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

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  1. W

    HDF 40831 vs 40810 question (and other specs)

    I got the 23x fixed after the SDL3. I was always a bit irritated with the SDL3 at the low end (too narrow) and sometimes at the top end (seems to dim and drop in contrast suddenly), so I normally use it at an “optimum power” around 30x or so depending on the lighting. Being able to adjust as...
  2. W

    HDF 40831 vs 40810 question (and other specs)

    Something like this maybe… ? Could need updating and collating. https://www.opticron.eu/ukhtml/Pages/eyepieces_archive.htm https://www.birdforum.net/attachments/scope-and-eyepiece-focal-lengths-xlsx.589390/ Peter
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