Tri-band "RGB" filters?

Filters
10 replies•242 views
Jeff Russell avatar
Jeff Russell avatar

I’m thinking of buying a tri-band RGB filter, like this one from Antlia: https://shop.antliafilter.com/products/antlia-triband-rgb-ultra-filter-ii-2-mounted

📷 Untitled.jpgUntitled.jpg

Glancing at the spectrum diagram it looks like it blocks around 80% of visible light, with two admitted bands for common emission wavelengths as well as a third “blue” band for reflection nebulae. I’ve been enjoying shooting broadband when I get the chance to visit a dark sky site a few nights a month, but most of the time I’m in the city. My thinking is this filter might be a good use for my OSC camera. I already have a 7nm dual band filter as well.

I’m still in my first year with this hobby, so any thoughts or guidance are welcome. Thanks!

Well Written Respectful
andrea tasselli avatar
andrea tasselli avatar
Not that great if you think of shooting BB. Either no filter (i.e, UV/IR filter) or something with larger pass-bands such as the Optolong L-Pro/L-Quad LP filters.
Jeff Russell avatar
Jeff Russell avatar

General concept with the L-Pro/L-Quad seems to be blocking mercury and sodium lines. That makes some sense, but is this still useful in the era of white LEDs?

Well Written Engaging
Tony Gondola avatar
Tony Gondola avatar

I agree with all of the above. The results I think will be disappointing. It’s letting in a lot of LED broadband light pollution while cutting off the near IR which can be very useful. I don’t know what the B number is for your site but if it’s much above 6, You would be better off using the near Ir for L frames (of your optics can handle it) and a classic dual band filter 7 nm or tighter. No filter or no filter with uv/ir cut would also give useful results, just keep the subs in the right exposure range to swamp read noise but not picking up too much sky background. It’s a dance…

Helpful Respectful Concise Engaging Supportive
alpheratz06 avatar
alpheratz06 avatar

Without consideration for the relative weakness of OSC as regards NB , because you cannot have the bottle full and the lady drunk.

1 if you shoot full NB, some pixels are useless

2 with the tri band filter, you use in theory all the pixels , but you mix Ha and SII as well as OIII and Hbeta

If you already have a dual band (I assume it is HA/OII ) I would consider to complement either with

  • a SII filter or

  • a SII / OIII filter (you get more OIII or

  • a SII/Hb filter if you are curious about HB In most situation Hb and Ha look similar but it might be a way to workaround lens chromaticism if any

I think another dual band would be a good compromise.

SonnyE avatar
SonnyE avatar

I’ve always used individual filters, when I used filters. (A long time ago in a Galaxy far, far away…)

I live in a B7-9 light pollution area (depends on which A’holes have their unnecessary outdoor lights turned on.)

Last year and this year I’ve been trying out an Antlia Quad LP filter, and this year an Svbony SV220 3nm dual band filters. First times for me to try out multi-band filters and I like them so far.

I’m confident you would like the Antlia filters. I would suggest you buy from a vendor that has at least a 30-day satisfaction return policy. That way you could return it if you do not like it.

With my ASI2600MC Pro, and a filter drawer, I can shoot one night with one of these multi-band filters and the next with the other to compare the results. I like the results with both, but the quad is a more rounded color result and the 3nm gives a much redder result due to it being Ha and OIII only.

But if you don’t try the filter you will always wonder if it could have worked for you with your choice of equipment. IE: telescope and camera.

Well Written Helpful
SonnyE avatar
SonnyE avatar

alpheratz06 · Feb 25, 2026, 04:52 PM

Without consideration for the relative weakness of OSC as regards NB , because you cannot have the bottle full and the lady drunk.

You can if you buy two bottles…. 🤣

Stelios_Stergiou avatar
Stelios_Stergiou avatar

Take a look at sv260 multiband it is for max b6, if you are in b6+ sky I think there is a sv240 for this

https://www.astrobin.com/c6x5a7/

ZigZagZebraz avatar
ZigZagZebraz avatar

I have the Antlia triband RGB Ultra ii. It works well for me. But, I am in an SQM 21.5 zone, whatever Bortle it is.

On my profile, except for the first and the third images (Newest to the oldest), rest were shot using that filter.

I have used it from the New moon to the full moon (as long as the moon is 50° or further away from the target.

Helpful Respectful
DarkSkyTim avatar
DarkSkyTim avatar

Jeff Russell · Feb 25, 2026, 04:15 PM

General concept with the L-Pro/L-Quad seems to be blocking mercury and sodium lines. That makes some sense, but is this still useful in the era of white LEDs?

In theory, not much use. The LEDs out there today are broadband and emit light in the same wavelengths of many of the objects you’d be trying to image. The blue LEDs are really an astronomer’s worst nightmare

SonnyE avatar
SonnyE avatar

I was told (wrongly) that my quad LP filter would double the IR blocking because my camera already has an IR filtering in it.

In reality, I’m happy as spiked punch with my quad band LP filter. When you think about it, my Antlia quad LP filter blocks certain wave lengths. So how can it compound the IR blocking if no or little IR gets through?

The only additional IR blocking would be that which is not blocked already by the quad filter. It is illogical to assume the two filters would compound IR filtering.

Convince me I’m wrong….

Something else to consider when considering multi filters is if you wanted to expose longer in one or another color, you can’t. Not that it’s a bad thing, but something to be aware of. I’m really liking my multi-filters for light pollution. Kills the whole flock with one stone (or hand grenade). But that was the hope of going with multi-band.

Well Written Engaging
Related discussions
Capuring RGB for stars at the same time and prosessing it with Mono Cameras.
Hello. Instead of capturing RGB separately for stars, is it possible with this filter: Antlia Triband RGB Ultra Filter 2" to get RGB at the same time. I have ASI 1600 MM Pro.
Directly addresses the same Antlia tri-band RGB filter product and its capabilities.
Jul 13, 2025
To mono, or not to mono... That is the question.
I'm about to purchase the ASI2600MC Pro and I got to thinking, should I go mono now, or wait. I have been at this a year and have been shooting OSC with an ASI294MC Pro and I like the results, but I think I may want to step it up a notch, even th...
Discusses RGB filter options relevant to author's mono camera upgrade decision.
Apr 9, 2024
Extremely noisy RGB
Hi! I have the following problem with my RGB: it's too noisy! I apply NoiseXTerminator, different parameters, and I can't reduce the noise. My RGB is 60 images per channel of 60 seconds. My camera was refrigerated at -10C. I checked if there ...
Tri-band filters may reduce noise in RGB astrophotography data processing.
Mar 22, 2025
Weird semicircle in my images using the Antlia Tri-band filter
Desktop.jpeg Desktop.jpeg two images from my Nikon 810a modified full frame DSLR. Both are shot with the Antlia tri-band filter, the Jellyfish is shot with the Skywatcher 82ed evostar with the reducer/flattener, the other is shot with the Celestron C...
Author uses Antlia tri-band filter; this discusses tri-band filter selection and options.
Feb 9, 2025