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

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  1. B

    Eye test

    The glasses with one new lens arrived today and is a great improvement. It took three weeks, but the lab did a good job, and the lens seems to have been made accurately. Now that I know the prescription works well I will probably have the spare glasses lenses made to the same prescription as a...
  2. B

    Eye test

    The Crab Pulsar is the central star of maybe visual magnitude 16.5, which is very faint. The public observatory seems to be the University of Chicago telescope, possibly the Yerkes 40 inch refractor. It may be possible to see down to magnitude 20 with this. So the reference above may not really...
  3. B

    Eye test

    Thanks Ed. The pilot part is that she knew and understood scintillation and was able to state that the star was flashing. She was a good observer, and probably had good sight also. I suppose the professional astronomer regretted not believing her and pursuing this further, as he may have got a...
  4. B

    Eye test

    That is the difference between observational skills and acuity of vision. When a person has both of these to a high order then unusual observations can be made. I wouldn't have a clue with regards to birdwatching, as it is not a specialist subject for me. There was an interesting interview...
  5. B

    Eye test

    The four navy divers, including a doctor, who spent about a week in darkness, with occasional torch light, had to protect their eyes when they emerged from the Thai cave. The children who spent more than a fortnight in almost complete darkness would need to take extra care. Hopefully they were...
  6. B

    Eye test

    Doctors have 10 minutes to see patients, opticians 20 or maybe 30 minutes. This is not enough time for a comprehensive eye test. So they do what they are taught and use 6 metres or 20 ft and say it is infinity. My eye tests usually take 90 minutes, but the recent one 75 minutes as my eyes were...
  7. B

    Eye test

    Yesterday's eye test went well as my eyes were rested. One eye remains the same as a year ago. The other needs a change of 2.5 degrees in the axis for astigmatism. An extra 0.25 dioptre of power. 0.75 dipotre of prism correction, whereas last year there was no prism correction. I asked if the...
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