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

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    New Sub Forum needed - Astro scopes for Visual

    I have an idea that seems to be missing here. The Digiscoping forum includes telescopes for photography but what about a sub forum here to use astronomy scopes as visual field work devices? I don't always want to use a camera for circumstance when out in the field. Sometimes, I just want to...
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    Backwards close-up filter???

    A dumb physics question from me. What happens if a close-up filter is installed backwards on the front of a telescope? Will it still have the rated +diopter effect? The better quality close-up filters are cemented doublets but I cannot find out info about whether direction of the light...
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    Can a barlow be used on a camera lens?

    This question of mine does not seem to fit anywhere else, so I will ask it here. If I have a 300mm Pentax m42 lens that has a focal plane of 45.5mm from the rear end of the lens to the "film" sensor on my APS-C DSLR camera, AND, I have a 2X barlow that has a -63mm focal length with T-threads on...
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