Some advice- what sort of noise is this?

[pyrasanth]

If I use a HA filter with a bright moon as it is tonight or yesterday I get a very grainy background image which is very difficult to correct. I know that the Baader HA filter I have is probably 7-8 nm so it's not the best as far as narrow band pass goes but I've heard elsewhere that it is a good filter. I'm also told we should image in HA to reveal HA detail & not remove light pollution or noise so perhaps I'm expecting too much!

I'm trying, however, to identify the source of thew noise captured- might it be scattered light in the atmospheric dust caused by the bright moon? or should one not image when the moon is bright as I'm pretty sure the moon has a hand in the noise captured. An image is shown below of M82- 15 minutes in HA & if I lift the brightness on the original the noise looks like a blanket of sugar grains all over the image- not good.

What do you guys think or advise- new Astrodon 3nm filter or don't bother when the moon is bright or simply bad seeing on the night the image was taken. All opinions gratefully discussed. The image has no flat field correction, Bias or dark applied so is pretty much as it is captured.

The image is below:

[steppenwolf]

Narrowband filters make it possible to image under full Moon conditions but they certainly don't guarantee a great result as there will always be gradients to contend with if nothing else!

I think that part of your problem (in addition to the Moon!) in this image is high altitude moisture.

[johnrt]

What Steve said, even the narrowest of Ha filters down to the 3nm Astrodons aren't moon proof when it's as bright as it is tonight.

Personally I sit out any clear nights either side of a full moon when it's 80% or above illuminated.