FILTERS where to begin, quality vs. price and brands

I have been poking around about filters in the forums trying to learn more and figured I should start here. I have been following a post from a person asking about advice about Astronomik and Antlia which to buy. Instead of derailing their topic, I figured I should start a new one. I’m imaging with a DSLR right now but plan on moving to mono.

There is a big difference in cost between filters. A person in the other post gave great advice about trying to match filter thickness due to back focus, so this obviously would be a factor for those who are buying new filters or plan on using different brands.Both Astronomik and Antlia seem to be middle of the road in quality and price, and I think these two brands will be in my price range. Both of these brands are the filters I may be considering purchasing, both not committed yet. There is a massive difference in the price of Chroma filters compared to Astronomik and Antlia. Is the difference in quality of Chroma that much more in comparison to price? What other brands are of higher quality? I have read Deep Space Imaging Primer and plan on going back to this, but is there any other website or book recommended that have more information for those who are interested in this topic?

Generally, you want to consider a few things:
- Filters to be parfocal, so focus don't need adjustment between filter switches. Usually if you are buying a filter set of a same brand, they are parfocal but it's best to carefully read the description
- Keep in mind filter thickness when setting backfocus distance - filters of same thickness will surely be more convenient
- Consider filter bandwidth (https://www.cloudynights.com/topic/724945-narrowband-imaging-at-fast-f-ratios/)

Regarding the brands - I initially got ZWO LRGB and narrowband filters (branded as "new", I guess it was 2nd generation of NB filters produced by ZWO) and while LRGB was just fine, the NB ones resulted in terrible halos near brighter stars. Then upgraded it all to Chroma and had zero problems since. Not sure about the other brands, though, but ZWO ones are a good indication of what not to buy.

I was wondering about this a little while ago, trying to decide if it was better to pony up the big bucks for Chroma filters or not.
So I used the search function and looked at around 100 randomly selected award winning images (IOD, Top Pick or Top Pick Nomination) taken using a popular monochrome camera and posted during 2024. Then I noted what filters were used.

The results were
49% Antila
34% Other (ZWO, Astronomik, Baader, etc, or some combnation)
10% Chroma
4% Astrodon

So I bought the Antilas.

You might wish to do the same kind of research using a setup similar to what you are contemplating. The Astrobin tools are pretty nice.

Good luck with your search.

Brett Joslin:
Is the difference in quality of Chroma that much more in comparison to price?

There is a difference in quality and in the quality of the customer service you get from Chroma as well.

Russ Rybicki:
The results were
49% Antila
34% Other (ZWO, Astronomik, Baader, etc, or some combnation)
10% Chroma
4% Astrodon

Yes, more people will buy cheaper filters. That doesn't make it the right choice necessarily. But, if folks are happy with the Antlia filters then that is great. The last time we tested those filters (many years ago) we elected not to go with them as they suffered from halos fairly bad.

Dark Matters Astrophotography:
Russ Rybicki:
The results were
49% Antila
34% Other (ZWO, Astronomik, Baader, etc, or some combnation)
10% Chroma
4% Astrodon

Yes, more people will buy cheaper filters. That doesn't make it the right choice necessarily. But, if folks are happy with the Antlia filters then that is great. The last time we tested those filters (many years ago) we elected not to go with them as they suffered from halos fairly bad.

I think the takeaway isn't that "more people buy them" (while accurate), it's that you can produce award winning images with them. I don't think you'll find too many people arguing that Antlia is better than Chroma or Astrodon, but too many people argue that you need the best or nothing.

Think of it like complaining that a Ferrari isn't as fast as a McLaren... While technically accurate, people driving a Honda Civic will be extremely happy with the Ferrari as an upgrade.

I think the takeaway isn't that "more people buy them" (while accurate), it's that you can produce award winning images with them. I don't think you'll find too many people arguing that Antlia is better than Chroma or Astrodon, but too many people argue that you need the best or nothing.

Think of it like complaining that a Ferrari isn't as fast as a McLaren... While technically accurate, people driving a Honda Civic will be extremely happy with the Ferrari as an upgrade.

Sure, however I would not consider the IOTD process the be all end all of what is good data and what is not. The over-indexing on IOTD is heavy for some reason, but it should not lead people to make product purchase decisions over it. If the filters provide the quality of data someone is happy with, then that is the ultimate goal. In our experience this has really only happened with Chroma filters consistently.

My experience is that there is a difference in expensive filters vs other known brands vs cheap filters.

But the difference is not as drastic as you would think,

Example
Expensive Optolong L-Extreme (lets just pretend that is a 10/10) for the specific need and example
ZWO or Astronomik might be an (8/10)
Cheapest stuff (3/10)

This varies a bit based on your scope, type of filter, etc. But my experience is the (medium priced stuff) is not just as good as the high end, but for what your are paying you get a much better value.

I have a couple really expensive Optolong and Idas filters, that perform great, but I could have saved a couple hundres bucks on each of them and still got the job done.

I feel like "elite" filters are probably beyond my eyes and beyond my skill level.

I dont snowboard any better on a custom 3000 board vs a 600 Burton, but the garbage no namer would be noticed.

Just an opinion but I think paying nearly $2000.00 for a set of mounted 2" LRGB filters is ridiculous. I used to be in the optics industry and can see no reason why a simple, wide bandpass filter should cost so much, unless you are used to marketing to Universities, private corporate entities and the government where price is no object. Even if the glass was certified as 1/20 wave flat it's hard to justify. I do know that Chroma had a very large price increase in the Astronomy line of filters after they had a change of leadership at the CEO level, in some cases pricing has doubled. I can't imagine that the quality increased by a factor of 2 at the same time. I'm am sure they are good filters but honesty!

Other people may or may not care about this and that's fine.

To me, there is some value to be had in supporting a local (in my case American) company. Within reasonable price differences, I am happy to do that to maintain this competency here. It is also the reason I have not hesitated to pay more for my mounts and one scope. There is value to be had in supporting craftsmanship or just a local business which we too often forget in these days of online purchases.

When value is equal I will always buy local, (In my case that happens to be American too), but its has to be at least close on a value level.

Small pitch for Astronomics, I own 3 of their refractors, which I love. They are a US company, with great service, and quality products.

I can't say their stuff is all American made, but lets be honest there isnt a lot of American Made AP gear anyway.

But to play devils advocate, its hard to argue with the value in the ZWO ecosystem, asiair, AM5 mount, EAF and EFW combos are pretty amazing and for the price not much made in the US is close.

Chroma, Stellarvue, Astro Physics, SB, Losmandy, PlaneWave, and if the information I have is true the return of FLI. Plenty of American made goods in AP. Whether or not that is all that important depends on the buyer. This isn’t an American centric hobby at all so for many it’s a useless point to make.

For me it was more about halo control than anything else. More specifically with the SHO, zwo brand halo pretty significant. Svbony suprized me with their 5nm, these cost less than the zwo and seem to perform better at halo control. The Antlia are nice and so are the Astrodon and Chroma. I don't do a whole lot with RGB so harder for me to speak to that. I will say that I own all the brands I've mentioned and I think the Antlia Edge 4.5nm SHO are excellent for the price and compete pretty well with upper tier brands.

I read along the way a lot of optics are made by some of the same companies. Whether that is true or not I don’t know, could that be the case with filters?

With quality in mind some countries manufacturing standards are higher than others. Could this be why some people see halos and others not?

would one recommend buying larger filters even though you may not need them now. As an example let’s say you shoot with a micro APSC would you just buck up for the 2” filters to future proof you gear?

Dark Matters Astrophotography:
Chroma, Stellarvue, Astro Physics, SB, Losmandy, PlaneWave, and if the information I have is true the return of FLI. Plenty of American made goods in AP. Whether or not that is all that important depends on the buyer. This isn’t an American centric hobby at all so for many it’s a useless point to make.

Agreed, I love that I can share the hobby with people all over the world.

Brett Joslin:
Is the difference in quality of Chroma that much more in comparison to price?

In many areas, not just filters, when you are already at the top, any incremental improvement can cost a lot. So when you compare two already-very-good filter manufactures, it shouldn't surprise anyone that the better one is much more expensive.

That being said, it's up to the buyers to decide whether Chroma's price is justifiable. Their prices were much lower before, which means their current pricing is completely a marketing decision.

Personally, I wouldn't consider Chroma for my small portable telescope. It's just too much. But when I was constructing a remote observatory whose total cost approaches 0.1M USD, the cost of Chroma filters becomes relatively insignificant. We saw all kinds of problems on other filters that we had, and most of the problems went away after we switched to Chroma. So for this remote observatory, it's a very worthwhile investment.

For personal small telescopes, my approach probably would be to start with filter sets that are affordable with above average quality (based on people's feedback). If it works well, stick to it. If you see problems, then study it and consider more pricy replacements.

Wei-Hao Wang:
Brett Joslin:
Is the difference in quality of Chroma that much more in comparison to price?

Personally, I wouldn't consider Chroma for my small portable telescope. It's just too much. But when I was constructing a remote observatory whose total cost approaches 0.1M USD, the cost of Chroma filters becomes relatively insignificant.

For personal small telescopes, my approach probably would be to start with filter sets that are affordable with above average quality (based on people's feedback). If it works well, stick to it. If you see problems, then study it and consider more pricy replacements.

makes logical sense

I wouldn't put too much weight into making sure filters are all the same thickness and therefore parfocal. I've never seen a set that claims to be parfocal actually live up to that. Maybe at f8 but certainly not at speeds I find myself at, f2.8-f4.

Turns out it doesn't matter. Set up your filter offsets properly and never worry about it again.

Now there is a bit of credence to matching filter thicknesses to stay within a certain backfocus tolerance range. If you see a noticeable different with .25mm of change in backfocus then a mix of 1mm and 3mm thick filters might be enough to throw that off as the thickness of the filter glass will change the light path a bit. Enough to matter? Depends on your setup. For most people, no.

Hi Brett - this question will be asked forever, and it should be. What was true 5 years ago might not be true today - technology progresses faster than we do.

Chroma make filters. It costs a ton of money to produce/employ specialists.
https://www.chroma.com/

I'll add Alluxa to this:
https://alluxa.com/

I'll also add edmundoptics - fun to browse the zillions of optical things available:
https://www.edmundoptics.co.uk/

I have a 0.5nm Ha from EO and it proved invaluable for my Solar astronomy. I'm not into DSO, but we all need filters.
This 0.5nm Ha cost me £1200 IIRC. "Stupid money" for soft coated (T 45%) filter. But it was essential to my needs.

Most astro equipment vendors do not have their own filter manufacturing facilities - they will outsource to the likes of Alluxa, Chroma, others.
They order a large batch and the cost savings are passed on to us.
However, you can't expect them to QA down to ± 0.01% for thousands of filters at a "really good price".
If you buy individually from the horses mouth then then yes, you can expect "perfection".

As for parfocal - I'm going to think my own mind on this matter.
Where to start.
Resolution is proportional to telescope aperture; the bigger the better.
However, resolution is also proportional to wavelength; blue packs more lines per inch than red.

A 90mm refractor imaging 393nm (Ca K) has the same resolution as a 150mm refractor imaging 656nm (Ha).
My point is not about focus. My point is "critical sampling" - how well that splodge of an Airy disk maps to camera pixels.
That splodge of an Airy disk gets fatter as the wavelength increases.
Which means "critical sampling" is a variable and not a constant.
As wavelength increases (red...infrared) the focal length or ratio needs to be brought down, to maintain this "critical sampling".

I mention this as I've seen many "my red stars are always bloated".
Achromats obviously focus R/G/B at different places. I don't see how parfocal filters help here, unless they are also "lenses".

What "bloats" is the fact IR/NIR Airy disks are bigger than blue ones.
Without reduction of "f" then the fatness of the Airy disks will expand on the sensor.

This is my opinion and may not be correct :-)

Ed Astle:
Hi Brett - this question will be asked forever, and it should be. What was true 5 years ago might not be true today - technology progresses faster than we do.

Chroma make filters. It costs a ton of money to produce/employ specialists.
https://www.chroma.com/

I'll add Alluxa to this:
https://alluxa.com/

I'll also add edmundoptics - fun to browse the zillions of optical things available:
https://www.edmundoptics.co.uk/

I have a 0.5nm Ha from EO and it proved invaluable for my Solar astronomy. I'm not into DSO, but we all need filters.
This 0.5nm Ha cost me £1200 IIRC. "Stupid money" for soft coated (T 45%) filter. But it was essential to my needs.

Most astro equipment vendors do not have their own filter manufacturing facilities - they will outsource to the likes of Alluxa, Chroma, others.
They order a large batch and the cost savings are passed on to us.
However, you can't expect them to QA down to ± 0.01% for thousands of filters at a "really good price".
If you buy individually from the horses mouth then then yes, you can expect "perfection".

As for parfocal - I'm going to think my own mind on this matter.
Where to start.
Resolution is proportional to telescope aperture; the bigger the better.
However, resolution is also proportional to wavelength; blue packs more lines per inch than red.

A 90mm refractor imaging 393nm (Ca K) has the same resolution as a 150mm refractor imaging 656nm (Ha).
My point is not about focus. My point is "critical sampling" - how well that splodge of an Airy disk maps to camera pixels.
That splodge of an Airy disk gets fatter as the wavelength increases.
Which means "critical sampling" is a variable and not a constant.
As wavelength increases (red...infrared) the focal length or ratio needs to be brought down, to maintain this "critical sampling".

I mention this as I've seen many "my red stars are always bloated".
Achromats obviously focus R/G/B at different places. I don't see how parfocal filters help here, unless they are also "lenses".

What "bloats" is the fact IR/NIR Airy disks are bigger than blue ones.
Without reduction of "f" then the fatness of the Airy disks will expand on the sensor.

This is my opinion and may not be correct :-)

Your comment got me thinking about matching filters to resolution sampling. This is a new thought for me and gives me a lot to chew on.

In my experience, the Astrodon/Chroma filters handle Halos better than any of the mid tier and lower filters. That said, Halos are a problem on the brightest stars.. so most of your targets will be just fine with the mid level filters.

In regards to parfocal/filter thickness, if you plan on using an OAG, you need everything to be really close. If you try to mix 2mm and 3mm filters.. your OAG will be out of focus for one set or the other. Regardless of OAG or not, I recommend using the same brand/model/set for all the filters.

Side note: Astrodon is dead. You can still find them on the used market and they are quality filters but new ones are no longer available.

Side note: Astrodon is dead. You can still find them on the used market and they are quality filters but new ones are no longer available

Farpoint says they sell Astrodon them but on back order but can be added to a waiting list 6-8 week turn around. I wonder if that is just old info?

I have to see a significant visible difference to justify the significant difference in price. When I was researching, I remember on CN seeing a detailed head to head comparison of various filters at that time, both expensive and economical. I ended up going with the economical Optolong LRGBHOS set because I couldn’t visibly see a difference in the comparisons. I’ve been happy with my decision because I could buy two sets with filter wheels to accommodate my setups vs one set of the expensive filters. I’ve been in Manufacturing technical sales for 30+ years and understand branding vs industry standards, and how that can be manipulated successfully in the market place.

Please note that very narrow narrowband filters may become less useful if you move to faster optics.

I have a set of 2" mounted 3nm Chroma that were excellent with my Edge14 w reducer (f/7.7) but useless with my Hyperstar (f/1.9).

BTW, the Chromas are for sale ...

Well I figured for those who are researching and come across this post I’m adding a link for a halo and customer service issue with Astronomik.

https://www.astrobin.com/forum/post/186124/

I've been using Antlia for about a year now. I started out with their 7nm SHO 36mm unmounted. Even though the retailer's website said they may exhibit halos on long exposures, I noticed none. I then bought their RGB 36mm unmounted and they are fine too.

I recently got the SVX130T and bought a new set of Antlia filters LRGBSHO 2" mounted. I haven't used them much, the only Halo I got was with the Oiii filter shooting Alnitak, that doesn't concern me because a lot of filters will do that around that Magnitude 1.8 star.

Would I buy Chroma? Sure, one day, but for $2000 for just the LRGB set, another ~$3000, for narrowband, many of us just can't do that, I mean I could… but that's hard to justify unless the Antlia just aren't performing, but they do just fine, and you get the full set LRGBSHO (3nm) for under $2000.

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