The new T-ring adapter arrived, so once again I can trod out to the backyard and play around in the dark. I decided this night I would spend a little more time with that Barlow lens, maybe I was distracted last time I attempted this when the T-ring failed.
Increasing the magnification, compounds the effects of any errors you might have. I read that on a forum somewhere. It truly is the case. Focusing with a Barlow lens that effectively doubles the magnification, took 10 to 15 minutes! Really had to work to dial it in. This night was particularly challenging. A near full moon was out and monsoon season has officially started, so humidity was up. Any slight fluctuation in the upper atmosphere was readily apparent in the frames I collected.
The following picture of The Ring Nebula (Messier 57) was taken using a 2x Barlow at 1600 ASA, 175 x 15 second frames and automatic dark frame subtraction.
dramatically improved signal to noise ratio as compared to my other runs of 150+ frames in RAW format. It was really no comparison. I'm anxious to try this again in a normal prime focus configuration. For me, I'll use the Barlow approach sparingly where zooming in on a small object seems reasonable.