CCD cameras of G2 series can include integrated filter wheel for 5
filters up to 31 mm diameter. So changing
of filters between exposures can be performed programmatically,
without the user's intervention. Camera can interleave acquisitions of
individual R, G and B images, for instance to eliminate influence of
changing light conditions, height of object above horizon etc. But the
number of filters in internal filter wheel is limited to five.
While it is often enough to accumulate several tens of minutes of
exposure for each color channel to obtain good image of many objects,
and so it is possible to get the whole exposure during one night,
exposures for narrow-band imaging (typically in wavelengths
corresponding to SII, H-alpha and OIII lines) must be much longer. The
it could be possible to combine LRGB filters in internal filter wheel
with narrow-band filters in the form of clip-filters. When an exposure
through single narrow-band filter takes whole night, automatic filter
exchange is not that necessary.
G2-8300 CCD camera EOS adapter for clip-filters
Because of clip-filters dimensions (they are rectangular with
approx. 27 × 22 mm size), they are limited to G2 series of CCD
cameras only. It is not possible to use them with large-sensor cameras
of G3 and G4 series.
Inserting of clip-filter int the adapter (left) and G2
camera with the filter on place (right)