Filter Performance Comparisons

[pakarinen]

@Maiden and anybody else who's interested in a nebular filter review:

https://www.prairieastronomyclub.org/fi ... n-nebulae/

I have no idea if this info is reliable or not. Buyer beware.

[Graeme1858]

Moved from Off Topic/What have you been up to lately.

[kt4hx]

The author, David Knisely is a well-known amateur and very active over at Cloudy Nights. He utilizes filters extensively and does have a lot of experience with them. While everyone may not agree with his assessments, I have found his information generally useful over the years. Of course, as with any review/comparison, some personal brand bias tend to creep in, which is understandable as we all like what we like for our own personal reasons. But overall I see the document as well written and very useful.

[notFritzArgelander]

It would be interesting to hear what [mention]j.gardavsky[/mention] thinks of this. He's quite an expert on this boards on filter use.

Knisely has his opinions. I generally find UHC filters to be much less useful and H-beta filters much more useful than he does. I've stopped using UHC filters altogether. I am considering the Altair tri and quad band filters but I'm pretty happy with what I've got. I have the Baader narrow band filters. [mention]j.gardavsky[/mention] prefers other brands.

[kt4hx]

JG has voiced his opinion on Dave's article over at AF in times past. He told me that he felt Dave is too heavily weighted toward Lumicon. I very much respect JG's opinion because I know he comes from an optical background. I think both give sound advice, but both have their personal favorites and viewpoints, which one should take into account. Given that my observing is heavily slanted toward galaxies, my use of filters is very limited overall. Nonetheless I do have broadband and narrawband UHC filters, O-III and HaB filters in my case just in case I need them during a session.

[j.gardavsky]

Thank you not_Fritz and Alan for your inputs!

As most of my recent observing projects have been on the interstellar matter (ISM, IFN, LBN), my preferences regarding the filters have been changed for the time being.

Most of the diffuse nebulae not included in the NGC/IC catalogs respond to the H-Beta filters. And it has been the recommendation of not_Fritz, why I have added to a pair of the Astronomik H-Beta filters, also a pair of the narrow pass-band Baader H-Beta CCD filters, even if the Baader H-Betas have a lower transmission, but their contrast often wins.

Lots of the Lynds LBN bright nebulae, not included in the popular catalogs are just faint HII ionized hydrogen glows, and so are the Gaze-Shajn nebulae. As just one wavelengths (H-Beta) of the blue Balmer series of HII is in these cases not enough for the visual perception, I have been increasingly using the wide passband 400nm - 510nm Baader blue(RGB)CCD filters, which pass the light of H-Beta, H-Gamma, and at least some visible pohotons of H-Delta. Herewith some difficult nebulae can be pulled out of the invisibility.

Regarding the OIII filters, I am using the wide pass-band (12nm) Astronomik, the narrow pass-band Baader (10nm), and the ultra narrow pass-band (5nm) Astrodon.
The most use finds the Baader OIII:
On yesterday night I have seen the Wolf-Rayet Nebula WR 134 in Cygnus through the Baader OIII filters mounted on the 15x85 binoculars.
viewtopic.php?p=31643#p31643
Off course, the binoculars have shown just a faint disc, but I have been quite excited.

My observing project on the nebulae in Lacerta has been completed, and I will post it during the next days.

On a side line,
the numerous filter shoot-outs as published on the web apply fairly well to lots of the NGC/IC popular nebulae.
However, the filters choices are dictated ad ultimum through the astrophysics of the nebulae.
And the two principal mechanisms of bringing a volume of gas to a glow are the UV ionization by some stars, like the OB associations stars,
and the collision ionization (OIII doublet) in the expanding shells of the panetary nebulae, Wolf-Rayet nebulae, supernova remnats, and in the star birth regions.

Clear skies,
JG

[pakarinen]

Any thoughts on Astronomik UHC-E?

[j.gardavsky]

Any thoughts on Astronomik UHC-E?

It is just an Economy version of the Astronomik UHC.

The Astronomik UHC has been exclusively useful when hunting the spiral arms and the star birth regions in the Triangulum Galaxy M33. Otherwise seldom used.

When getting started to use the nebular filters, I would again take the Baader OIII visual 10nm to begin with.
On yesterday night, even if under mediocre observing conditions due to the smoke we are "importing" from the U.S. forest fires, I have enjoyed through a pair of these Baader OIII filters mounted on the 15x85 binoculars the views:
Sh2-123 (Wolf-Rayet nebula), North America, Pelican, Cirrus/Veil, Crescent, Dumbbell, and Ring nebulae.

As the quality of the filters is for lots of the deep sky objects even more decissive than the quality grade of the eyepieces, it is often better to spend more for the right choice of a filter, than to upgrade later.

Best,
JG