Light pollution filter for galaxies

[Endolf]

Hi

I got myself an IDAS LPS D2 to try and combat some of the light pollution in my area, I got the D2 because we have some LED street lighting. I'm hoping on some of the nebulae this will help with the backgrounds.
I gave it a quick try on Markarian's Chain last night, just as an experiment, and unsurprisingly it filtered out too much of the useful data too.
Does anyone have any suggests for a OSC LP filter, preferable that is available in EOS clip format, that doesn't affect galaxies?

Thanks

Edited April 5, 2020 by Endolf

[geordie85]

Are you sure it filtered out data? I only ask as the moon being so bright and close will of had a massive, negative impact on your images. 

I'd suggest waiting until the moon is out of the way and try again. 

[alacant]

1 minute ago, geordie85 said:

Are you sure it filtered out data?

Hi. Yeah. You best me to it:)

53 minutes ago, Endolf said:

doesn't affect galaxies?

Maybe post -a link to- your image? Then we'll be able to answer more accurately. A quick try on faint galaxies isn't really possible; they take hours. With the moon also, even more hours e.g. this was 4 hours with the gibbous moon on Friday. It still needs more.

HTH.

[Whistlin Bob]

Very much in agreement with @geordie85 and @alacant, but to encourage you further, I found the D2 to be  a very good LP filter. I bought it after an 8m LED streetlight was fitted right outside my house and had thought the imaging part of my hobby was over.

The picture below was taken with a modded 600d and the IDAS D2 (on galaxies I don't think the mod'ing makes so much difference) this time last year.

[Endolf]

Ok, by quick try I mean 2 hours of data. Having filtered out some frames with poor star shapes I got down to about 80 minutes of data. Here I've exported 2 sets of data as they fell out of APP, the first one is from March 25th, and was 2640s integrated exposure the second is from last night and is 4920s integrated exposure. Flats, darks and darkflats were present for both images. The first one used APP to remove the light polution, the second used the filter. The subs were so dark I had issues framing the images up.

I took some single subs of M101, M81 and C/2019 Y4, just to compare to single subs from previous sessions, C/2019 Y4 seems to be better with the filter, although the original was taken on the 26th March, so the object is brighter so not a fair comparison. M101 and M81 were more difficult.

Both 120s subs

Maybe it was just due to the moon. The fact that other people have had good success with this filter on galaxies is good to note. I'll try and gather some more data (weather allowing) and see how it goes.

Thanks.

[The-MathMog]

From the dates you just stated, yesterday and the 25th of march, I would say that the moon is definitely the dominant factor here, and that you can't use the comparison there.
The moon as it is, is nearly full and will significantly brighten the sky, hiding a lot of details of faint galaxies. Back at the 25th, the moon was under the horizon basically the whole night.

So I would say, wait until the moon is crescent and/or below the horizon, and then try again

I've heard a lot of good things about this filter too, so give it another go