Quote:
Originally Posted by John K
The question I was really asking is if 7nm works effectively from severely light polluted skies for narrowband vs 3nm? I live in Brunswick which is 5.5km from Melbourne's CBD.
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Hi John,
I have used 12nm for some time and then gradually over time upgraded to 3nm due to heavy light pollution - I image from a very close proximity to Brisbane's CBD. The difference was astounding. If you have severely light polluted skies, then 3nm will give better contrast and detail than 7nm filter, or even 5nm filter. Such narrow filters will also lessen the effects of the moon light. To me it was no brainer. 3nm filters are relatively expensive, but with such filters you know you are collecting the best data you can from your site and with your gear.
Maybe 5nm Ha filter would yield comparable results to a 3nm one due to inclusion of nitrogen emission line, but in severely light polluted skies 3nm might be a better option. Oxygen and Sulfur - 3nm will yield higher contrast than filters with wider bandwidths, unless one is using a very fast system (under about f/4).
IMO the importance of filters in astrophotography is too often underestimated. Just my five cents
