What does the L-Ultimate do against no filter?

On the Askar 185 with the same camera, the Veil, the Elephant's Trunk and the North America Nebula come out far stronger through it than in my frames without it, both nights under a bright Moon.

The 1.25 inch version. Optolong lists the 2 inch, and First Light Optics sells both sizes.

Can I use it with a fast telescope?

Optolong says it is not suitable for fast focal ratio systems. I used it on the Askar 185 at f/7 and on the Celestron 8" EdgeHD.

Which rigs did I use it on?

The Askar 185APO with the ZWO ASI6200MC Pro on the EM31 Pro, and the Celestron 8" EdgeHD with the ToupTek ATR533C on the Celestron AVX.

L-Ultimate or SVBONY SV220?

Both are 3 nm dual-band filters for colour cameras. The SV220 won my three-way dual-band test and costs less; I have not tested the L-Ultimate side by side with it.

Optolong L-Ultimate review: 3nm dual-band, with and without

Where does it rank on our leaderboard

Nine of the 13 filters on my board, against price
Rank	Filter	Stars for Your Buck	Recorded UK price
1	Scorpio HSO 3nm	100 out of 100	£448
2	Laida HSO 5nm 1.25″	94 out of 100	£154
4	Altair LRGB	79 out of 100	£240
5	Altair HSO 6.5nm/7nm Narrowband	76 out of 100	£475
6	QuarkStar Chromosphere	76 out of 100	£1,149
8	Altair Ha OIII 4nm	74 out of 100	£399
11	Optolong L-Enhance	61 out of 100	£149
12	Optolong L-Ultimate Dual-Bandpass 3nm	43 out of 100	£216
13	ZWO HSO 7nm Narrowband	32 out of 100	£734

Contents

01 Where does it rank on our leaderboard
02 Specifications and features
03 The same target through each filter
04 How good is it? Here's what I captured
05 Raw against finished
06 In my words
07 Watch it in my videos
08 Should you buy it?
09 Questions and more about this review

In 30 seconds

Stars for Your Buck 43/100

Reviewed 24 Jul 2025 Updated 25 Sep 2026

Rank: #12 of 13 filters
Verdict: With reservations

Written by Damon Scotting 5 min read

Buy it if

You image emission nebulae with a one-shot colour camera from a light-polluted sky.
You want to keep imaging nebulae when the Moon is bright.
You guide your mount and can run long exposures.

Skip it if

You image through a very fast astrograph.
You want the best-value 3 nm dual-band filter.
You mostly image galaxies and star clusters.

“You can really tell in this shot of the Ring Nebula that you're getting your money's worth with the filter.”

Specifications and features

Against the filters I have reviewed

Compare with

Optolong L-Ultimate Dual-Bandpass 3nm reviewed #12 of 13	SVBONY SV220 Ha OIII 3nm #3 of 13	Altair Ha OIII 4nm #8 of 13	Optolong L-Enhance #11 of 13
Recorded UK price	£216	£249	£399	£149
Stars for Your Buck	43/100	92/100	74/100	61/100
Type	Dual-band narrowband filter (H-alpha and OIII)	Dual-band narrowband filter (H-alpha and OIII)	Dual-band: Ha and OIII in one filter	Dual-bandpass light pollution filter (H-alpha, H-beta and OIII)
Bandpass	3 nm OIII, 3 nm H-alpha	3 nm OIII, 3 nm H-alpha, tolerance ±1	4 nm each band, tolerance about ±0.5	H-alpha 10 nm; OIII + H-beta 24 nm
Lines passed	OIII 500.7 nm, H-alpha 656.3 nm	OIII 500.7 nm, H-alpha 656.3 nm	OIII 500.7 nm and Ha 656.3 nm	H-alpha, H-beta, OIII
Peak transmission	90% or more on average	85% or more on average (OIII and H-alpha)	Ha 90 to 94%, OIII 88 to 91%	Over 90%
Sizes	1.25 inch (the size I use), 2 inch	2 inch, M48 x 0.75 (the size I used); 1.25 inch also sold	2 inch (M48 x 0.75 thread)	1.25 inch, 2 inch (the size I tested), Canon EOS-C clip-in
Thickness	1.85 mm	2.0 mm substrate	1.85 mm	1.85 mm B270 glass
Coating	Multi-layer anti-reflection, non-cemented, ion-assisted deposition	Multi-layer minimal halo coating	SiO2 hard overcoat with UV/IR block and anti-reflection coating	Multi-layer anti-reflection, non-cemented, ion-assisted deposition
In the box	Protective plastic case with EVA foam lining	2 inch SV220 3 nm filter; plastic case; outer packing box	Filter and its spectrographic test report	Protective plastic case with EVA foam lining

The same target through each filter

The Optolong L-Ultimate Dual-Bandpass 3nm against the No filter on Veil Nebula, Elephant's Trunk and North America Nebula, one telescope and one camera, star-aligned

Against

⇔

No filter Optolong L-Ultimate Dual-Bandpass 3nm Veil Nebula drag

Veil Nebula (supernova remnant) · Askar 185APO, ZWO ASI6200MC Pro, EM31 Pro · Bortle 6.8 (in my garden) Left: No filter, 30 min (6 x 300 s) Right: Optolong L-Ultimate Dual-Bandpass 3nm, 30 min (6 x 300 s)

Veil Nebula: Askar 185APO, ZWO ASI6200MC Pro, EM31 Pro, Bortle 6.8 (in my garden); Optolong L-Ultimate Dual-Bandpass 3nm 30 min (6 x 300 s); No filter 30 min (6 x 300 s)
Elephant's Trunk: Askar 185APO, ZWO ASI6200MC Pro, EM31 Pro, Bortle 6.8 (in my garden); Optolong L-Ultimate Dual-Bandpass 3nm 30 min (6 x 300 s); No filter 30 min (6 x 300 s)
North America Nebula: Askar 185APO, ZWO ASI6200MC Pro, EM31 Pro, Bortle 6.8 (in my garden); Optolong L-Ultimate Dual-Bandpass 3nm 30 min (6 x 300 s); No filter 30 min (6 x 300 s)

How good is it? Here's what I captured

Six targets

NGC 6960 Veil Nebula, ASI6200MC Pro, Optolong L-Ultimate

Integration: 30 min (6 x 300 s)
Field: 1.59 x 1.06 degrees
Telescope: Askar 185APO
Camera: ZWO ASI6200MC Pro
Mount: EM31 Pro
Target: NGC 6960 Veil Nebula
Type: Supernova remnant
Location: Bortle 6.8 (in my garden)

NGC 7000 North America Nebula, ASI6200MC Pro, Optolong L-Ultimate

Integration: 30 min (6 x 300 s)
Field: 1.59 x 1.06 degrees
Telescope: Askar 185APO
Camera: ZWO ASI6200MC Pro
Mount: EM31 Pro
Target: NGC 7000 North America Nebula
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

IC 1396 Elephant's Trunk Nebula, ASI6200MC Pro, Optolong L-Ultimate

Integration: 30 min (6 x 300 s)
Field: 1.59 x 1.06 degrees
Telescope: Askar 185APO
Camera: ZWO ASI6200MC Pro
Mount: EM31 Pro
Target: IC 1396 Elephant's Trunk Nebula
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

NGC 2359 Thor's Helmet, ToupTek ATR533C, Optolong L-Ultimate

Integration: 3 h 36 min (72 x 180 s)
Field: Unknown
Telescope: Celestron 8" EdgeHD
Camera: ToupTek ATR533C
Mount: Celestron AVX
Target: NGC 2359 Thor's Helmet
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

NGC 6888 Crescent Nebula, ToupTek ATR533C, Optolong L-Ultimate

Integration: 30 min (10 x 180 s)
Field: Unknown
Telescope: Celestron 8" EdgeHD
Camera: ToupTek ATR533C
Mount: Celestron AVX
Target: NGC 6888 Crescent Nebula
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

M 57 Ring Nebula, ToupTek ATR533C, Optolong L-Ultimate

Integration: 1 h (20 x 180 s)
Field: Unknown
Telescope: Celestron 8" EdgeHD
Camera: ToupTek ATR533C
Mount: Celestron AVX
Target: M 57 Ring Nebula
Type: Planetary nebula
Location: Bortle 6.8 (in my garden)

Raw against finished

In my words

The 3 targets, the raw combined stack against my finished image, each with its integration, the camera and the palette:

NGC 6960 Veil Nebula: 30 min (6 x 300 s) of light, ASI6200MC Pro, Optolong L-Ultimate, the raw combined stack with one automatic stretch
NGC 7000 North America Nebula: 30 min (6 x 300 s) of light, ASI6200MC Pro, Optolong L-Ultimate, the raw combined stack with one automatic stretch
IC 1396 Elephant's Trunk Nebula: 30 min (6 x 300 s) of light, ASI6200MC Pro, Optolong L-Ultimate, the raw combined stack with one automatic stretch

“There's almost a second layer of surrounding nebulosity that standard setups can't really pick up.”

From my C8 EdgeHD video, on M 57 through the L-Ultimate

“When using this filter our images are going to be a lot fainter.”

From my C8 EdgeHD video

Watch it in my videos

Is BIGGER always BETTER? (Askar 103 v 140 v 185 Telescope) · published 24 July 2025 · 10:21 · Watch on YouTube · 55,018 views, 1,493 likes on 2 Oct 2026

Jump to

4:14 The L-Ultimate at the back of the Askar 185
4:28 Why it matters on a full-Moon night
4:56 Veil Nebula without and with the filter
5:11 Elephant's Trunk without and with the filter
5:21 North America Nebula without and with the filter

Transcript of the video 180 words · 2 chapters · searchable

Press a time stamp to play from there.

4:05 The opening

4:05 So because of this telescope, we are very much putting this to a stress test. 4:05 But I am quite confident that it's gonna be more than capable of doing so. 4:09 In fact I'm so confident that as you can see I've attached a bunch of different accessories.

4:14 The L-Ultimate at the back of the Askar 185

4:14 Just at the very back here I have an Optolong L-Ultimate filter where using this filter is supposedly going to cut through a large chunk of it and allow me to image the night sky, and that is doubly important tonight because tonight is a full moon, which, as far as deep-sky imaging goes, is pretty much the worst time ever to image the night sky. Yeah, I'm not going to say it's pointless, but compared to the images that you achieve under moonless skies they just look rubbish. The goal that I'm hoping to achieve tonight is I want to image the same objects with the filter attached. So, without further ado, we've seen the Askar 103, we've seen the Askar 140, now let's see what the Askar 185 can really do.

Check out more videos on the Optolong L-Ultimate Dual-Bandpass 3nm

What YOU can SEE with a £2000 "USED" Telescope setup?!

12 Jul 2025

Should you buy it?

43/100 Stars for Your Buck

Pros

Against the same three targets without it, it brought out far more nebulosity on my Askar 185.
3 nm on each line: the narrowest bandpass of the dual-band filters I have tested, level with the SVBONY SV220.
Through a Celestron 8" EdgeHD it captured Thor's Helmet, the Crescent Nebula and the Ring Nebula.
It comes in 1.25 inch as well as 2 inch.

Cons

It cuts so much light that I added a guide scope and guide camera to run longer exposures.
Optolong says it is not suitable for fast focal ratio systems.
It costs more than the SVBONY SV220: Optolong's list price for the 2 inch is $389, and SVBONY sells the 2 inch SV220 for $280.
Optolong publishes no peak transmission figure for it.

Using intense filters like this really limits the amount of total light coming through, so longer exposures are a must.

Who the L-Ultimate is for

Colour camera in a light-polluted sky

Buy

Against the same targets with no filter it brought out far more nebula with the same camera and telescope.

Imaging under a bright Moon

Buy

I used it on a full-Moon night and still captured the Veil, the Elephant's Trunk and the North America Nebula.

Fast astrograph owner

Skip

Optolong does not recommend it for fast focal ratio systems.

Value hunter

Skip

The SVBONY SV220 is a 3 nm dual-band filter too, and size for size it costs less.

Unguided tracker user

Skip

It passes so little light that it wants long, guided exposures.

Mono camera owner

Skip

Separate narrowband filters give a mono camera each channel on its own.

Three alternatives I have reviewed

Questions and more about this review

Reviewed by

Damon Scotting

The Telescope Man Verified

BSc (Hons) Physics with Astrophysics and Cosmology, Loughborough University PGCE / QTS, University of Nottingham

About Damon About Damon Damon Scotting is The Telescope Man. He holds a BSc (Hons) in Physics with Astrophysics and Cosmology from Loughborough University and a PGCE with QTS from the University of Nottingham, and taught physics in secondary schools before becoming an astronomy creator. He is a contributing writer for BBC Sky at Night Magazine and the author of 42 Wonders of Our Night Sky, and his photograph of the galaxy M100 with the dwarf planet Ceres was Highly Commended in the Astronomy Photographer of the Year 2024 competition run by Royal Observatory Greenwich. He has appeared on the BBC's Blue Peter. More than 750,000 people follow his astronomy channels on YouTube, Instagram and TikTok, and he has reviewed more than 140 telescopes, mounts, cameras, filters and accessories hands-on for this site. More about Damon · How I test · Damon's book

I review all kinds of gear: most of it I buy, some is gifted and some is loaned, and all of it is reviewed the same way. How this site is funded

Five questions, answered

Questions about the Optolong L-Ultimate Dual-Bandpass 3nm

Reviewed 24 July 2025 ·Updated 25 September 2026

I review all kinds of gear. Most of it I buy, some is gifted and some is loaned, and all of it is reviewed the same way: no company sees or approves a review before it is published. Shop links marked Ad are affiliate links: I earn a commission when you buy through them, at no extra cost to you. How this site is funded

What does the L-Ultimate do against no filter? On the Askar 185 with the same camera, the Veil, the Elephant's Trunk and the North America Nebula come out far stronger through it than in my frames without it, both nights under a bright Moon. The same target through each filter ↓
Which size do I use? The 1.25 inch version. Optolong lists the 2 inch, and First Light Optics sells both sizes. The specifications and the comparison table ↓
Can I use it with a fast telescope? Optolong says it is not suitable for fast focal ratio systems. I used it on the Askar 185 at f/7 and on the Celestron 8" EdgeHD. The specifications and the comparison table ↓
Which rigs did I use it on? The Askar 185APO with the ZWO ASI6200MC Pro on the EM31 Pro, and the Celestron 8" EdgeHD with the ToupTek ATR533C on the Celestron AVX. What I captured ↓
L-Ultimate or SVBONY SV220? Both are 3 nm dual-band filters for colour cameras. The SV220 won my three-way dual-band test and costs less; I have not tested the L-Ultimate side by side with it. The specifications and the comparison table ↓