Chris Kitting and I converged here for a night whose prime directive was to record the conjunction between Comet Holmes and the California Nebula. I also wanted to test out some options with my 100mm lens on the ST2000XCM. This combo gives blue halos around bright stars and I suspect it has to do with either the far IR leak in the SBIG IR/UV filter, or perhaps a UV leak shortward of the published transmission curve cutoff. I wanted to try adding in series my 49mm UV/Haze filter from my OM-1 setup. Just before closing up, I also tried adding a third filter; Chris' "high altitude UV/Haze" filter which supposedly blocked more of the UV. None did a satisfactory job of fixing the problem. All the images below were shot with the 100mm Zuiko lens and SBIG UV/IR filter plus Hoya UV/Haze filter.
The Jellyfish Nebula and M35. 9x5min stack in Registax 4, after dark subtract and flat fielding. Cropped, and the usual Photoshop CS2 / Astronomy Tools adjustments. Some tilting in the focal plane added to the UV leak problem. And, some warping appeared with the last two frames which had yet a third UV filter stacked on, so the stack isn't perfect. Not a great photo, but it is what it is...