Glossary | Telescope accessories | General | Series | Narrowband
Line filter with 6.5 nanometre full width at half maximum
The Narrowband series offers line filters with a full width at half maximum of 6.5 nanometres, recommended for optical systems with an aperture ratio of f/10 to f/3.5.
Most telescopes used by amateurs fall within this wide range of recommended aperture ratios. The full width at half maximum is also suitable for optics with a smaller aperture and represents very good value for money.