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

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  1. B

    New but probably wrong insight about lowlight

    With a 50x50 the moon covers 25 degrees but has low surface brightness. With a 7x50 the moon covers 3.5 degrees with high surface brightness. But I suppose the total moon light is the same. Regards, B.
  2. B

    New but probably wrong insight about lowlight

    I think what is being discussed as brightness is in fact surface brightness. The pupil size does oscillate slightly and is not constant in size. The eye is a good photometer when it comes to comparing luminosity. Accurate to about 9% or 10% with an experienced viewer, but not everybody has...
  3. B

    New but probably wrong insight about lowlight

    Not really. Much fainter stars are visible in a 20x50 compared to a 10x50 because the sky background is darker. In fact, stars twice as faint are visible in the 20x50 or about 0.7 0r 0.8 magnitude fainter. In addition, many binoculars are vignetted, so 10x50s are typically 10x47. The Optolyth...
  4. B

    New but probably wrong insight about lowlight

    Actually it depends what you are looking at. If you want to see fainter stars then 10x42 is better than 8x42 by about 25%. If you want to see extended faint detail then 8x42 is better than 10x42. In addition, eyes vary a lot. At age 60 my pupils were 6mm and my friend's still 7mm at that...
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