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Equipment buying guides

Astronomy cameras — match the sensor to the sky

Sensor dimensions and focal length set the framing; pixel size affects image scale. Megapixel count alone does not describe suitability.

Planetary work favours fast capture, while long-exposure deep-sky imaging usually benefits from controlled cooling and calibration.

Objective lens · Sensor and image field12
  1. 1Objective lens
  2. 2Sensor and image field
Functional schematic, not to scale. Rays and component shapes are simplified; this is not a particular model’s optical prescription.

What is it good for?

Recording images unlike the direct eyepiece view, plus measuring and processing signals across frames.

Limitations and trade-offs

Large sensors need an adequate image circle and filters. Cooling cannot replace integration time, focus or tracking.

Check before buying

  • Sensor field and pixel scale
  • Read noise, cooling and recording modes
  • Drivers, power and backfocus

Compare the whole optical train, not just the sensor model in a specification list.

Matching your setup

First check that the target fits and the optics illuminate the sensor adequately. For small angles, field width in degrees is approximately 57.3 × sensor width / focal length, using the same length units.

Image scale in arcseconds per pixel is about 206.265 × pixel size in µm / focal length in mm. For example, 3.76 µm at 500 mm gives about 1.55″/pixel. Finer sampling cannot arbitrarily overcome atmosphere and optical resolution.

Check raw-data recording and calibration. Stable temperature makes repeatable darks easier, but appropriate flats and optical-train checks still matter. Allow for storage requirements and computer performance too.

Documentation and further reading
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