Testing the TecnoSky AG70

On loan from a friend, I could spend some clear nights with this short-focus flat-field refractor. It has 70mm aperture and 350mm focal lenght, for an F/Ratio of F/4,9. It delivers a nice illuminated field and pinpoint stars almost to the corners of the frame. Some slight blue fringing is present near the corners. Focusing is very critical, and also very temperature-dependent. An autofocuser is almost indispensable to keep control over the focus.

Aldebaran non-cropped FF field without any filters (only stacked and stretched)
Aldebaran in B/W non-cropped fullframe with the Oprolong L-Pro (some fog or high clouds) only stacked and stretched
Cone & Christmas Tree nebulae, in B/W with the Nikon D750 (stitch line visible )
NGC2244 or Rosette Nebula mosaic 3+3 hrs Nikon D750 & TecnoSky 70AG

Heart in the Sky

The Heart Nebula in Perseus is an interesting region of red hydrogen clouds mixed with dark nebulosity and bright star clusters. This was a test-run: first light with the Sequence generator Pro combined with the Nikon D750 (with autofocus by PegasusAstro, worked wonderfull). Second test (living dangerously!): first attempt to mosaic automatically with SGP.

The D750 would crash SGP when hitting the “link” button: as soon as I touched that button, SGP would collapse and simply vanish in thin air. Solution: install the 2013 C++ redistributables.

The Optolong Pro filter OR the reducer/flattener (or the combination) imho added a lot of vignetting and uneven illumination to the image, which I had a hard time eliminating. So next test would be with a regular Nikon T-ring. If that does not solve the issue then it must be the F5 reducer. I noticed earlier already that images at F7 with the Nikon were a lot cleaner.


IC1805 or the Heart Nebula in Perseus. Image dedicated to my mom who passed way in September age 79. 

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