Quote:
Originally Posted by Atmos
The most important difference between the 3&5nm Ha filters is the NII emission line. A 3nm Ha has only the Ha emission while 5nm+ will also contain the NII emission. With the extra emission it will bring make some objects brighter but it isn't a "true" Ha filter.
|
Thanks for that. Yes I knew that and its why I decided for my Honders not to switch to 3nm at my dark site on the advice of Don Goldman. But my home site, whilst fairly dark, does have some easterly pollution and I wonder how much of a gain you get from the 3nm. They are very expensive.
3nm narrowband filters seem to be used on this site often with the QSI683 as 30mm filters are far less expensive than the 50mm square ones.
Greg.