The Astro-Tech #ATF multiple reticle finder is a single-power illuminated multiple reticle red-dot finder for astronomy and daylight terrestrial use. The lightweight and compact Astro-Tech finder features a precision ground reflex lens viewing window with minimal parallax; four different reticle patterns; seven brightness levels; and a two-part mounting base for installing the finder on a variety of telescopes.
Any of four different reticle patterns can be selected by a lever at the rear of the finder. They include a single dot, such as that found in most traditional red dot finders; a plain crosshair; a circle with four short bars that extend out from the edges of the circle; and a dot within a circle.. The reticle patterns are projected on a multicoated optical glass viewing window that's roughly the proportions and shape (but not the actual size!) of a 16 x 9 HDTV screen. When the sky is viewed through the window, the red reticle appears to be superimposed on the sky or daytime landscape. You can choose the reticle pattern that best suits your viewing style and personal preferences. The actual projected reticles can be seen in the feature image below. A rubber cover is supplied to slip over the glass screen to protect its premium coatings when the scope is not in use.
The Astro-Tech finder is CNC-machined from solid aluminum for strength and durability, rather than being molded of fragile plastic, as are most red-dot finders. The finder is anodized a non-reflective matte black. The finder's matte black dovetail base is also CNC-machined from aluminum stock.
The supplied two-piece finder base can be used in either of two ways. The mounting stalk by itself is 13.5mm wide and will fit into the finder mounting bracket provided with most larger Astro-Tech and TMB refractors and into the Antares quick release finderscope bracket, as well as into most other brands of quick release bracket shoes.
If both pieces of the two-piece base are used, the curved base will mount on small Astro-Tech refractors, the TMB-80 refractor, and most William Optics and Stellarvue refractors (all using the 5mm mounting hardware supplied with the base). The underside of the mounting shoe is felt-lined to keep from scratching your telescope's finish.
The two-piece base can also be used on most catadioptric telescope rear cells (using the existing telescope trim hardware that seals the accessory mounting holes located at the 1 o'clock position on the telescope's rear cell). The sharper curvature of the base needed to fit smaller refractor bodies may leave a small cosmetic gap between the underside of the base and a larger catadioptric telescope body, but this will not affect the performance of the finder.
The two-piece finder base is also available separately (our part #ATFB), allowing you to install the Astro-Tech finder on two scopes without having to change the base between scopes. An optional finder base is also available (our part #ATFBV), that will let you install the Astro-Tech finder in a Vixen/Celestron/Orion-style finderscope mounting shoe.
Click-stop azimuth and altitude hex head adjustment bolts allow you to line up the finder with your main scope optics. The adjustments are very accurate, with each click stop equal to 1 arc minute of position change. The appropriate hex head wrenches are supplied for both clamping the finder to its base and making the altitude and azimuth adjustments.
There is a combined on-off switch and rotary brightness level control on top of the finder. The control provides seven click-stop brightness levels, allowing you to match the finder brightness to all lighting conditions and targets, from lining up on the Moon to the locating faint naked eye stars without having the finder brightness overpower the faintest stars.
The finder uses one user-replaceable 3 volt CR2032 lithium camera battery (supplied). Battery charge and battery life are not covered by the finder warranty. Replacement batteries are readily available at Wal-Mart, Radio Shack, camera stores, etc.
