Coma Corrector

[mick pinner]

could anyone recommend a good coma corrector to suit an f/5 newtonian and what if any problems does one introduce to the focusing ability of the scope?

[Gama]

I have the Baader MPCC Coma Corrector.
My scopese a 22" f4.5, and in viewing terms, it does wonders on the cheaper eyepieces. But on my expensive lenses not as much, but there barely any coma that i could see before. So a good quality eye piece really does make a difference.
For imaging, then the buck stops here. It reduces the coma very well, and i was very happy with the shape of the stars at the edge of my CCD APS sensor.
Threads to the bottom of most eyepieces, plus also has T threads on it as well which screws right on a T-mount or into a CCD camera. Spacing required is only 55mm from the edge of the last lens to the corrector.
Oh yeah, best of all it does NOT increase or decrease your f ratio like the teleview corrector or others. Plus its 2" and not a 1.25 corrector.