Just wanted to post some information on using the Baader (multi purpose) Coma Corrector on my F4 Astro-Tech 8" Newtonian.

I've been hearing (from telescope dealers themselves) that some coma correctors do a very poor job of correcting coma in fast Newtonians. Some also increse the focal length and therefore the F Number. For those of us that don't guide, the F Number is king. I don't want to lose the edge that F4 gives me. For this reason I chose the Baader Coma Corrector, as it specifically states it does not increase focal ratio.

Image 1 is the corner of an image of M31 taken with my F/4 Newtonian without any correction.

Image 1

This is the bottom right corner of an image of Andromeda

You can see the stars around M32 are blurred and

enlarged.

Image 2 is a later image of Andromeda with the Coma Corrector in place.

Image 2

This is a similar region of a later image of Andromeda.

This was taken with the same equipment as the

first photo - but with the coma corrector attached

to the DSLR

In Image 2 with the coma corrector in place, not only are the stars in the corner of the frame fully corrected, but some stars are visible in the cloud of M32 which are invisible in the first image. The difference in orientation is due only to the DSLR being oriented differently on the telescope and not to any change in focal length. This coma corrector can be fitted to eyepieces with additional T2 rings. I'm not concerned with this, my requirement is that images are corrected for photography. I therefore leave the corrector attached to my camera's T-ring. I simply fit this assembly to the camera for imaging.

I bought this corrector new for $149 USD. A good deal in my opinion.

Thanks for reading.