Are the Antlia 2.5nm filters worth the money?

They gave the best Ha frames in my five-set comparison, but the Scorpio 3 nm set came very close for a fraction of the price. If light pollution is your main problem and budget is not, yes.

Antlia 2.5nm or Scorpio 3nm?

On the same telescope, camera and night their Ha frames were neck and neck. I scored the Antlia 10 and the Scorpio 9 out of 10 for image quality, and the Scorpio won on value.

What focal ratio do the Antlia 2.5nm Ultra filters need?

Antlia recommends f/3.5 or slower. My images were taken at about f/4.8 on the Askar SQA106 and SQA130 and about f/7 on the ZWO FF110.

What comes in the box?

The three filters, each with its own measured transmission and blocking data, according to Antlia.

Where can I buy the Antlia 2.5nm set?

FLO in the UK sells the 2 inch filters one at a time; Agena Astro in the US and Antlia's own store sell the set of three.

What have you imaged with it?

The Veil, Elephant's Trunk, North America and Rosette nebulae on the Askar SQA130 with the ZWO ASI6200MM Pro, and the Heart Nebula on the ZWO FF110, all from my garden.

What have I not tested on the Antlia set?

I have not measured the transmission or bandpass, and my side-by-side test compares the Ha filters only.

Antlia 2.5nm HSO review: the premium narrowband set, tested

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
7	Antlia 2.5nm HSO	75 out of 100	£1,740
8	Altair Ha OIII 4nm	74 out of 100	£399
9	Altair Solar Contrast Booster Filter	73 out of 100	£80
10	ZWO LRGB	70 out of 100	£332
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 In use
05 How good is it? Here's what I captured
06 Raw against finished
07 What is it for
08 In my words
09 Watch the review
10 Should you buy it?
11 Questions and more about this review

In 30 seconds

Stars for Your Buck 75/100

Reviewed 18 May 2026 Updated 25 Sep 2026

Rank: #7 of 13 filters
Verdict: Damon recommends

Written by Damon Scotting 7 min read

Buy it if

You want the narrowest filters I have tested and price is not the deciding factor.
You image from a heavily light-polluted garden or under a bright Moon.
You use a 2 inch filter wheel and optics at f/3.5 or slower.

Skip it if

You want the best value: the Scorpio 3 nm set came very close in my test for far less.
Your optics are faster than f/3.5, outside the maker's recommended range.
You need 1.25 inch filters: this set comes 2 inch mounted or 36 mm unmounted.

“If you want the suffocating light pollution in your area to be an afterthought, then these filters are an excellent choice.”

Specifications and features

Against the filters I have reviewed

Compare with

Antlia 2.5nm HSO reviewed #7 of 13	Scorpio HSO 3nm #1 of 13	Laida HSO 5nm 1.25″ #2 of 13	Altair HSO 6.5nm/7nm Narrowband #5 of 13	ZWO HSO 7nm Narrowband #13 of 13
Recorded UK price	£1,740	£448	£154	£475	£734
Stars for Your Buck	75/100	100/100	94/100	76/100	32/100
Type	Narrowband imaging filters, a set of three (Ultra series)	Narrowband imaging filters, a set of three	Narrowband imaging filters, a set of three	Narrowband set: SII, Ha and OIII filters	Narrowband set: Ha, SII and OIII filters
Bandpass	2.5 nm FWHM (+0.3/-0.1 nm)	3 nm	5 nm FWHM	Ha 7 nm; SII and OIII 6.5 nm	7 nm each, tolerance ±0.5
Lines passed	Ha 656.3 nm, SII 671.6 and 673.1 nm, OIII 500.7 nm	Ha, SII, OIII	Ha, SII, OIII	Ha, SII and OIII	Ha 656 nm, SII 672 nm, OIII 500 nm
Peak transmission	95% or more (Ha, SII); 92% or more (OIII)	not recorded	not recorded	not recorded	About 90% at each line
Sizes	2 inch mounted, M48 x 0.75 (mine); 36 mm unmounted also sold	2 inch mounted, D50 (mine); a 36 mm set is also listed	1.25 inch (mine, model DA1100); a 2 inch set is also listed	2 inch	1.25 inch, 2 inch, 31 mm and 36 mm
Thickness	2 mm (+/- 0.05 mm)	not recorded	not recorded	1 mm BK7 glass	2.0 mm (1.25 inch, 31 mm and 36 mm)
Coating	Quartz glass coated to the edge; OD5 out-of-band blocking	not recorded	not recorded	UV/IR blocking and anti-reflection coatings	IR cut from 700 to 1,100 nm; off-band OD3
In the box	Ha, SII and OIII filters, each with its measured transmission and blocking data	Ha, SII and OIII filters, each in its own case	Ha, SII and OIII filters, each in its own box	SII, Ha and OIII filters, each in a sealed case	Ha, SII and OIII filters

The same target through each filter

The Antlia 2.5nm HSO against four other filters on North America, Sadr and Owl, one telescope and one camera, star-aligned

Against

⇔

Laida HSO 5nm 1.25″ Antlia 2.5nm HSO North America drag

North America (emission nebula) · Askar SQA106, ZWO ASI2600MM Pro, ZWO AM3N · Ha only · Bortle 6.8 (in my garden) Left: Laida HSO 5nm 1.25″, 15 min (5 x 180 s) Right: Antlia 2.5nm HSO, 15 min (5 x 180 s)

On the Laida HSO 5nm 1.25″

“Star haloing. And perhaps even more worrying is that the haloing is off-centred.”

From my filter comparison video

On the Antlia 2.5nm HSO

“How does the Antlia filter compare versus the Laida? It destroys it. What about the ZWO? It annihilates it. And the Altair? It's just all too easy. But as for the Scorpio filter set, that generally seems to be neck and neck to me.”

From my filter comparison video

Read my review of the Laida HSO 5nm 1.25″

North America: Askar SQA106, ZWO ASI2600MM Pro, ZWO AM3N, Bortle 6.8 (in my garden); Antlia 2.5nm HSO 15 min (5 x 180 s); Scorpio HSO 3nm 15 min (5 x 180 s); Laida HSO 5nm 1.25″ 15 min (5 x 180 s); ZWO HSO 7nm Narrowband 15 min (5 x 180 s); Altair HSO 6.5nm/7nm Narrowband 15 min (5 x 180 s)
Sadr: Askar SQA106, ZWO ASI2600MM Pro, ZWO AM3N, Bortle 6.8 (in my garden); Antlia 2.5nm HSO 15 min (5 x 180 s); Scorpio HSO 3nm 15 min (5 x 180 s); Laida HSO 5nm 1.25″ 15 min (5 x 180 s); ZWO HSO 7nm Narrowband 15 min (5 x 180 s); Altair HSO 6.5nm/7nm Narrowband 15 min (5 x 180 s)
Owl: Askar SQA106, ZWO ASI2600MM Pro, ZWO AM3N, Bortle 6.8 (in my garden); Antlia 2.5nm HSO 15 min (5 x 180 s); Scorpio HSO 3nm 15 min (5 x 180 s); Laida HSO 5nm 1.25″ 15 min (5 x 180 s); Altair HSO 6.5nm/7nm Narrowband 15 min (5 x 180 s)

In use

Ha, SII and OIII, 2 inch mounted

The three filters side by side

Stacked, gold rims and labels

Beside the Scorpio 3 nm set

In my 2 inch filter wheel

The five sets I compared

How good is it? Here's what I captured

Five targets

Veil Nebula, ASI6200MM Pro, Antlia 2.5 nm

Integration: 3 h
Field: 2.9 x 1.9 degrees
Telescope: Askar SQA130
Camera: ZWO ASI6200MM Pro
Mount: ZWO AM7
Target: Veil Nebula (NGC 6960 and NGC 6992)
Type: Supernova remnant
Location: Bortle 6.8 (in my garden)

Elephant's Trunk, ASI6200MM Pro, Antlia 2.5 nm

Integration: 12 h
Field: 3.3 x 2.2 degrees
Telescope: Askar SQA130
Camera: ZWO ASI6200MM Pro
Mount: ZWO AM7
Target: Elephant's Trunk Nebula (IC 1396)
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

NGC 7000, ASI6200MM Pro, Antlia 2.5 nm

Integration: 3 h
Field: 3.3 x 2.2 degrees
Telescope: Askar SQA130
Camera: ZWO ASI6200MM Pro
Mount: ZWO AM7
Target: North America Nebula (NGC 7000)
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

Rosette, ASI6200MM Pro, Antlia 2.5 nm

Integration: 36 min (12 x 180 s)
Field: 3.3 x 2.2 degrees
Telescope: Askar SQA130
Camera: ZWO ASI6200MM Pro
Mount: ZWO AM7
Target: Rosette Nebula (NGC 2237)
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

Heart Nebula, ASI6200MM Pro, Antlia 2.5 nm

Integration: 1 h 15 min (25 x 180 s)
Field: 2.7 x 1.8 degrees
Telescope: ZWO FF110
Camera: ZWO ASI6200MM Pro
Mount: ZWO AM3N
Target: IC 1805 Heart Nebula
Type: Emission nebula
Location: Bortle 6.8 (in my garden)

Raw against finished

What is it for

The 4 targets, the raw combined stack against my finished image, each with its integration, the camera and the palette:

Elephant's Trunk Nebula (IC 1396): 12 h of light, ASI6200MM Pro, Antlia 2.5 nm Ha, SII, OIII, the raw combined stack with one automatic stretch
North America Nebula (NGC 7000): 3 h of light, ASI6200MM Pro, Antlia 2.5 nm Ha, SII, OIII, the raw combined stack with one automatic stretch
Rosette Nebula (NGC 2237): 36 min (12 x 180 s) of light, ASI6200MM Pro, Antlia 2.5 nm Ha, SII, OIII, the raw combined stack with one automatic stretch
IC 1805 Heart Nebula: 1 h 15 min (25 x 180 s) of light, ASI6200MM Pro, Antlia 2.5 nm Ha, SII, OIII, the raw combined stack with one automatic stretch

Three things it is for

Narrowband under a full Moon

Narrowband imaging works exceptionally well during a full moon because it captures only very specific wavelengths like hydrogen alpha, sulphur II and oxygen III, blocking most of the broadband moonlight and sky glow that would otherwise wash out the image.

Cutting through light pollution

Theoretically speaking, these filters will isolate the wavelengths of light that reach the camera sensor so well that my Bortle should effectively drop from a hazy 6.8 to a mesmerizing 2.

Vivid colour from a bright garden

The goal was to cut through the dense light pollution in my area to give me some stunning vibrant displays.

In my words

“The Antlia filters do look the most premium by far. This golden design and detailed labeling makes them feel so much more premium.”

From my video review

“And without the ability to compare them versus other filters directly under the same imaging conditions with precisely the same gear, I think I would have unanimously decided that the Antlia filters were in fact the best.”

From my video review

“This is the 62-megapixel ASI 6200, partnered with the top-of-the-range Antlia 2.5nm narrowband filters.”

From my Askar SQA130 video review

Watch the review

£58 vs £1369 Filters, Can You Tell the Difference? · published 18 May 2026 · 16:23 · Watch on YouTube · 14,152 views, 497 likes on 2 Oct 2026

Jump to

2:32 Antlia 2.5nm, the premium tier
2:55 The test rig, SQA106 + 2600MM + 2 inch wheel
6:33 Antlia 2.5nm, the champion?
7:11 Antlia vs Scorpio, neck and neck
7:35 Switching to Sadr star
11:35 Final ranked results table
13:57 Second place, Antlia

Transcript of the review video 2,918 words · 25 chapters · searchable

Press a time stamp to play from there.

0:00 The £19 vs £434 filter question

0:00 Presenting the ultimate filter comparison video. 0:03 Tonight we're going to compare the images captured through a very mixed bag of filters, including a 19 pound 5 nanometre off-brand filter versus a 434 pound 2.5 nanometre Antlia filter. 0:16 I say this not with the intention to clickbait, but the results here will really surprise you. 0:20 So let's see which filter will come out on top.

0:22 Intro

0:22 I'm Damon Scotting and this is Astronomical.

0:25 Tonight's sky, full moon Bortle 9

0:27 It is a gorgeous night here in the middle of England. 0:30 It is a full moon, which means the Bortle has jumped from a pleasant 6.8 to a 9. 0:35 It's the kind of night where imaging in broadband can be virtually impossible. 0:39 The powerful, reflected light from the moon washes away most deep sky objects. 0:43 But there is a secret to success when it comes to astrophotography during a full moon, and that involves using narrowband filters. 0:50 Narrowband imaging works exceptionally well during a full moon because it captures only very specific wavelengths like hydrogen alpha, sulfur 2 and oxygen 3, blocking most of the broadband moonlight and sky glow that would otherwise wash out the image.

0:51 Why narrowband works during a full moon

1:03 So it might not look like it, but tonight is the perfect night to test out the hydrogen alpha filters for all five of these filter companies. 1:11 So, without further ado, let's meet today's competition. 1:14 On the extreme budget side of things today, we have the Laida filter set.

1:14 Meet the contestants, Laida £58

1:18 These cost a whopping 58 British pounds, and they are unlike anything else in the field. 1:23 Astrophotography is many things, but affordable isn't one of them. 1:26 So treat these like the holy grail. 1:28 Most popular affordable filter sets tend to be around the 7 nanometre range in terms of their bandwidth. 1:33 But this filter set claims an impressive 5 nanometres. 1:36 Hmm, this really does seem like a definition of too good to be true. 1:40 To the right of them, we have the first narrowband filters I ever owned.

1:43 Altair 7nm £475

1:43 These are the Altair HSO filter set, coming in at a respectable cost of £475 for the 2 inch set. 1:51 That might seem like a significant jump considering we just explored a £58 set, but I promise you, these 2 inch filters are the most affordable, industry-leading filters on the market. 2:01 Speaking of which, next up we have perhaps the most popular narrowband set on the market.

2:04 ZWO 7nm £734

2:05 The ZWO filters retail for £734 here in the UK, and have very similar specifications to the Altair set. 2:12 We can almost treat these filters as our general benchmark. 2:15 Then we have another off-brand set, which promises some big results at some frankly shocking prices.

2:21 Scorpio 3nm £379

2:21 They sell on AliExpress for less than £379, and at 3 nanometres, they are almost the most powerful filters in this video. 2:29 I say almost, because leading the charge, we have the epitome of no expense spared astrophotography gear.

2:32 Antlia 2.5nm, the premium tier

2:34 These are the Antlia 2.5 nanometre HSO filters, and it really doesn't get much better than this. 2:40 As a set, they cost more than most entire astrophotography rigs, which is crazy to say. 2:46 But if they promise us almost three times the results of filter sets half their price, then I think we can agree that they are a bargain. 2:53 Now in order to make this a fair test, I'm actually going to be taking the Hydrogen Alpha filters from each of the sets, and placing them into my 2 inch filter wheel.

2:55 The test rig, SQA106 + 2600MM + 2 inch wheel

3:00 I'll be using the incredibly sharp Askar SQA106 telescope as our imaging scope, and the rather large ASI 2600 monochrome as our imaging camera. 3:08 So this is a very powerful setup. 3:10 But perhaps the first thing you will note is that the bargain bin Laida filter set is at a disadvantage, since it's only 1.25 inches. 3:17 Now there are 2 inch versions of this filter available out there that would have been better suited for this test, but as you will shortly see, the Laida 1.25 inch filters still manage just fine. 3:27 Which is really weird, so I've made another video on this that I'll be posting in the near future. 3:31 Okay, let's start imaging so that we can determine once and for all, what is the best value filter set in the world.

3:36 North America Nebula reference image

3:36 So here is a normal colour photo of the North America Nebula. 3:40 This is an hour's worth of stacked images. 3:43 Now here are 15 minute stacked images of the same deep sky object imaged with their Hydrogen Alpha filters. 3:49 Obviously we need the full set of filter images to give ourselves a full colour picture, like this one here, that I captured of the North America Nebula with the Laida 1.25 inch filters the other night. 3:58 But to capture full colour images with each of these filter sets in the same night is basically impossible for me to do, and I don't want there to be any variance in these tests. 4:06 I ideally want to be conducting them under the same conditions, so I'm going to stick to just Hydrogen Alpha images. 4:11 And straight away, boom, kiss of death when it comes to filters.

4:14 Laida Ha first impressions, star halos

4:15 Star haloing. 4:16 And perhaps even more worrying is that the haloing is off-centred. 4:20 Now this will of course be a result of the smaller filter than sensor size, so it's not worth looking too much into this, other than, hey, that's actually a surprisingly decent image from a 19 pound filter. 4:31 You can of course see some slight vignetting in the corners, but if you focus on the central part of the image, it is nice and sharp. 4:37 And now as a means of comparison, here is the Altair 7 nanometre filter, which is a clear and obvious upgrade on the corners. 4:44 But I tell you what, if you crop in a bit, that's a surprisingly small improvement, isn't it? 4:49 I was expecting night and day between these filters, but this has really shocked me.

4:50 Altair vs Laida side by side

4:53 And as for the ZWO 2 inch Hydrogen Alpha filter, I don't know. 4:56 I think that it just got a little worse than the Altair filter. 5:00 What do you think? 5:01 Let me keep switching quickly between the two here. 5:04 Like I said, these two filters have very similar specs, but very different prices, with the ZWO filter price significantly more. 5:11 Let's now do a comparison with the Laida 1.25 inch filter involved as well. 5:15 But now, put the ZWO filter in the middle. 5:18 Yeah, how about that? 5:19 What do you think? 5:20 Who is the winner out of these three filters? 5:22 It is a tricky one, isn't it?

5:23 ZWO joins the fight

5:23 It'd be interesting to get an astrophotographer to blind rank all of these images to determine which one they think is the best. 5:30 They have all been stacked in the same way for the record. 5:32 They were then star aligned to make these comparisons easier on the eye. 5:36 But now, here's where things really start to get interesting. 5:39 We've seen some unique results from our budget-friendly Laida filters, but how is the Scorpio 3 nanometre filter set going to fare?

5:42 Scorpio 3nm, the surprise

5:46 It is cheaper than both of the Altair and ZWO sets, and advertises 3 nanometres compared to their 7, making it, on paper at least, a lot more powerful. 5:56 And based on these images, yeah, I'd back that statement. 5:59 Look how much more the nebulosity stands out in its image. 6:02 The stars are smaller and still nice and round, but it almost looks like we're comparing a single 3 minute long exposure versus 2 hours. 6:09 It is a drastic improvement upon the ZWO filter. 6:13 And by far the most impressive quality is that unlike its cheap 5 nanometre cousin, it does not produce any star haloing, which is a huge win. 6:21 That is a huge positive for the Scorpio filter set. 6:24 Almost half the price of the ZWO set, and yet somehow more than twice as good. 6:28 But is it enough to take down the top tier filter on the market? 6:32 2.5 nanometres is absurdly fine.

6:33 Antlia 2.5nm, the champion?

6:35 You can basically forget about any concerns you have about light pollution when using these filters. 6:40 They're going to make your Bortle 9 garden feel like it's a Bortle 3. 6:44 Oof, what are we thinking here? 6:46 I think we might have to take a deeper look in order to see how this compares versus the Scorpio set. 6:51 Which do you prefer out of the two? 6:53 Because personally, I'm not sure. 6:55 I really am on the fence here. 6:57 I think we're kind of only seeing half the picture here, because without a final colour image, there's still a few factors we can't quite consider. 7:03 But this right here is supposed to be black and white. 7:05 It should be clear who the winner is. 7:08 And yet I'm seeing very little variance between these two filter sets.

7:11 Antlia vs Scorpio, neck and neck

7:11 So let's try something else. 7:12 How does the Antlia filter compare versus the Laida? 7:15 It destroys it. 7:16 What about the ZWO? 7:18 It annihilates it. 7:19 And the Altair? 7:20 It's just all too easy. 7:21 But as for the Scorpio filter set, that generally seems to be neck and neck to me. 7:26 The only way to know for certain who the real winner is, is to point my telescope at another target. 7:30 So let's go for a bright star surrounded by thick dust and gas. 7:34 Now my telescope is pointing at the star Sadr.

7:35 Switching to Sadr star

7:36 But here's the catch that I'm going to elaborate on in another video. 7:40 You see those corners, but you can actually mostly fix them with a few flats taken. 7:44 It completely smooths out the image. 7:46 And as a sneak peek for the future video that I'm going to be releasing using these filters with the same setup, here are some shots that I captured. 7:52 Each target was between 45 to 90 minutes worth of stacked images. 7:56 If you're not already, make sure you're subscribed to see that video in the near future. 8:00 So you can actually polish this turd to look relatively impressive. 8:04 The one aspect you can't naturally fix though, is the star haloing, which is loud and obvious in this image.

8:04 Fixing halos with StarXTerminator

8:10 But to tell you the truth, when editing the images I captured with it in my next video, I used a StarXTerminator tool to split the nebula and stars. 8:19 I then just blended the star halo out of the image, and you couldn't even tell it was there to begin with. 8:23 Does this extra little bit of work required validate the obscenely low price of this filter set? 8:29 Because as we can see, when compared with the Altair 7 nanometre filters, there isn't exactly a stark difference between them. 8:35 Well, maybe it is a bit more noticeable when you zoom in 500%. 8:39 The Laida filter images do seem a tad noisier. 8:42 When it comes to comparing the 7 nanometre hydrogen alpha filters of the Altair and ZWO sets, I dare say that the Altair filter just edges it here. 8:51 I think again, it's probably too close to say, maybe if we zoom in again 500%, it will make it a little bit easier. 8:56 Yeah, so I think the ZWO stars are a tad smaller, which is nicer. 9:00 The filter clearly keeps them tight. 9:02 But as for the nebulosity and level of noise, yeah, now I'm not sure. 9:06 Maybe ZWO gets it. 9:07 Let's just call it a tie between them on this one. 9:10 The Scorpio filter has even smaller and tighter stars while still making the nebulosity feel abundant. 9:16 That is a clear and obvious improvement over both of the 7 nanometre filters. 9:20 I really do like this shot a lot. 9:22 Which then only leaves us with the 2.5 nanometre Antlia hydrogen alpha filter. 9:27 And look at that. 9:28 We've got a very similar scenario here to the two 7 nanometre filters, where it's practically neck and neck with the Scorpio filters. 9:34 There are very little variations between these two images. 9:38 But I don't know if it is because the Antlia is next in line for the comparison, so it feels like naturally it should progress and be better. 9:44 But my heart is leaning towards the Antlia image being the best here out of the bunch. 9:49 Let me do a few sudden switches between the two filters without their names being shown. 9:53 So the point we are now at is do you honestly think that one of these filters is significantly better than the other? 9:59 The entire Scorpio 2-inch 3 nanometre filter set costs less than a single Antlia filter. 10:04 I'm basing this off their prices on AliExpress, by the way. 10:07 If you try to buy the Antlia filters from a local UK retailer, then they become even more expensive. 10:13 I know it actually means very little since it does not affect the performance in the slightest, but the Antlia filters do look the most premium by far. 10:20 This golden design and detailed labeling makes them feel so much more premium. 10:25 And without the ability to compare them versus other filters directly under the same imaging conditions with precisely the same gear, I think I would have unanimously decided that the Antlia filters were in fact the best. 10:36 Yeah, I think the best way to answer which filter produces the best results would be to ask users to blind rank them. 10:42 So if you have an astrophotographer friend or just a friend actually, anyone will do, give them no previous context and ask them to pick their favourite image from the bunch. 10:51 To make it harder to obviously discern them all, I've cropped it by 25%, change the order in which they appear, and flipped all of them. 10:57 So feel free to try and blind rank them for yourself. 11:24 So how did you do? 11:26 Which filter came out on top? 11:27 These are the correct names of each filter and here they are sorted by the price for each full set. 11:32 Personally, when it comes down to price and the quality of image produced by each filter, this is how I have ranked them.

11:35 Final ranked results table

11:37 In terms of price, I think it's fair to say that the Antlia filters are by far the worst, costing well over a thousand pounds. 11:43 And yet, given how much everything costs in astrophotography, I wouldn't say the prices are extortionate. 11:48 They are probably exactly what you should be expecting to pay for two and a half nanometre filters. 11:53 Especially when one of the biggest brands in the world still sells their seven nanometre filters for a little under one thousand pounds. 11:59 The Altair filters provided very different results. 12:02 They list very similar specs and cost a lot less than ZWO. 12:05 But overall, they actually only cost a little bit more than the three nanometre Scorpio filters I found on AliExpress. 12:12 I would say that these are without a doubt the greatest value filters in the world if it wasn't for the fact that our final contender seems to defy the laws of astrophotography retail. 12:21 The Laida filters are 1.25 inch, which does mean they are smaller than the others. 12:25 But even if you buy the two inch versions of them, the price is still shockingly cheap. 12:30 Hence why they score a 10 out of 10 in terms of cost. 12:33 Speaking of which, when it comes to scoring the imaging quality, the Antlia filters are indeed top drawer. 12:38 No filters outperformed them. 12:41 They walk the walk, earning an impressive 10 out of 10. 12:45 Meanwhile, the ZWO filters, I'm afraid, scored just a tad less than the Altair filters. 12:50 Literally just half a point. 12:51 It was a North America Nebula image that swayed my final decision on this one. 12:55 Both filters provide you with great results and are welcome additions to the narrowband imaging world. 13:00 For the Scorpio images, I think I might be being a little too harsh here and showing a bit of favoritism to the Antlia filters, but I've given them the edge here and scored the Scorpio set 9 out of 10. 13:10 Even though for the most part, their two sets of images feel inseparable. 13:14 And lastly, the Laida filters put up a good fight. 13:17 I won't be scoring them harshly on the corner vignetting since they are just 1.25 inch filters, but the star haloing and the general noisiness make this our lowest rated images of the set.

13:27 In conclusion

13:28 And with that being said, in conclusion of my test for what is the greatest astrophotography filter set, I have found that The ZWO filter set provides the worst value for money.

13:33 Worst value, ZWO

13:37 Far and away. 13:38 Maybe it's just here in the UK, but the cost is surprisingly high.

13:42 Third place tie, Laida + Altair

13:42 Then for the third place, we actually have a tie between the Laida filters and the Altair, both providing a lot of star for your book. 13:50 I think the Laida is a must-have as a cheap handy set. 13:53 But the Altair filter set is certainly the most affordable and effective set on the market right now.

13:57 Second place, Antlia

13:58 Its prices are significantly better than the competition. 14:01 In second place, and not by much, are the Antlia filters. 14:05 Premium images also mean premium prices in this case. 14:09 If you want the suffocating light pollution in your area to be an afterthought, then these filters are an excellent choice. 14:15 But in terms of value for money and quality of images, the undisputed champion by a landslide are the Scorpio 2 inch 3 nanometre narrowband filters.

14:18 Undisputed champion

14:24 They tick every box for me and I've been using them every single night now for the last few months. 14:29 They feel like the most minor of downgrades from the luxury Antlia filters.

Check out more videos on the Antlia 2.5nm HSO

The $5,000 Telescope That's Closing the Gap With Hubble!?

30 Apr 2026

Is the ZWO FF110 Worth $1,499? (ZWO FF110 + ASI 6200MM + AM3N + ZWO LRGB)

2 Sep 2026

Should you buy it?

75/100 Stars for Your Buck

Pros

The best Ha frames in my comparison: it beat the Laida, Altair and ZWO filters and edged the Scorpio.
A 2.5 nm bandpass with 95% or more peak transmission at Ha and SII and 92% or more at OIII, on Antlia's figures.
Each filter comes with its own measured transmission and blocking data.
Gold rims and detailed labels: the most premium-looking filters I tested.
My Veil, Elephant's Trunk, North America, Rosette and Heart nebulae were shot through this set.

Cons

By far the most expensive set in my comparison.
The Scorpio 3 nm set came very close in my test for far less money.
Antlia recommends f/3.5 or slower, so very fast optics are out.
FLO sells the 2 inch filters one at a time.

In second place, and not by much, are the Antlia filters. Premium images also mean premium prices in this case.

Who the Antlia set is for

Heavy light pollution

Buy

2.5 nm filters take the worst of a bright town sky away; my comparison was shot under a full Moon.

Wants the best Ha frame I tested

Buy

It edged every other filter in my five-set comparison.

Owner of an f/4 to f/7 astrograph

Buy

It sits inside Antlia's f/3.5 or slower range; mine ran at about f/4.8 and f/7.

Value hunter

Skip

My recommendation is the Scorpio HSO 3nm: neck and neck in my test for a fraction of the price.

RASA or HyperStar owner

Skip

Antlia recommends f/3.5 or slower, so an f/2 system is outside its range.

1.25 inch filter wheel

Skip

My recommendation is the Laida HSO 5nm, the 1.25 inch set I tested.

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

Seven questions, answered

Questions about the Antlia 2.5nm HSO

Reviewed 18 May 2026 ·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

Are the Antlia 2.5nm filters worth the money? They gave the best Ha frames in my five-set comparison, but the Scorpio 3 nm set came very close for a fraction of the price. If light pollution is your main problem and budget is not, yes. The same target through each filter ↓
Antlia 2.5nm or Scorpio 3nm? On the same telescope, camera and night their Ha frames were neck and neck. I scored the Antlia 10 and the Scorpio 9 out of 10 for image quality, and the Scorpio won on value. The same target through each filter ↓
What focal ratio do the Antlia 2.5nm Ultra filters need? Antlia recommends f/3.5 or slower. My images were taken at about f/4.8 on the Askar SQA106 and SQA130 and about f/7 on the ZWO FF110. The specifications and the comparison table ↓
What comes in the box? The three filters, each with its own measured transmission and blocking data, according to Antlia. The specifications and the comparison table ↓
Where can I buy the Antlia 2.5nm set? FLO in the UK sells the 2 inch filters one at a time; Agena Astro in the US and Antlia's own store sell the set of three. The verdict, the readers and the sellers ↓
What have you imaged with it? The Veil, Elephant's Trunk, North America and Rosette nebulae on the Askar SQA130 with the ZWO ASI6200MM Pro, and the Heart Nebula on the ZWO FF110, all from my garden. What I captured ↓
What have I not tested on the Antlia set? I have not measured the transmission or bandpass, and my side-by-side test compares the Ha filters only.