Hello,
Just playing around with the Kowa 663M + 20-60 I received recently. This is my first time with star tests. I will soon post some pictures once I get those adapters. There were two really big skyline buildings behind our apartment a little more than a couple of miles away, on top of which there are a few bright red lamps. Some switch on and off. I thought I would use those as a point source.
My preliminary observations at 60X max magnification across the various light sources indicate: circular rings, and clean center both inside and outside of focus - indicating potentially low astigmatism & coma. The rings were sharper and brighter outside of focus; the rings were still distinguishable inside of focus, however they appeared less bright, and less sharp. Relating this observation back to the spherical aberration section in: https://starizona.com/tutorial/star-testing-telescope-optics/ , indicates that this could be a potential case of overcorrected spherical aberration?
Is this a bad thing? And under what conditions can I imagine this issue to influence wildlife & potentially some stargazing observations in a bad way?
Again, sorry for not attaching pictures. I will update the thread hopefully soon with those images, and a resolution test.
Cheers,
Kumar
Just playing around with the Kowa 663M + 20-60 I received recently. This is my first time with star tests. I will soon post some pictures once I get those adapters. There were two really big skyline buildings behind our apartment a little more than a couple of miles away, on top of which there are a few bright red lamps. Some switch on and off. I thought I would use those as a point source.
My preliminary observations at 60X max magnification across the various light sources indicate: circular rings, and clean center both inside and outside of focus - indicating potentially low astigmatism & coma. The rings were sharper and brighter outside of focus; the rings were still distinguishable inside of focus, however they appeared less bright, and less sharp. Relating this observation back to the spherical aberration section in: https://starizona.com/tutorial/star-testing-telescope-optics/ , indicates that this could be a potential case of overcorrected spherical aberration?
Is this a bad thing? And under what conditions can I imagine this issue to influence wildlife & potentially some stargazing observations in a bad way?
Again, sorry for not attaching pictures. I will update the thread hopefully soon with those images, and a resolution test.
Cheers,
Kumar
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