Hi Frank,
For that particular shot I was using the QHY168C with the STC-Duo "Narrowband" Light Pollution Reduction filter. The Coma Corrector was the SkyWatcher Quattro 4 element CC which slips right into a 2" focuser tube of the Moonlite. I use a Baader Vari-Lok 29 adjustable extension tube with the setup as well, it is screwed into the attachable rotator piece QHY sends with the 168C camera and screwed onto the t2 adapter piece that fits on the Quattro Coma Corrector. I get the best corrections @ a 55mm +/- .5mm from the sensor face to the the CC lens. I also had a Tele Vue Parracor 2 I had tried with the 12" F4 Quattro prior to getting the SW Quattro CC, but it did not do as well for me as the addition of the SW Quattro did. Can't pin point why the SW CC did better than the Tele Vue, I had the Tele Vue with my somewhat improved Orion 10" F3.9 Newtonian and it did great!!
I have the QHY163M as well with the Xagyl 7 place 36mm unmounted filter wheel, and while I have not tried it yet I could see where trying to get an OAG in the imaging train while maintaining some proper spacing between the CC & the Sensor could be a bit dicey. Haven't used the 163M with the 12" Quattro yet, but will sometime when there are more nebular objects on my list. As for attaching the FW would be about the same as for the OSC 168c, except for FW to 163m camera standard front flange, corrector to spacer, spacer to FW. If I remember right I only needed an extra 7mm of spacer from the FW to the CC to get to the desired 55 - 56mm total from sensor to CC with the Xagyl wheel in place.
Another note on the !2" SW Quattro OTA I would mention is the topic of collimation. It takes a quality collimation tool or tool set to get the collimation on this or about any other Newtonian design OTA in the 10" "fast" & above aperture range tuned in well. You're not going to get by well with a simple laser or cheap peep sight or 1.25" Cheshire eye piece. I went with the Cat's Eye 2" TELECAT XLTM + INFINITY XLKP set when I got the 10" Newtonian... It works beyond great for the 12". I just use the original center ring the OTA came with instead of the CatsEye replacement, the original center marker works great for me. It really does give you perfect collimation, as well as for me revealing quickly any imperfections in your entire focuser tube to secondary, secondary, spider, and primary alignments. Allowing you to get ...Everything... tuned in and lined up the first time fairly quickly. After that it's a snap to do a quick check and any minor corrections that might be needed on your mirrors.
A side note on the Light pollution filter I use: I tried the STC-Duo for a bit, then did a couple of head to head comparisons of the STC Duo to the Astronomiks CLS-CCD LPR filiter because it seemed to me the CLS-CCD was dong a better job of picking up more faint dust and gas than the Duo while still reducing the LP just as well or better when using them at the same imaging light frame timings. I went back to the CLS-CCD, the filtering graphs for the wavelengths of light are pretty much the same, but with my older Canon Hutech Modified 40D and now the new QHY168c the Astronomiks filter just gives more faint detail than the STC-Duo.
Astronomiks CLS-CCD LPR Filter:
http://thestardeckobservatory.com/piwigo/picture.php?/245/category/29STC-Duo NarrowBand Filter:
http://thestardeckobservatory.com/piwigo/picture.php?/246/category/29I will likely do a couple more comparisons of some of the Summer Objects (Nebula), but from another outing the results were similar, however both nights on that outing the sky conditions were fairly unstable.
Mark
CS!