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> Aperture diameter matters -- that's the total amount of light available. I think the point is the implied 'at that instant' which can be appended to your sta

by Jedd 9y ago

> Aperture diameter matters -- that's the total amount of light available. I think the point is the implied 'at that instant' which can be appended to your statement. Aperture matters in the context of a specific shutter speed. You allude to that 'aperture is everything' loophole in your comment on bullet point #3, about image stacking.

CydeWeys 9y ago
It also matters for resolving power though. You can take photos using a 1 m telescope with a one second exposure that you could never take using a 10 cm telescope at any exposure length. Keep stacking the photos for years, you're still not going to get the same detail. This is why the latest generation of land-based optical telescopes have truly mind-boggling apertures. Bigger is better in astrophotography, full stop. https://en.wikipedia.org/wiki/Extremely_Large_Telescope https://en.wikipedia.org/wiki/Extremely_Large_Telescope
- Jedd 9y ago
  Are you suggesting astrophotography has physical constraints that non-astro photography does not? More specifically, to your example, if a 1m (diameter?) telescope takes a photo with a 1s exposure -- you're suggesting that it will resolve more detail than one taken on a 10cm lens for 100 seconds?
  - CydeWeys 9y ago
    It's the same across all astronomical telescopes. And yes, resolving power is dependent on the size of the aperture. You can't make it up for it by combining many photographs taken with a smaller telescope. More information here: https://web.njit.edu/~gary/202/Lecture6.html https://web.njit.edu/~gary/202/Lecture6.html
  - simonh 9y ago
    The resolving power of a 1m scope isn't 100 times that of a 10cm scope. It's 10,000 times as much. Pi d squared. But I think the issue is that with super long time exposures things like lens and mirror aberrations, cumulative drift and rotation over time get magnified as well. As the exposure gets longer, the incremental benefit you get from each unit extension of the exposure decreases. Also, if you take 100x as long to do an observation, that's a hundredth as many observations you can do in any given amount of time.
  - gmiller123456 9y ago
    >Are you suggesting astrophotography has physical constraints that non-astro photography does not? No, he's saying the diameter of a lens affects its resolving power. This is due to the diffraction of light bouncing off the lens. Larger scopes have less diffraction due to the laws of physics.
    - CydeWeys 9y ago
      Lenses aren't used in "real" telescopes -- they're made out of mirrors only. Does your explanation still work?
      - gmiller123456 9y ago
        The mirrors in telescopes are still lenses. You're probably thinking of refracting lenses as being "real" lenses. But the parabolic mirrors used in telescopes accomplish the same task. And, yes, diffraction is still just as much of an issue.

by Jedd 9y ago

CydeWeys 9y ago

It also matters for resolving power though. You can take photos using a 1 m telescope with a one second exposure that you could never take using a 10 cm telescope at any exposure length. Keep stacking the photos for years, you're still not going to get the same detail. This is why the latest generation of land-based optical telescopes have truly mind-boggling apertures. Bigger is better in astrophotography, full stop. https://en.wikipedia.org/wiki/Extremely_Large_Telescope https://en.wikipedia.org/wiki/Extremely_Large_Telescope

Jedd 9y ago
Are you suggesting astrophotography has physical constraints that non-astro photography does not? More specifically, to your example, if a 1m (diameter?) telescope takes a photo with a 1s exposure -- you're suggesting that it will resolve more detail than one taken on a 10cm lens for 100 seconds?
- CydeWeys 9y ago
  It's the same across all astronomical telescopes. And yes, resolving power is dependent on the size of the aperture. You can't make it up for it by combining many photographs taken with a smaller telescope. More information here: https://web.njit.edu/~gary/202/Lecture6.html https://web.njit.edu/~gary/202/Lecture6.html
- simonh 9y ago
  The resolving power of a 1m scope isn't 100 times that of a 10cm scope. It's 10,000 times as much. Pi d squared. But I think the issue is that with super long time exposures things like lens and mirror aberrations, cumulative drift and rotation over time get magnified as well. As the exposure gets longer, the incremental benefit you get from each unit extension of the exposure decreases. Also, if you take 100x as long to do an observation, that's a hundredth as many observations you can do in any given amount of time.
- gmiller123456 9y ago
  >Are you suggesting astrophotography has physical constraints that non-astro photography does not? No, he's saying the diameter of a lens affects its resolving power. This is due to the diffraction of light bouncing off the lens. Larger scopes have less diffraction due to the laws of physics.
  - CydeWeys 9y ago
    Lenses aren't used in "real" telescopes -- they're made out of mirrors only. Does your explanation still work?
    - gmiller123456 9y ago
      The mirrors in telescopes are still lenses. You're probably thinking of refracting lenses as being "real" lenses. But the parabolic mirrors used in telescopes accomplish the same task. And, yes, diffraction is still just as much of an issue.