@afb67fcd Very tempted to send my little ef-m body in to have he filter removed, looks great!
@3225906e definitely worthwhile if you don't want to use the camera for mainstream photography. I'm using a 720nm red filter which works really well.
@afb67fcd tThe lens system may now be obsolete (Canon says it isn't but you can't buy new bodies anymore), I have a spare m100 doing nothing so it seems like a good option. It was a surprisingly good little astro camera.