What is this astounding precept?
That for every new optical surface added into the optical train, the quantity of available photons is reduced.
Translation: the more optical junk you put in the way, the less light you are going to collect. Period.
Such is my experience with using a focal reducer with my telescope. Frankly, the output was less than I expected for the money spent. Though this attempt included a deep sky filter as well, the additional filter served to put an exclamation point on the less than fulfilling result.
Yes, the subject of this image is beautiful. That is God's handiwork, not mine. My contribution comprises the harsh cutoff of the darkness and less than brilliant stellar backdrop.
So in reducing the number of optical surfaces, choosing the filter over the focal reducer my choice. For those of you thinking about a focal reducer for your AT8RC, your time and money might be better spent simply focusing on increasing exposure and integration time.
...now, I just need to create some new darks and flats to go with this filter, and we shall see how things improve.