Focal reducer and AT8RC? Big deal.

There is a precept in astrophotography that should not be overlooked or ignored because some part of your brain is convinced a measure of counterbalance can be applied to the changing of things.

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.

It doesn't Bode well for the new flat...

This latest test of correcting the collimation of the AT8RC demonstrates that it will produce a virtually coma-free image as seen in the image of M81 (Bode's galaxy) below. This is good! However, I screwed up on creating the new flat. My white sheet apparently got loose and I left the camera on high gain (1600 ISO) rather than 100 ISO where it was supposed to be. Doh. Before post-processing, the imaged flat was not what I was expecting. Ran the image workflow anyway just to see. Need to remake the flat.

I suspect though it may not help much as that even with a marginally imaged flat, the previous addition of the field flattener had significant impact on post-processing out the uneven signal levels due to optical curvature.

So, before reverting back to using the flattener lens, I will take another round using a deep sky filter for comparison.