the amazing STELLARVUE 180MM REFRACTOR
This hand-crafted apochromat raises the bar for refinement in build and image quality.
THE CAMBRIDGE DICTIONARY defines magnificent as “deserving to be admired.” I had no trouble doing that when I walked into the offices of Stellarvue to get an extension ring for my SVX140T and to visit my friend and Stellarvue owner Vic Maris: While there, I witnessed an SVX180T 180mm f/7 refractor being prepared for shipment to some lucky customer.
Until that moment, I had been happy with my Stellarvue 140mm f/6.7, but the power of 180mm dwarfed it by comparison. Completely captivated, I put a deposit down on a 180mm and waited — these hand-crafted instruments can take months to assemble. Fortunately, Stellarvue was in full production and just four months later I got the longawaited call saying “Your scope is ready, come pick it up!” The time has finally arrived
The first thing you notice when you see this telescope is that it is massive. No effort was spared to make this the ultimate refracting telescope. For example, although the objective is 180mm, its fully baffled tube is 8 inches (203 millimeters) across. This aids in thermal stability as heat currents are more likely to stay out of the optical path. The dew shield is also large enough to give the front of the objective room to breathe and ample space for dew control. The 180mm scope has three options for the focuser; I chose the Starlight Instruments 3.5" focuser, which is extremely rugged and well made. Stellarvue built a huge field flattener for imaging — as an optional addon — that fastens directly to the focuser and covers any size camera with the right adapters.
To see how well a telescope baffles light, do this experiment: Place a white, well-lit board in front of the telescope, remove the eyepiece and diagonal, and look through the scope. What do you
see? A well-made refractor should show you nothing but the bright white circle of the lens surrounded by a black void, whereas a poorly made refractor will make a bright star look like a colorful blur. When you perform this test on the Stellarvue 180mm refractor, a clear, bright point is exactly what you’ll see. The scope is extremely well baffled, so any spurious light is blocked from reaching the eyepiece or camera.
My original intent for purchasing this telescope was for visual use, as I own a large corrected Dall-Kirkham reflector for astrophotography. And for several months, that is how I employed the 180mm. As expected, the contrast was superior, the illumination was beautifully even, and the smallest stars were mere pinpricks. The planets and the Moon appeared the best I have ever seen them during moments of good seeing.
One event really stands out: One night I was looking at the craterlets in the lunar crater Plato. As I looked at one of the craterlets, it seemed to split into two. Bad seeing? Thermal effects? But the more I looked, the more I was convinced I was seeing a real double craterlet. The next day I looked up a NASA picture of Plato and lo and behold, there is indeed a double craterlet there. It was the first time I saw this with any telescope. I was also surprised at how well the 180mm handled deep-sky objects. It was nice to see M81 and M82 in the same field of view with an added Pentax 40mm XW eyepiece. The views through this fine instrument are excellent.
But Vic was curious how the scope would perform photographically in my hands — and so was I. With the assistance of some friends, I pulled my reflector from its imaging mount and installed the 180mm in its place. For the next several nights, I ran the scope through several tests with my complementary metal-oxide semiconductor (CMOS) camera and noted how sensitive the scope was to temperature changes. I decided to also add the automated Starizona’s Microtouch focus motor, with built-in software for temperature compensation, to the rig.
The power of an APO Lens
One of the questions I hear about the 180mm is whether it is a true apochromatic (APO lens), where all the colors focus in the same spot. This question highlights a classic difference between a reflecting telescope and a refracting telescope. A reflector brings all the