My usual filter on the Hyperstar 4, on a C11, with an ASI 2600MC Pro CMOS camera, is a simple UV/IR cut filter. And this does the job admirably. But in my Bortle 4.5 zone I would like to filter out some of the background rubbish and get even more performance out of the Hyperstar.
To this end, I have tried an Optolong L-Enhance filter which filters in the H-alpha and OIII and filters out the rest. Doesn’t seem to help the Hyperstar much as far as I can see, which just means the filter is not good at f#2. Not too surprising really, and pretty much as expected. However, I switched it over to the Canon 200mm prime lenses where it would provide an f#4.2 aperture – and the results are superb. Win some lose some.
Just seen that Starizona also sent me an Optolong L-Extreme filter as well. As I haven’t tried this out on the Hyperstar yet, I just fitted it this morning. I will do a test run on an object where I already have plenty of UV/IR cut filter data to compare it with (probably the Pelican nebula) and I will get back to you with the results. I am expecting that, once again, the results are inferior to a plain UV/IR cut filter, but you never know.