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

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  1. H

    Impact of TSN-EX16 on FOV?

    Looks like my explanation didn't quite succeed. Real FOV does not get wider as magnification increases. In the Kowa zoom and in most other zoom eyepieces it's the apparent FOV that increases as magnification increases, but that increase is much too small to make up for the loss of real FOV as...
  2. H

    Impact of TSN-EX16 on FOV?

    The extender is basically a Barlow lens placed in front of the eyepiece field stop, so it has no effect on the apparent size of the field stop as viewed from the eye behind the field stop. The apparent FOV follows the same curve from about 60º at the lowest magnification to about 80º at the...
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