UHC or O111

[Astroscot2]

Hello all.

Bit of a newbie question.

Im starting to do a bit more observing and have been pulling together and upgrading my visual kit over the last few months.  The skies from my back garden are not all that great at Bortle 6 and I was a bit disappointed with not being to see much detail even on the bright nebulae.  When I was doing a lot of observing back in my earlier days I recall using a UHC filter to enhance nebulae and remember being able to see stunning details in objects like the Veil and orion nebula using this filter.

I notice on the observing reports plenty of comments of observers using O111 filters to improve their views on Nebulae but few mentions of the UHC?  My thoughts are that O111 would only be useful on a few bright O111 objects and quite restrictive?

 

Would a UHC filter be better choice overall for enhancing views of all DSOs?

 

Thanks

Mark

Edited September 11, 2020 by Astroscot2

[Starwatcher2001]

Hi Mark,

Here's a good list of how objects respond to different filters. I think I might have originally found the link on here, so apologies to the original poster.

https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/

Edited September 11, 2020 by Starwatcher2001
made the link clickable

[Astroscot2]

5 minutes ago, Starwatcher2001 said:

Hi Mark,

Here's a good list of how objects respond to different filters. I think I might have originally found the link on here, so apologies to the original poster.

https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/

Looks like great lunchtime reading , thanks for the info.

 

Mark

[jetstream]

1 hour ago, Astroscot2 said:

My thoughts are that O111 would only be useful on a few bright O111 objects and not quite restricted?

 

Would a UHC filter be better choice overall for enhancing views of all DSOs?

No, the OIII would be the prefered filter for you, the list is very very long for what it will enhance. The UHC works well from very dark skies however if you want to see the Veil in all its glory for instance from variable sky darkness get the OIII.

Theres OIIIs then theres OIIIS - only 2 I would get is the new Astronomik or better yet the Televue, made by them.

[JTEC]

6 minutes ago, jetstream said:

only 2 I would get is the new Astronomik or better yet the Televue, made by them.

Totally agree. Tried all the usual suspects over the years (Lumicon etc)  I honestly think the Televue OIII beats them all. FWIW, if I had to pick one UHC filter for general use it would be the Omega NPB. 

[jetstream]

You know we have a very good copy of the NPB, very tight and works great.The H130 shows the North American neb (very easy) Flaming Star, Monkey head, Rosette, Swan etc etc with it. I also have an excellent older Lumicon UHC and the new Televue UHC or Nebustar I think its called.

Heres my impression: our NPB has excellent bandwidth but might be down on transmission compared to the 2 others- it is an excellent filter however. The old Lumicon feels tighter than the new Televue Nebustar but the Televue shows more?

I have compared the filters using a filterslide in my 15" dob over many many nights.

If you can get a good copy of the NPB for the money they are hard to beat, red stars and all.And yes totally agree the TV OIII is on the top of the heap.

[Louis D]

I have a 90s vintage Lumicon OIII that thankfully hasn't rusted (knock on wood) that does a fantastic job.  I've read that the problem with Lumicon is that they have had at least 5 different sources for their filters over the decades (and changed ownership recently), so it can be hit or miss on the used market as to what you will get.  It's a case of try before you buy used if possible.

I use my Lumicon UHC filter (also 90s vintage) as more of a light pollution filter in my Bortle 5/6 skies.  It helps increase contrast a bit, but no where near what the OIII does.

I also have a Zhummel OIII that is pretty pathetic.  It's not even as good as the UHC.  However, I only paid $14 for it on clearance.  Don't skimp on OIII filters.  The cheap ones don't really work at all.

[John]

I have both O-III and UHC filters. The O-III filters get used a lot more.

Good advice above on not economizing on these sorts of filters as well. The low cost ones are noticeably less effective from my experience.

[Don Pensack]

After using 52 different nebula filters (in a 12.5" scope at a dark site) for the last 3 years (and unloading all but 13 of them by now), I have a few comments:

Broadband.  Unless you observe from a very dark site and just want a trace more contrast, skip it.  Lumicon Deep Sky or Baader UHC-S here.

Narrowband, (UHC-Type).  Essentially the universal filter.  It will enhance the large H-II gas clouds like M8, M20, M17, M16, M42 better than an O-III and still does well on the O-III targets.  Lumicon UHC Gen.3, Astronomik UHC Visual, TeleVue Bandmate II Nebustar, or DGM NPB.

O-III.  Since this works well on supernova remnants, planetary nebulae, and Wolf-Rayet excitation nebulae, it's an important one to have.  However, it's not that good on the large hydrogen gas cloud nebulae,

so it's a second choice.  You will want to have one as well as a narrowband.  Lumicon Gen.3 O-III, Astronomik O-III, TeleVue Bandmate II O-III.

H-ß.  This definitely helps the large faint hydrogen clouds like NGC1499, IC434, and a number of Sharpless nebulae.  I think it is useful only at a dark site, though, and in 6" or larger apertures.  Mainly because its narrow bandwidth

makes the field quite dim.  Astronomik H-ß, TeleVue Bandmate II H-ß

[I added some recommended ones at the end of each category]

A few additional points:

--filters require dark adaptation.  That's 30-45 minutes outside away from lights.  Otherwise, they won't perform well.

--filters require larger exit pupils--2.5mm or larger.  They are low power accessories, for magnifications up to 10-12x/inch maximum.

--don't expect miracles.  Enhancement is reduced in heavy light pollution.  Truth: there is no light pollution reduction filter for objects with broadband spectra like stars or galaxies.  We're just lucky we can use narrowband filters on emission nebulae.