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Glossary | Telescope accessories | General | Series | H-Alpha 6Nm

Filters with a low half-width for hydrogen nebulae

The filters in the H-alpha 6nm series are suitable for photographing hydrogen nebulae. The contrast between objects that emit H-alpha light and the background sky is greatly enhanced.

The full width at half maximum of 6 nanometres is perfectly suitable for use with cameras with particularly low dark current.

6nm filters are the best choice if you are observing from a location with extreme light pollution or photographing faint objects in regions of the sky with many stars.

Transmission curve

Transmission curve

What does CCD mean?

CCD filters also feature an integrated IR block. This is particularly important for photography, since although the camera sensors are sensitive to this long-wave spectral range, the upstream optical instruments (telescopes etc.) cause imaging errors in the infrared range.

Such optical errors do not play a role in purely visual observation, since the human eye anyway cannot perceive them. Of course, if you specifically want to shoot in the IR spectrum, you should not use a CCD filter.