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

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  1. B

    FOV specs - reliable? comparable? red-herring?

    If you know angular size and movement in degrees per second you have a good idea what it isn't. I worked out I was probably seeing very faint buzzards at night, not helicopters, or faintly lit aircraft cockpits. Magnitude 7 in 18x50 IS binocular. Nowadays with drones, this might be more...
  2. B

    FOV specs - reliable? comparable? red-herring?

    Aircraft have crashed because pounds and litres of fuel were mixed up. The Hubble telescope was an initial disaster as the mirror was accurate but with the wrong curve. This would immediately have been spotted by a talented amateur telescope maker. I think the makers hoped the launch would...
  3. B

    FOV specs - reliable? comparable? red-herring?

    135m at 1000m is about 7.7 degrees. 404ft at 3000ft is also about 7.7 degrees. 404ft at 1000yds is the same as 134.7ft at 1000ft. 1000yds is 3000ft. It is a question of ratios or fractions in simple terms. B.
  4. B

    FOV specs - reliable? comparable? red-herring?

    A metre is not a yard and a yard is not a foot. It is a problem of math and of the obscure notion of so many feet at 1000 yards. I use angular measure, i.e degrees and decimals of degrees. Most good binocular makes are fairly accurate, although some are either deliberately or mistakenly...
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