Filters in a Bortle 2 (nearly Bortle 1) Site - Forums

Topic starter

Jun 29, 2023 · Edited: Jun 29, 2023

I'm heading to a dark sky site in a few weeks and want to image a cluster, an area of nebulosity and maybe a galaxy. Exact targets are being determined. My question is which filters should I think about using under such conditions? I have the L-Pro broadband, L-Enhance narrowband, and an L–Ultimate narrowband filter.

I'm using the ASI2600MC OSC camera and would like to get some sulphur as well as O and H if possible. I wonder if anyone has used the Askar SII 3nm filter with an OSC camera? On the other hand, the reason I went the OSC route was to not have to deal with changing filters, multiple flats, 3 or 4 times as many subs, etc. So if I'd prefer not to have to change filters while on a given target, I am guessing the next-best thing would be to try and get the colors I want in processing, which I am already learning to do.

I'm used to using filters in a Bortle 7 sky, so this is why I am asking..

Thanks for sharing your experience with me, much appreciated!

Jerry

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andrea tasselli

Frequent contributor

Jun 29, 2023

If broadband target: None
If emission lines target: L-Ultimate

AstroRBA

Jul 3, 2023

Hi Jerry,

I use the 2600MC on an Esprit 100 (and a few other scopes) for dark site travel (B1 to B4) and I ditch the filters completely (provided that there's no significant moon phase); enough data and PixInsight and you'll have great colour data in my opinion.

Good Luck!

Pete

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Jerry Gerber

Topic starter

Jul 3, 2023

Hi Jerry,

I use the 2600MC on an Esprit 100 (and a few other scopes) for dark site travel (B1 to B4) and I ditch the filters completely (provided that there's no significant moon phase); enough data and PixInsight and you'll have great colour data in my opinion.

Good Luck!

Pete

Thanks Pete, that's helpful to know..

Alan Brunelle

Jul 3, 2023 · Edited: Jul 3, 2023

Odd, but I too am heading to a dark site in a couple weeks. Maybe I will see you there!

In "theory", the L-Pro would not really interfere with signal from any emission nebulae, since it has its best transmission broadly around those already. But its passing of those bands is not 100%. So it would reduce you signal the slightest bit. At Bortle 2 and 1, there really should be no benefit. And any extra glass can introduce refractive aberrations, however unlikely. On the other hand, there can be some fluorescence due to aurora and stuff like that, but that should be negligible at low latitude, though it is a very active sun. And remember, aurora glow is pretty much the same bands as what we see in emission nebulae, but favoring Oxygen and Nitrogen. So the filter won't do much in that case.

I am such an L-Pro addict that I never take it out. Probably because I do most of my imaging at home in a Bortle Low 4 zone, but with some light domes. And with a RASA, if I take the L-Pro glass out of my light path, I have to replace it anyway with another clear glass element. When I go to New Mexico in a couple weeks I will probably take out the L-Pro. But wait! I would then be left without an IR and UV cut, which the L-Pro works as. If your camera has those cuts built in, then no worries. For me, the L-Pro never has seemed to skew my colors with either of my two OSC cameras. But then I have not gone without much either. Either way SPCC seems to solve all issues.

Enjoy your trip!

Alan

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Jerry Gerber

Topic starter

Jul 3, 2023

Alan Brunelle:
Odd, but I too am heading to a dark site in a couple weeks. Maybe I will see you there!

In "theory", the L-Pro would not really interfere with signal from any emission nebulae, since it has its best transmission broadly around those already. But its passing of those bands is not 100%. So it would reduce you signal the slightest bit. At Bortle 2 and 1, there really should be no benefit. And any extra glass can introduce refractive aberrations, however unlikely. On the other hand, there can be some fluorescence due to aurora and stuff like that, but that should be negligible at low latitude, though it is a very active sun. And remember, aurora glow is pretty much the same bands as what we see in emission nebulae, but favoring Oxygen and Nitrogen. So the filter won't do much in that case.

I am such an L-Pro addict that I never take it out. Probably because I do most of my imaging at home in a Bortle Low 4 zone, but with some light domes. And with a RASA, if I take the L-Pro glass out of my light path, I have to replace it anyway with another clear glass element. When I go to New Mexico in a couple weeks I will probably take out the L-Pro. But wait! I would then be left without an IR and UV cut, which the L-Pro works as. If your camera has those cuts built in, then no worries. For me, the L-Pro never has seemed to skew my colors with either of my two OSC cameras. But then I have not gone without much either. Either way SPCC seems to solve all issues.

Enjoy your trip!

Alan

My OSC camera has IR cut built into it. I'll probably image this time (Bortle 2, close to Bortle 1) without any filters..

Matija Jakičević

Jul 3, 2023

Jerry Gerber:
Alan Brunelle:
Odd, but I too am heading to a dark site in a couple weeks. Maybe I will see you there!

In "theory", the L-Pro would not really interfere with signal from any emission nebulae, since it has its best transmission broadly around those already. But its passing of those bands is not 100%. So it would reduce you signal the slightest bit. At Bortle 2 and 1, there really should be no benefit. And any extra glass can introduce refractive aberrations, however unlikely. On the other hand, there can be some fluorescence due to aurora and stuff like that, but that should be negligible at low latitude, though it is a very active sun. And remember, aurora glow is pretty much the same bands as what we see in emission nebulae, but favoring Oxygen and Nitrogen. So the filter won't do much in that case.

I am such an L-Pro addict that I never take it out. Probably because I do most of my imaging at home in a Bortle Low 4 zone, but with some light domes. And with a RASA, if I take the L-Pro glass out of my light path, I have to replace it anyway with another clear glass element. When I go to New Mexico in a couple weeks I will probably take out the L-Pro. But wait! I would then be left without an IR and UV cut, which the L-Pro works as. If your camera has those cuts built in, then no worries. For me, the L-Pro never has seemed to skew my colors with either of my two OSC cameras. But then I have not gone without much either. Either way SPCC seems to solve all issues.

Enjoy your trip!

Alan

My OSC camera has IR cut built into it. I'll probably image this time (Bortle 2, close to Bortle 1) without any filters..

I have an omegon veTEC533c pro and it has a an uvir cut installed into it and I've been imaging with it with no filters in bortle4 with no issues. I just captured the Cygnus Wall in broadband and it wasn't hard to control, especially with AI tools such as graxpert and blurx.

What I'd suggest is get a good uv/ir cut if the one in the camera isn't , but if you can't you'll be fine with the preinstalled one. When stacking (pixinsight) make sure to stack rgb channels separately and later combine them to fix star color aberration with an osc.

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Brian Fulda

Jul 3, 2023 · Edited: Jul 3, 2023

@andrea tasselli If broadband target: None
If emission lines target: L-Ultimate

Lots of convoluted replies but this simple answer sums it up.

Your chosen filter should depend on your target, no matter which Bortle zone you shoot from.

And yes, a narrowband filter like the L-Ultimate isn’t just for shooting from light pollution. As Andrea said, if your target has some emission or planetary nebulae in it, then a narrowband filter will help draw that signal out and make it more contrasted from the background. You can then even gather some broadband data, which will help retain natural star colors, and blend the two datasets in processing. This is especially true if you shoot a target with multiple nebulae types, take the Trifid for example. That’s a combination of emission, reflection, and dark nebulae — the latter two being best with broadband signal.

As others have mentioned, though, if you rarely shoot from dark skies, you’ll be best off choosing a broadband target, since those aren’t possible from home.

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Die Launische Diva

Jul 3, 2023 · Edited: Jul 3, 2023

You have the opportunity to image from pristine skies. Use that opportunity wisely for benchmarking your equipment and your processing skills at their simplest form (meaning without filters and no convoluted processing). Also, if you have spare imaging time, try imaging something you have imaged before and see if you are getting better results than your light-polluted site. And don't forget to enjoy the starry sky with your unaided eyes, or at least with a pair of binoculars

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Arun H

Frequent contributor

Jul 3, 2023

If I could recommend Die Launische Diva's post a hundred times, I would.

Imaging and observing from a Bortle 2 site is a privilege. I would choose a broad band target and would not dream of using any kind of filter. Filters cut desirable light as well as undesirable light. While necessary from a light polluted site, it is completely counterproductive from a Bortle 1 or 2 site. Even targets rich in emission lines such as the Lagoon and Eagle have considerable broad band emissions from dust and not using a filter will allow you to capture very rich colors. If you should want at some point to add narrow band data, you can always use a filter from your home later on - don't waste precious dark sky time using a narrow band filter, focus on broad band data.

And yes, take the time to visually observe, not just the stars but things like zodiacal light. I was fortunate to see the Milky Way from the top of Haleakala in Maui, and the sight absolutely took my breath away. So few people get to experience the sky the way our ancestors did.

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JohnHen

IOTD Staff

Jul 3, 2023 · Edited: Jul 3, 2023

I agree with what has been said: No filter in a Bortle 2 area on OSC. Anything that is narrowband can be shot from backyard. I use a mono camera and when I travel to a Dark Site I only shoot the L filter (and RGB and Ha etc. from home). This way I make maximum use of the (limited) Dark Site time …
CS, John

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