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

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  1. J

    Star Testing

    Hi Randy, Roland Christen is the head of Astro Physics, a legendary manufacturer of astro telescopes and mounts with a very long waiting list due to the hand aspherizing done by Roland to make his scopes perform best. I am quite sure that he will not work on a spotting scope from another...
  2. J

    Star Testing

    Hi, regarding the star test, Henry has said what can be said without having a look ourselves. The digiscoped images look good enough for sth shot at 70x and straight out of the camera/smartphone. Please keep in mind that any digiscoped stunners you see in the gallery here or elsewhere are...
  3. J

    Star Testing

    Hi, yes, spotting scopes can have pinched optics, sometimes even only in cold conditions due to lenses sitting nice and snug at room temperature... a slight rattle is not sth to complain about with good optics... As for the amount of SA - it's minuscule in the image you showed and you can...
  4. J

    Star Testing

    Hi, that is called overcorrection... but not a lot... this is not due to being a fast apo though... If you can see only a bit of stig too if the seeing evens out, that is a better than average sample (with the average being fairly low in spotters, unfortuately). Can you compare to the Kowa...
  5. J

    Star Testing

    Hi, from what you described about what you saw (concentric circles on both sides), I would guess that your Kowa is quite good... and whatever spikes you see are either a little rough roof edge (Kowa has been known for those lately - are the spikes always at top and bottom?) or just bad seeing...
  6. J

    Star Testing

    Hi, it should be noted, that even for fast apochromatic ED triplets (and only those are affected by the effect Roland points out in the article quoted above), the star test is a useful tool to determine the optical quality. The only thing one needs to keep in mind that some mild undercorrection...
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