The bright Newtonian telescopes are among the most popular instruments for astrophotographers. However, their optics - regardless of the manufacturer - have one "annoying" defect, namely coma failure.
Coma: the enemy of bright Newtonian telescopes
The imaging of Newtonian telescopes gradually deteriorates from the centre of the field of view outwards, i.e. even with the best focusing, stars at the edge of the field of view will not be point-like. This phenomenon can be very disturbing in photographs taken with the brighter Newtonian telescopes around f4-f5.
Solution to coma failure
What is the solution? Using a SkyWatcher coma corrector can significantly reduce coma error: simply place it in front of your camera when taking photos and enjoy stars dotted right up to the corner of the field of view. In addition to the camera mount, you will also need a custom Canon or Nikon intermediate ring with M48 thread. The coma corrector fits into a 2" focuser.
The outstanding feature of the SkyWatcher coma corrector is that it reduces the focus of the telescope by about 10%, making it even brighter.
