Filter wheels are used with monochrome cameras to create RGB sequences for deep sky and planetary imaging. Some filters have a min of 5 slots for RBG and luminance filters, but also infrared pass filters for high resolution imaging. Other filter wheels have more slots for narrowband filters and combine the RBG with SHO (sulphur, hydrogen and oxygen).
Nowadays, filter wheels can also be used with colour cameras combined with infrared pass filters, H alpha filters to boost the signals of nebulae and multiband filters such as Optolong L-eXtreme and L-eNhance.
Filter wheels can accept different filter formats, the most common ones are 1.25", 31mm, 36mm, 2" and 50mm. The installation of the filters in all cameras is easy and only need to be done once.