Tri-band "RGB" filters?

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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!

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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?

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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…

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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 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.

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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…. 🤣