Which SHO filters?

I have Chroma filters, they are very good however not so cheap, especially considering they are 50 mm
Luckily i bought the SHO before the pandemic. 
However, I had regrets because I didn't buy the LRGB as well and recently they were more expensive…

If i had to buy new filters probably i would try the Antlia
Always as narrow as possible

Just consider that if you use OAG or you plan to OAG one day, buy all the same brand to be as parafocal as possible…
I learned it the hard way when I coupled the SHO from Chroma with the Astronomik LRGB Deep Sky Set…

AstroDivers:
I have Chroma filters, they are very good however not so cheap, especially considering they are 50 mm
Luckily i bought the SHO before the pandemic. 
However, I had regrets because I didn't buy the LRGB as well and recently they were more expensive...

If i had to buy new filters probably i would try the Antlia
Always as narrow as possible

Just consider that if you use OAG or you plan to OAG one day, buy all the same brand to be as parafocal as possible...
I learned it the hard way when I coupled the SHO from Chroma with the Astronomik LRGB Deep Sky Set...

Ooh good point about keeping things parfocal with the same brand.  Chroma seem really great, but I’d have to decide which kidney to sell!
Thanks!

The band pass on the Lum filter and the Blue filter don’t cut off until we’ll below 400nm. This is pretty deep in the blue range. The Antlia and Astronomik blue filters cut off around 425nm and so does the Astronomik L3 lum filter. This helps to control the blue halos that many doublets have. But, if your scope is well corrected then the ZWO filters are just fine. 

None of this matters for SHO, just LRGB imaging.

I really like my 6nm Astronomik. Works fine, no halos.

I use Chroma filters, was fortunate to buy them when Chroma was new into the astro market and wasn't charging an arm and a leg. I couldn't be happier with them. I'm sure there are now cheaper choices that come close enough that it doesn't matter. If you are serious about narrow band, I'd get the 3nm filters, whichever brand you get.

The thing I will say about Chroma is that they stand behind their product. I discovered a minor halo problem in my OIII filter three years after I bought it and they exchanged it, no questions asked. I know a friend who had a very similar problem with his Astrodons and they made all kinds of excuses not to exchange the filter.

By the way, Chromas are not quite parfocal, though they are close. I do have to refocus between filters.

Edit: I see the point @AstroDivers made was from an OAG standpoint. The  Chroma LRGB and SHO filters are definitely parfocal enough that you will have no problems with switching filters and using an OAG. The one exception is their LoGlow filter, which is 1mm thick versus the others are 3mm thick. The LoGlow definitely needs me to reposition the OAG if I am switching to it from one of the other seven filters.

Brian Puhl:
I feel like photographic evidence is alot better than saying " I'm happy with my filters!"

It is a good point that photographic evidence is best. The nice thing about AB is that you can click on someone's name and it takes you to their image gallery, which offers a good way to judge if their opinion of what is good equipment matches your expectation 

Brian Puhl:
I have antlia 3nm and I'm perfectly happy with them.   They are sold with a disclaimer against halos, which seems discouraging at first, but they're rather good.  Here's a screenshot of the only target I've shot twice with the same imaging train but different scopes.  52 Cyg isn't the brightest, but it can expose optical issues.   The top two are Ha/Oiii shot with my 8" newt and Nexus coma corrector putting it at F/3.   Most of the diffraction you see is because my mirror ended up really dirty, otherwise maybe an ever so slight outline of a halo.  Optics were misaligned a bit as well, but for science this works.
  Bottom set, the only thing that changed is it was taken with an Espirit 100 instead, at F/5.5.   Both are untouched, auto-stf stacks.


Hopefully this helps you a bit.     I feel like photographic evidence is alot better than saying " I'm happy with my filters!"

Thanks for sharing the comparison, very cool! AB certainly has tons of really spectacular photos with these Antlia filters

I use Antlia 3nm (Sii and Oiii), 4.5nm Ha and the LRGB V Pro set, I made the upgrade from ZWO gen II at the beginning of the year.
With the ZWO filters I had huge problems with halos, on certain targets they were extremely bad. My Antlia filters has yet to show any kind of halo on any of the subjects I have imaged and they have been used on fast optics (F/2 and F/2.8) without any issues. 

The only thing I do regret is not getting the 2" or 36mm set right away to avoid making the purchase twice for a larger sensor camera.

I have both, the  CHROMA 3nm for the ASI 1600MM, and ANTLIA 3nm for that Toupcam, IMX571 sensor that needs 32mm. did a side by side comparison using Alnitak…

my 5C: 3nm all the way, better contrast, better exclusion of light pollution. 

CHROMA are excellent, essentially no halos 
ANTLIA are excellent, minimal halos that evening

conclusion: Chromas are a bit better, but a LOTLOT more expensive.

suggesting 3nm ANTLIA

I use Astronomik SHO 6nm 36mm matched with their Deep-Sky RGB filter set and their L3 luminous. All of these filters are parfocal that leads to a quick transition between filter changes. I'm old school and still use a Bahtinov mask with the Lum to focus then switch to the NB filters before collecting subs. The key is getting a complete set that is parfocal. I have owned many different sets of filters and couldn't be happier with my Astronomiks with their nice balance of price/performance.

Buy the best/narrow filters you can afford as it will show up in your images. And remember that diameter size matters when it comes to future-proofing possible camera sensor upgrades.

CS!

Michael Gruenwald:
makes no whatsoever to me, my routine is now to refocus at filter change or every hour, whatever comes first…

The focusing after each filter is not the issue - as you note, you need to do it with any filter change. But if the optical thickness change is meaningful, you may have to reposition your OAG after a filter change. This is a pain. Your back focus may be affected too, if you have tuned it to be optimal for a certain optical thickness.

Bob Lockwood:
Per Chromas website, all their filters are 3mm thick and have a 97% transmission, or better.
Antlias filters range from 2 to 3mm depending on the filter and transmission ranges from 85 to 95% depending on the filter.

This is significant. We have talked about halos. I assumed the transmission numbers were the same. Antilla, on their website, claims transmission numbers of ">88%" for the H-alpha. Chroma's measured transmission for their H-alpha filter is 99.1%. With this difference, I would say the Chromas are not just a bit better, but meaningfully better. You get what you pay for or less, I guess.