Filter for OSC [DSO imaging]

Hi @Tareq Abdulla,
I don’t think there is a one-solution-fits-all… Best to check the spectra of the various filters and try to find which light pollution you want to filter out. But to be honest, I tried to to go for the most average LP as I’m not sure what type of lights my neighbours have (all around me have lights in their garden) and then there is the city’s ligh pollution… In the end I went for the Optolon L-Quad, which works well but I don’t think it is any better than the L-Pro (just filters out slightly different wavelengths). Sorry, not much help 

For broadband targets like galaxies, I've gone by the old advice (I have no idea if it's old) that spending the gas $$ to drive to a dark site, with little to no LP is worth the cost of filters. 
Full disclosure: I am still fairly new to deep space imaging.
But when I want to shoot galaxies, I bite the bullet and drive to my Bortle 2 and 3 sky sites. At this point I've been shooting them with no filter, but I'm not convinced that is the best solution either. 
And I do realize that driving 100s of miles is not possible for everyone. Just me 02.$
YMMV, just what I've been doing so far, and it's been working fairly well.
Aaron

Aaron Stratton:
For broadband targets like galaxies, I've gone by the old advice (I have no idea if it's old) that spending the gas $$ to drive to a dark site, with little to no LP is worth the cost of filters. 
Full disclosure: I am still fairly new to deep space imaging.
But when I want to shoot galaxies, I bite the bullet and drive to my Bortle 2 and 3 sky sites. At this point I've been shooting them with no filter, but I'm not convinced that is the best solution either. 
And I do realize that driving 100s of miles is not possible for everyone. Just me 02.$
YMMV, just what I've been doing so far, and it's been working fairly well.
Aaron

When i will have the opportunity i will drive to dark skies, but that is not a lifetime or final solution for me, i still live in city and will have more time in my yard than driving to dark skies, in fact the darkest i can get to will be maybe Bortle 4, if i drive little further i could be at Bortle 3, that is A LOT of drive one way, in fact i will waste more time in driving than imaging, and it is risky always, so i think i better not take that risk that much, not yet, but i have to image in my area first to see, because honestly speaking since they installed those LED streetlights i stopped imaging DSO completely as i was giving up, but who knows, i might get something useable, or it might be a surprise for me, my area isn't fully LP, and that LED lights are only in front of my house by North and nowhere else, other direction sounds less polluted, and if i look to the sky full above by zenith i can see stars clearly.

Tony Gondola:
None of these filters will ever be full spectrum. All of them will require some color correction or color separation, depending on what your goals are for the final image. Overall, up to about bortle 4 or 5, just a UV/IR cut should be fine. As you climb up the scale from Bortle 1 and 2 you'll need longer integration times to get the same SNR. once you get above bortle you will really benefit from wide bandpass filters. Once you're in bortle 8-9, you really need narrow bandpass filters (6-3nm) to get usable data in a reasonable amount of time. Keep in mind that this is general advice as everyone's local conditions will be different. Hope that helps to narrow the field a bit.

It helps although i completely know what you posted long time ago, it just that for OSC people recommended to use UV/IR cut filter at least for stars shape, my camera is coming with AR window, and that will result into bloated stars regardless of LP, there is a reason why some cameras for example ZWO is coming with IR cut window, and sometimes they also giving you the choice about which window to select, i always choose AR window to be flexible and wider bandpass of the camera, but i was thinking about if i will use a filter anyway then if i should just go with a regular UV/IR cut filter [lum] or something that is more suppression just in case.

I have IDAS D2, it helps for LP in the cost of colors as you mentioned, so i decided i will not use it again for color camera but maybe with a mono for more cut off lum, and D2 is like too much suppression, they made sure it will cut more of the blue which result into weird colors to correct, but i don't mind a slight suppression that at least might help or make easier processing, without filters i know there are issues, but why not minimize some of the issues if not all, i mean i can't kill LED lights spectrum, but in my area it sounds it won't kill it all entirely, i still feel the sky isn't %100 polluted by it, even in planetary i use filters to enhance the targets [IR/UV cut or IR pass or UV pass ,...etc].

Tareq Abdulla:

Rafael Amarins:
If you have a fast system F4 or faster the Triband should be a good choice. The L-Pro is a good fit but it depends on the target and PL you're imaging at

I have many systems, fast to slow, so i am flexible, but what that has to do for OSC and filter choice? I mean is the Triband designed for fast optics and it will help overall even slightly?

Reflection nebulae with the Triband will be very dim so you need a faster system for reclection nebulae and galaxies otherwise it will be frustrating. Emission nebula will have a very good contrast. I'm considering you initial question of a "do it all" filter.

I recently made a thread on this topic, linked here. Essentially my argument boils down to:
1. Using a LP filter will alter your color balance (as you know).
2. Depending on a load of conditions, LP filters may actually worsen your SNR (for broadband targets). At best it tends to ~30% reduction in LP, though I expect on average it to be ~10%. Again, this depends on many things and changes from target to target depending on their spectra.
3. The term "LP filter"(or UHC, CLS, etc) is misleading.
4. Best results will be achived with darker skies, though you may be able to get some bright targets (m31, m45) from high bortle with some success.
5. I would recommend against purchasing, but if you already have a LP filter, understand the altered results, and like the image, feel free to use.

And for narrowband filters (in the context of OSC): Effectively all tri/quadband filters return worse results than that of a duoband filter.


So my recommendation would be to tough it out with a uv/ir cut unfortunately. There isn't much you can do in terms of eliminating light pollution beyond changing your location.

Tony Gondola:

Tareq Abdulla:

Tony Gondola:
None of these filters will ever be full spectrum. All of them will require some color correction or color separation, depending on what your goals are for the final image. Overall, up to about bortle 4 or 5, just a UV/IR cut should be fine. As you climb up the scale from Bortle 1 and 2 you'll need longer integration times to get the same SNR. once you get above bortle you will really benefit from wide bandpass filters. Once you're in bortle 8-9, you really need narrow bandpass filters (6-3nm) to get usable data in a reasonable amount of time. Keep in mind that this is general advice as everyone's local conditions will be different. Hope that helps to narrow the field a bit.

It helps although i completely know what you posted long time ago, it just that for OSC people recommended to use UV/IR cut filter at least for stars shape, my camera is coming with AR window, and that will result into bloated stars regardless of LP, there is a reason why some cameras for example ZWO is coming with IR cut window, and sometimes they also giving you the choice about which window to select, i always choose AR window to be flexible and wider bandpass of the camera, but i was thinking about if i will use a filter anyway then if i should just go with a regular UV/IR cut filter [lum] or something that is more suppression just in case.

I have IDAS D2, it helps for LP in the cost of colors as you mentioned, so i decided i will not use it again for color camera but maybe with a mono for more cut off lum, and D2 is like too much suppression, they made sure it will cut more of the blue which result into weird colors to correct, but i don't mind a slight suppression that at least might help or make easier processing, without filters i know there are issues, but why not minimize some of the issues if not all, i mean i can't kill LED lights spectrum, but in my area it sounds it won't kill it all entirely, i still feel the sky isn't %100 polluted by it, even in planetary i use filters to enhance the targets [IR/UV cut or IR pass or UV pass ,...etc].

Unless you plan on imaging far into the infrared, I would always vote for getting the uv/ir sensor glass. It will help to prevent star bloat and eliminates one air to glass surface for broadband targets.

I prefer to add the filter by myself than being added in advance, so using UV/IR cut filter isn't a big deal for me at all, in fact it is so cheap unless i go for something high end name like Astronomk or Baader Optimized one, after all adding a UV/IR cut filter isn't harm in anyway, i can use it as lum with mono if i have to, but it sounds with those what they call LP filters it is always a luck without great success unless it is already darker sky.

andrea tasselli:
Get a L-Pro/ L-quad-band and you'll be sorted insofar as LP broadband suppression is involved. There is vast sea of difference between shooting with or without an LP-suppression (attenuation?) filter which is glaring evident even in my marginal B7 skies. I wouldn't even think about using anything but some very stringent form of spectral band cut-off in B8/9 skies, except maybe for just getting star colors and then maybe not even then...

Did you try under B8/9 for broadband with OSC camera?

I have the same level of light pollution, maybe a bit worse and I can't image shooting naked like that, especially compared to what I can get with a 6nm dual band filter. I've considered taking some broadband data just with us/ir cut with certain targets or to get RGB stars but so far, that's not been very promising.

Tony Gondola:
I have the same level of light pollution, maybe a bit worse and I can't image shooting naked like that, especially compared to what I can get with a 6nm dual band filter. I've considered taking some broadband data just with us/ir cut with certain targets or to get RGB stars but so far, that's not been very promising.

All what i need to do really is just to start imaging back again since 2020, then i can decide if it is so bad or there is a small hope, i will try to do more broadbanding imaging to judge my area conditions then i can see what i can do as gear choices, narrowbanding isn't an issue for me.

Joel Lee:

Tareq Abdulla:

Joel Lee:
I live in B7 bordering B8. I used to use the Antlia Quadband but now I just use my UVIR cut filter. The quadband introduced terrible halos in my images and would cut out signal of some of the fainter, more broadband stuff it was advertised as usable on. If you had to get a LP filter, I’d probably get the L-QEF or something lighter and ensure it does not have halos. However, UVIR cut can be used anywhere and we can use longer integration times in our light polluted cities to help overcome some of these issues. 

Also since you went with the AR window, you absolutely need the UVIR cut. I get terrible UVIR lensing artifacts that look cool once and never again without it.

Ok then, it is decided, UV/IR cut filter it is.

Thank you very much Joel!

By the way, are you from China?

No problem!

I’m from and in the SF Bay Area.

Ah ok cool, thanks for answering.

Alex Nicholas:
My skies are Bortle 4~5 and I honestly rather shoot with a straight UV/IR cut, than deal with light pollution than the colour casts and uneven colour produced by all the available light pollution filters that exists. 
I primarily shoot dark and reflection nebulae, and even though I'm imaging dark targets in light polluted sky, I'd rather extend my integration time than work with data that's had sections of the light spectrum removed from it.

For reference, I use the Player One Anti-Halo 2" UV-IR cut filter and it's been superb and lived up to the anti-halo name.

Sounds i will just go with UV/IR cut then, regardless which Bortle sky i have, even 8/9, ok, then nothing much i can add, i bought that filter you mentioned, buy i think i will buy Astronomik L3 as it has slightly cut off both ends of spectrum, they mentioned it will reduce halo or reduce CA, i don't know if that is true, what is causing halo anyway, CA is achromatic and non APO optics issue mainly.