube body: The 39.5” long Astro-Tech AT12INT optical tube uses carbon fiber truss tubes and CNC-machined stainless steel and aluminum hardware. Both the primary and diagonal mirrors have built-in light shields on the inside of the truss tube assembly to block ambient light.
The two front truss-tube mounting rings that form the diagonal mirror cage have a maximum diameter of 15.75". The two rings holding the carbon fiber tubes that form the primary mirror housing have a maximum diameter of 19.25". The carbon fiber truss tubes that form the primary mirror housing and connect the front and rear sections of the optical tube have a very low thermal coefficient of expansion. This keeps focus changes (due to tube contraction when the temperature drops during an exposure) to an absolute minimum.
2” dual-speed linear bearing Crayford focuser: The heavy duty linear bearing Crayford focuser has a 2” accessory holder, with a 1.25” accessory adapter. Both have non-marring compression rings.
The focuser has dual-speed focusing. There are two coarse focusing knobs. One knob 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 linear bearing Crayford 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. Focusing scales on top of the focuser drawtube are 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.
For essentially coma-free imaging with the AT12INT, 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.
Two Losmandy-style dovetails: Two 17-5/16" long Losmandy-style D-plate dovetails are installed on the AT12INT. One is used to mount the AT12INT on any equatorial mount of your choice that has a sufficient payload capacity to carry the 34 lb scope and any imaging accessories you might add. The second is available to mount a photoguide scope or other accessories.
Because of the 51 pound weight of the AT12INT, plus the weight of your ancillary camera equipment and any photoguide scope, installing the AT12INT on a German equatorial mount with a 90 pound or greater payload capacity is recommended. Such mounts include the 90 pound capacity Celestron CGE Pro and the 100 pound capacity Losmandy HGM Titan. Other suitable mounts are also available.
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.