The focal reducer that I use is a Meade f6.3 one that screws onto the back of the SCT tube. It does clearly reduce the time required to image an object, but it does make the image smaller, and introduces severe vignetting which has to be dealt with if you want the pictures to look "nice".

To the right is an image of the sky taken through the 8" Classic, with a white transparent mask over the front of the corrector plate. This is a 300s exposure taken at ISO800. The vignetting is obvious, as is the sodium light pollution......I use masks like this to correct my photos, although it is not entirely satisfactory. A darker sky would be much better.

What I found more worrying were the reflections that can be generated by the additional optics, as can be shown in the picture to the right. This is a picture of the Horse Head which can just be seen (it is taken with an unmodified Canon 350D which is not particularly sensitive to the H-alpha). The vignetting and light pollution were particularly hard to cope with in this image, and I do not have a processing answer for an image this bad.

However, this was the first time that I observed the Horse Head which I found exciting, I was not even sure I had got it in the field of view when I started this sequence of exposures. To observe the Horse Head was the goal of this exposure so from that point it was a success.

As a side note, I have also had bad reflections in the past when using an off axis guider. These have come from bright stars caught on the edge of the prism, so you have to exercise care with these also. You can not always see the reflections in a single image, they can "appear" as you sum multiple images.