Quote:
Originally Posted by Paul Haese
Kevin if I am using a 5nm filter is there not a chance of some Hb seeping in? I thought that unless I was using 3nm filters then some Hb is still captured. Am I wrong in thinking this?
|
You won't get any Hb, Paul. As Kevin said, that's way down in the blues. A 5nm Ha filter will also get NII however, and there is often some of this about. Ha has a wavelength of 656.28nm and NII is at 658.36nm. A 3nm filter cuts out the NII as I found to my chagrin when imaging the Helix. A 5nm filter would have got me combined Ha+NII data and delivered good SNR much faster...
Cheers,
Rick.