Allan,
I'm using 5nm filters but just shelled out for a 3nm Ha and OIII. In 50mm square format they are bl**dy expensive! At least I'm saving on shipping by picking them up on my next business trip to the US
SGPro is certainly very capable and getting better all the time. I started using ACP before I had heard of it. At some stage I may have to consider switching. Plate solving is a godsend in any program. I don't know how I lived without it!
Cheers,
Rick.