On clear nights, I mount my Samsung Galaxy S10 to my 130mm aperture telescope and take pictures of certain deep-sky objects. Recently, I took pictures of the Orion Nebula. In order to get the optimal single-exposure pictures, I set the ISO to 320 and the shutter speed to 4 seconds. The shape of the nebula's cloud and the colors were relatively apparent, but unfortunately, I noticed streaks just beginning to appear in my pictures. The 500 rule says that the exposure time is not enough to create streaks, but I'm looking through a telescope instead of just a DSLR with a lens attached to it.

Does the 500 rule apply to photography through a telescope?

  • $\begingroup$ It's much more of a guideline than a rule, it's also been called, the 200, 400, 500, and 600 "rule". It depends a lot on the resolution of your camera, so you have to experiment with your equipment. But it does apply as much to telescopes as any other lens. $\endgroup$ Jan 11, 2023 at 21:32
  • $\begingroup$ scantips.com/lights/stars.html $\endgroup$
    – Aaron F
    Jan 11, 2023 at 23:41
  • $\begingroup$ 500 Rule also is known as 200, 400, 500, 600,etc as given by @GregMiller. So a better term would be the NFX rule $\endgroup$
    – user47732
    Jan 17, 2023 at 7:20


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