On January 6, 2017, I was invited to a demonstration of the 4 1/2 inch telescope under development by Unistellar. I was present from 1930 to 2030 (sunset was at 1641). The site of the demonstration was southwest of Las Vegas, Nevada, a considerable distance out of town; however, the lights of the city could still be seen. Las Vegas is known for a variety of things, and near the top of the list is light pollution.
The sky conditions were partly cloudy, with a considerable amount of moisture in the atmosphere. Temperatures were close to 0°C. The moon rose at 1210 and set at 0021 and was in the 9th day of the lunar cycle at about 61% illumination. Site of the demonstration was the foothills of the Spring Mountains at about 1200 m elevation and about 75 m North of Nevada Highway 160.
Two telescopes were at the location: the Unistellar Prototype and a 16 inch Dobsonian provided by Fred Rayworth, a member of the Las Vegas Astronomical Society.
Although several stellar objects were viewed, the one of greatest interest was Messier object 42 [Orion Nebula]. It was located in the south eastern sky, about 30° from the moon. A considerable amount of time was spent looking at M–42 through each of the telescopes. Various filters were used on the Dobsonian Telescope in order to enhance the view of the nebula. The surprising result was that the images in the Unistellar Optics 4 1/2 inch telescope were clearer than those in the 16 inch Dobsonian. With the right filters, the quality of the image in the Dobsonian approached that of the image and the Unistellar scope, but Unistellar images were still superior [see image below]. It was an impressive demonstration.
I look forward to the time when the eyepiece is commercially available.
Jerry Stein, email@example.com
See also Fred Rayworth’s witness on Cloudy Nights