Hello,
M36 and M38 open clusters, ASI071MC + 300-mm f/4.5 telelens.
First night with the ASI071. I screwed the camera into a Tair-3s, a 300-mm f/4.5 soviet telelens manufactured in 1985. No filter. The clusters were as usual more or less drowned in light pollution. The adaptation to the lens was directly made with one of the enclosed spacers.
105 x 15s, RAW16, bin1x, gain 300, cooler was off (sensor was at 8°C).
Image is sized down but, given the (surprisingly limited) chromatic aberration of the lens, raw frames showed numerous, punctual stars. No more than 4-6 pixles per star with voluntarily strong undersampling to diminish the effect of expected chromatism from the lens. The halos around brightest stars come from spherochromatism and levels adjustment. Red, faint stars also were altered by halos, while blue was not so spread. Anyway I had to lower color saturation because of the lens.
Tests performed with a Celestron 5 at F/6.3 (Celestron reducer corrector) showed very natural colors, manageable vignetting and important aberration at the edges because the F/6.3 reducer was designed for a field of 24mm in diameter: this is too narrow for the ASi071. Perhaps it works fine at F/10.
Future tests to come with a more traditional Newton.
My previous image was made with a monochrome camera and 5 different filters. Imaging is color with the 071 is incredibly much more comfortable of course.
Many tests to perform as soon as clouds vanish, possibly with some filter. And darks. And cooling.
Clear sky,
Nicolas
