For some time I have been making changes to get the very best out of my OGS RC-10 specifically for the viewing of globular star clusters. In 2017 I snagged an excellent NVD Micro with great response in the far red where the giant stars of these objects shine brightly. In 2018 I added the Baader BBHS diagonal that also has remarkable reflectance at these wavelengths. This year I was rounding out my Sky 90 system with the purchase of Takahashi's Extender-Q 1.6 X lens system. It occurred to me that this optic is just what I was looking for to get the RC-10 to 140X and a 17' FOV. I have tried a variety of approaches to achieve these results over the years. J. B. Sidgwick states that to achieve full resolution of a telescopic system you need 13 times the objective diameter in inches and this arrangement gets me there. Under these conditions my system is operating at f/15 and the Micro handles this effortlessly.
During the last new moon I had a stretch of uncommonly good evenings so I was able to try it out. The results way exceeded my expectations. Major clusters like M14 and M92 present themselves perfectly in this FOV and have an incredible depth to them as exceptionally faint stars are clearly displayed and separated from their neighbors. Faint clusters similarly are now routine objects that show detail and extent that I have come to expect from their brighter brethren. Perhaps the best example of all this is NGC 6749. With my old equipment I described this cluster as a 4' glow with about half a dozen stars resolved. With the Micro alone I was able to increase this to a dozen. My last outing, which had a really wonderful clear and stable sky, showed so many stars that I quit counting at three dozen!
Recently I posted a comment on my observations of NGC 6229 with this new system over on the deep sky observing site. It similarly describes more stars and better resolution than I have ever obtained before.
My job now is to re-observe the 100 clusters I have seen before in this new light.
Edited by chemisted, 14 September 2019 - 09:54 AM.