The above photo shows the Explore Scientific ED air-spaced triplet apochromatic refractor. The scope uses an air-spaced triplet objective made using extra-low dispersion (ED) dense fluor crown glass. The carbon fiber optical tube assembly is strong and lightweight, and I do not have to frequently refocus during the night as the temperature drops, because the carbon fiber tube does not change dimension at different temperatiues the way that a metal tube assembly typically does. This is a significant advantage for CCD imaging. The optical elements have enhanced multi-layer coatings to enhance light transmission. The optical tube assembly has internal knife-edge baffles to reduce light scatter and enhance contrast. This scope includes a 3-inch rack and pinion focuser that is extraordinarily smooth, and includes a 10:1 dual speed Feathertouch focuser. The heavy-duty focuser is custom made for Explore Scientific by Starlight Instruments, and easily handles the weight of the heavy SBIG STL-11000M CCD and Fingerlakes PDF electric focuser shown in the above photo. The scope includes an 8x50 right-angle finderscope with a 6 degree field of view that is right-side up and left-to-right correct. The holder conveniently includes a handle, which makes it easy to carry the optical tube assembly, especially since the carbon fiber tube makes the scope relatively light weight and easy to handle. According to the manufacturer, the optical tube assembly weighs 20.4 pounds.
This refractor has a 152mm objective lens, and a focal length of 1216mm. This results in a focal ratio of f8. The scope is shown with the SBIG STL-11000M CCD mounted to the scope, using a Fingerlakes PDF electric focuser mounted between the CCD and the scope. In the above photo, the ED152CF optical tube assembly is being carried on a Takahashi NJP Temma mount. The tube holder has a Losmandy style dovetail, and my Takahashi mount has a custom made dovetail adabter. In the configuration shown in the above photo, the scope is mounted on a telescope pad in my backyard, and I operate it remotely from inside the house.
This 6-inch refractor is used for both visual observing and CCD imaging.
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