The thirst of fast reflectors to gobble up ever greater swathes of the night sky means that wave fronts sometimes have a challenging time arriving at the same plane of focus. This is a minor but irritating consequence should you wish to enjoy aberration-free starlight across the entirety of the observing or imaging field.
Yet the photons travelling trepidatiously down the tube need not worry. For just as they jostle for position on reaching their focus, this high resolution coma corrector comes to their rescue.
Designed for rich-field telescopes down to an amazing f/3, the emerging beam comes to a halt at a flat field 30mm in diameter, extending the focal length by only six percent in doing so. Suitable for both visual and photographic use, it requires only 32mm inward focus travel for the former and for the latter extends the focus by 35mm – exactly where a camera needs it.
Delicate adjustment is provided by a graduated helical thread.