The OWB filter would usually not be designated as an "astronomical" filter. The intention is to enable converted DSLR cameras (without inbuilt IR-filter) to be used for 'terrestrial' photography.
The OWB (Original White Balance) filter shifts the complete spectrum of a converted DSLR in such a manner that the camera will not be exclusively usable for astro-photography. Therefore the decision, which in former times had to be made, whether to 'victimize' a DSLR in order to exclusively use it for astronomical tasks or accept the lower sensitivity on the red end of the spectrum it is now a thing of the past.
The OWB EOS Clip filter is available in normal APS Clip filter size and also in this XL version designed for full frame format Canon DSLR's
The Astronomik OWB (Original White Balance) filter shifts the complete spectrum of a converted DSLR in such a manner that the camera can be use for normal daylight photography.
The Astronomik OWB EOS XL Clip filter is designed for use in Canon DSLR cameras with full frame (35mm format) sensors. It cannot be used in APS cameras
Main Use
DSLR cameras which have been converted for astronomical use by removing the inbuilt IR-filter or by substituting it with a filter with greater range for H-alpha, have a white balance that made them unable for 'terrestrial' purpose. The spectral sensitivity of the DSLR will be changed by an OWB-Filter to the former range. In other words: The OWB pretends to be the conventional built-in filter!
Suitability