Another project with a Samyang 135 and an RST-135 that I'm proving out for mobile use.  I am quite pleased with this rig and wanted to do a little bit better than my initial first light image of Lower's Nebula just completed.  Like anything, there is always a little bit of a learning curve and hopefully I've made a little improvement. 

I am using the ASI183mm with it's small pixels to get as good of a sampling rate as I can and decided to go full on narrowband for this image.  The project did include the idea that I wanted to see how the RST-135 would perform with longer sub-exposures.  So this one included only Hα and OIII data at 5-minute exposures.  I'm happy to say that the RST-135 handled the longer exposure very well and I only tossed a few exposures whose issues were not tracking related.  I have to say, very impressed with the little mount.

I did this work with the aperture set at f/2.4, (if that is the value at the detent between f/2 and f/2.8 ) and let it rip for a night with each filter. 

Processed this in Pixinsight, again using Frank Breslawski's bi-color narrowband processing scheme but really worked on the color a lot more.  I do subscribe to the notion that when working in narrowband, there is some license "allowed" with respect to the final color palette.  Thank you again @Frank Breslawski , I have learned so much from you and really appreciate your generosity.

I am fairly pleased with the result and I think with a little more work, this can really be nice to use for the big targets out there.

However, one thing did occur to me...  Once I stacked the sub-frames, I would have thought the resulting images would have been brighter.  5-minute exposures at f/2.4 should be like 6x faster than imaging at f/7, right?   So I did have to work a bit to bring up the signal during post processing.  I am using standard NB filters at this fast focal ratio.  Perhaps high speed filters allowing for the band shift might be the thing to do to get the best out of the lens.  If anyone has thoughts on that, I would love to hear them!

Anyhow, thank you and I hope you like this one...  Clear Skies and Good Health!