Guided learning / 4 lessons
Understand the light you collect
Follow an image from telescope optics to photon noise and stacking.
Where this takes you
Explain what your optics control and why accumulating exposures can help an image.
Follow the lessons ↓Lesson 1
Aperture and resolving power →
Start with the light gathered by an aperture and the detail it can resolve.
Pause and consider
Which limits come from the instrument, and which could still come from the atmosphere?
Lesson 2
Focal ratio and image scale →
Connect your telescope and camera to the scale of an image.
Pause and consider
Find your focal length and pixel size if you know them. What else would you want to know before choosing a target's framing?
Lesson 3
Photon noise →
Understand why repeated measurements of light vary.
Pause and consider
Explain why collecting more photons helps even though the photon count still fluctuates.
Lesson 4 / Interactive figure
Signal, noise and stacking →
Connect individual exposures to a combined image.
Pause and consider
What assumptions sit behind the square-root improvement, and what problems would stacking alone fail to fix?
Put it into practice
Read a photograph as an observing record
Open an image in the archive. Inspect its acquisition information and image study where available. Note which details are supplied, which remain unknown and what you would record for your own session. Worked examples are labelled.
Study a photograph →