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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Nikon ED50, ED82 star tests (1 Viewer)


Active member
Did some star testing on my ED82 and ED50 with a led light and foil with pin hole approx 25m away

ED50 tested better with easily visible perfectly round defocused rings inside and outside focus.
Pictures show them as oval rings for some reason.

ED82 had round defocused rings, inside focus had more easily distinguishable rings than outside.


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    ED82 inside focus.jpg
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  • ED82 outside focus.jpg
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  • ED50 inside focus p.jpg
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  • ED50 outside focus.jpg
    ED50 outside focus.jpg
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Thanks for the test images. Would've been interesting if you had star test images of the returned Monarch to compare with these.

My inexperienced impression is the brightened center in one side and darkened on the other side indicate there is spherical aberration on both scopes, though the smaller scope has less of it. Also a bit of coma on the larger and none on the smaller. Hope someone with better experience and knowledge will chime in and correct me.
Possibly spherochromatism, but nothing to worry about.

The more interesting feature is the departure of ED 82 from perfect circular symmetry. Has the scope acclimatised properly - how long has it been out before the test? Was the Sun shining at it?

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