I have an 8×31mm EFW and I am trying to decide on a filter to go in the currently empty 8th slot. I have clear, RGB, HSO in there now.
Do I go with an IR pass filter? Or block it off for darks? Or something else?
8th position in FW
Well Written Engaging
Hbeta
Since you are shooting with a Newtonian, I vote Ir pass. You’ll find it very useful for L-frames if have a degree of light pollution.
When I was doing mono shooting, I took an old filter and blacked it out so I could automate gathering darks with Position 8.
I programed Darks and Bias’ with hole 8, in NINA. Worked great.
Nii (3nm) from Chroma.
For Darks and Bias you can use Sii with the end of your scope covered (like with a Deep Sky Dad flat panel)
For Darks and Bias you can use Sii with the end of your scope covered (like with a Deep Sky Dad flat panel)
Since you have a Newtonian I would choose a clear filter. About 20% to 40% more signal for you luminance data depending on the sensor compared to a UV/IR cut.
andrea tasselli · Feb 8, 2026, 09:52 PM
Hbeta
Thanks i have used a H beta filter before and didn’t find it terribly useful.
John Stone · Feb 9, 2026, 11:30 AM
Nii (3nm) from Chroma.
For Darks and Bias you can use Sii with the end of your scope covered (like with a Deep Sky Dad flat panel)
Thanks, a bit rich for my wallet I’m afraid.
Since you have a Newtonian I would choose a clear filter. About 20% to 40% more signal for you luminance data depending on the sensor compared to a UV/IR cut.
Yes I am already using a clear filter for luminance (instead of a UV/IR cut filter). That’s why I’m not sure about the IR pass filter in the 8th slot as I’m already capturing that signal in my luminance subs.
I think I will get an old filter and paint it black to use for darks, seems the most useful way to use the slot.
Argon ii, because it's exotic sounding.
Don't think many targets are strong emitters but who knows ?
Don't think many targets are strong emitters but who knows ?
Craig Towell · Feb 9, 2026, 01:12 PM
andrea tasselli · Feb 8, 2026, 09:52 PM
Hbeta
Thanks i have used a H beta filter before and didn’t find it terribly useful.
John Stone · Feb 9, 2026, 11:30 AM
Nii (3nm) from Chroma.
For Darks and Bias you can use Sii with the end of your scope covered (like with a Deep Sky Dad flat panel)Thanks, a bit rich for my wallet I’m afraid.
Since you have a Newtonian I would choose a clear filter. About 20% to 40% more signal for you luminance data depending on the sensor compared to a UV/IR cut.
Yes I am already using a clear filter for luminance (instead of a UV/IR cut filter). That’s why I’m not sure about the IR pass filter in the 8th slot as I’m already capturing that signal in my luminance subs.
I think I will get an old filter and paint it black to use for darks, seems the most useful way to use the slot.
The Ir pass would only make sense if you have a lot of light pollution or if there are structures in the near Ir you want to bring out.
Craig Towell · Feb 9, 2026, 01:12 PM
I think I will get an old filter and paint it black to use for darks, seems the most useful way to use the slot.
That is what I did Craig.
Mask off the threads well. I used flat black, spray paint. 2 coats.