[codemonkey (Lee)]

Originally Posted by Amaranthus

How bad (or negligible) is your light pollution? Will you be imaging regularly in moonlight? These are the things to really consider. Narrower bands will reduce extraneous inputs, at the cost of longer integration for the same SNR. I think 5 (or 7) is a pretty good compromise - 3nm is for seriously constrained NB! Heck, I image at 12nm (http://www.astronomik.com/en/photogr...cd-filter.html etc.), but I am in dark skies.

Thanks Barry :-)

I'm in pretty dark skies, on 5 acres halfway between Kilcoy and Woodford, so I'd estimate about 15km to the nearest streetlight.

Imaging when the moon is out would be an advantage, but not 100% required. I'm certain the 5nm would be fine in terms of light pollution.

The main thing I'm not sure about is matching star sizes when processing the images. Will a 7nm Ha and a 5nm OIII/SII match well? Will I have colour halos that are difficult to process out?

Originally Posted by pluto

I did a couple of comparisons when I got my narrower filters here:
http://www.iceinspace.com.au/forum/s...d.php?t=125922
And here:
http://www.iceinspace.com.au/forum/s...d.php?t=126305

Makes a huge difference from my extremely light polluted skies in urban Sydney. Balance wise I went with 5nm Ha and 3nm SII and OIII which definitely made it easier to balance the magenta stars from the SII channel.

Whoa! I'd found your Ha thread this morning but hadn't seen the OIII. That made a massive difference there.