# Explain how the invention of charge-coupled devices (CCDs) improved astronomical observations compared with using photographic film.

> AQA A-Level Physics (7408) — 3.9.1 Telescopes · Explain · 5 marks

## Mark scheme (5 marks)

1. CCDs are more sensitive to light than photographic film
2. CCDs can detect a greater range of wavelengths / frequencies (including infrared and ultraviolet) compared with photographic film
3. CCDs produce a digital (electronic) image that can be stored and processed by a computer
4. CCDs are more efficient / have a higher quantum efficiency — they record a higher proportion of the light that falls on them compared with photographic film
5. This means shorter exposure times are needed / fainter or more distant objects can be imaged

## Key terms

- [photographic film](https://www.gradenine.co.uk/glossary/photographic-film)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-invention-of-charge-coupled-69c1a231) · Published by Druglandscape Ltd.