Don't mean to hijack your thread Mark but been reading the links you have provided and there is some good info there so figure I will keep this going.
What are peoples thoughts on these two filters?
http://www.ebay.com.au/itm/Optical-F...ht_1115wt_1144
Anyone know if this OIII Line Filter is only designed to be used for imaging? Reason I ask is because it doesn't really mention visual use in the description but it mentions CCD use. Really want a good Line Filter.
Also...
http://www.ebay.com.au/itm/Filter-48...item518bd1e3bc
Interested in this Narrowband filter that Alex (mental4astro) put me onto. Not really doubling up on filters am I?