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I have a 10" dob and was wondering if the Lumicon is better than the Orion.

Lumicon, when I spoke with them on the phone, seemed 'underinformed' regarding the necessary aperture to be used with this filter. Their website says 12.5" or something to that effect..

Can I also use a 5mm exit pupil with this kind of filter?

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I think the minimum aperture for the H-Beta depends on what you are viewing and the viewing conditions. I have used a 2" H-Beta filter just held up to my eye to see things like Barnard's Loop, the Lambda Orionis complex, and the California Nebula (from a dark sky site BTW). In my 100mm f/6, I can see faint detail in sections of Barnard's Loop at very low power (15x) using the H-Beta, and have glimpsed the Horsehead on a few occasions, although that particular object is rather marginal in such an aperture. With larger apertures, more H-Beta objects do become visible, although most are quite faint. Here is a list of the more common targets for the H-Beta filter:

..........USEFUL TARGETS FOR THE H-BETA FILTER..........

While the H-Beta is probably one of the less-used nebula filters, the commonly-expressed idea that it works only on a handful of objects is not true. Here is a list of the more prominent objects that the H-Beta may be at least somewhat useful on. Some may require larger apertures, but a few have been seen from a dark sky site by just holding the filter up to the unaided eye and looking at the sky). Some of these will also be helped by a narrow-band filter like the Lumicon UHC.

1. IC 434 (HORSEHEAD NEBULA)
2. NGC 1499 (CALIFORNIA NEBULA, naked eye and RFT)
3. M43 (part of the Great Orion Nebula)
4. IC 5146 (COCOON NEBULA in Cygnus)
5. M20 (TRIFID NEBULA, main section)
6. NGC 2327 (diffuse nebula in Monoceros)
7. IC 417 (diffuse Nebula in Auriga)
8. IC 1283 (diffuse Nebula in Sagittarius)
9. IC 1318 GAMMA CYGNI NEBULA (diffuse nebula in Cygnus)
10. IC 2177: (Diffuse Nebula, Monoceros)
11. IC 5076 (diffuse nebula, Cygnus)
12. PK64+5.1 "CAMPBELL'S HYDROGEN STAR" Cygnus (PNG 64.7+5.0)
13. Sh2-235 (diffuse nebula in Auriga).
14. Sh2-276 "BARNARD'S LOOP" (diffuse nebula in Orion, naked eye)
15. IC 2162 (diffuse nebula in northern Orion)
16 Sh2-254 (diffuse nebula in northern Orion near IC 2162)
17. Sh2-256-7 (diffuse nebula in northern Orion near IC 2162)
18. vdB93 (Gum-1) (diffuse nebula in Monoceros near IC 2177)
19. Lambda Orionis nebular complex (very large, naked-eye)

In addition, a number of the brighter nebulae like NGC 7000 or M42 will respond to H-Beta use for revealing certain specific detail, although other filters may provide a somewhat better view overall.

Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info

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I've tried both of those filters, Dave B. I would almost put the Lumicon 'equivalents' a cut just above, but not by that much. I am fond of the Ultrablock on emmission nebulae.

I spoke with Orion tech support today and the H-Beta they sell is 14-16nm wide....this is much wider than Lumicon's 9nm passband centered on H-Beta.

Thanks Mr. Knisely. Can I use a 5mm exit pupil with an H-Beta filter through my 10" f/5 dob with success? How dark a sky will be required of me to use the filter through my scope effectively at that exit pupil? The Horesehead obviously would be one of my first targets. It is great to know that this line filter has been useful on so many more targets than generally advertised.

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These narrowband and line filters tend to work better at between 3.5x and 9.9x per inch of aperture (7mm to 2.5mm exit pupil), so a 5mm exit pupil should be fine. For viewing any faint nebula, you will want as dark a sky as possible, but I have seen the Horsehead in my NexStar 9.25 inch SCT from my home under magnitude 5.6 skies using my Lumicon H-Beta, so it is possible. However, the object was *very* dim and was not as easy to see as it is from my dark sky site. You really have to take steps to get and stay fully dark adapted, and that is tough to do under bright sky conditions. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info

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david, have you had a chance to look at the orion h-beta yet? no one in our club has had the balls to order one yet. we tried the orion O3, and the ultrablock.

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I have yet to try the Orion H-Beta, but from what I hear, it is a bit broader than the Lumicon H-Beta. Interestingly enough, I have found that under dark sky conditions, the DGM Optics NPB sometimes provides almost as much of a contrast boost on the Horsehead that an H-Beta filter does. It isn't a replacement for the H-Beta, but if you can only get one filter, the NPB would be a very good choice. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info

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David- thanks for that list!

Who has the best price on 2" H-Beta filters?

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Well, you kind of have to shop around, but if you want the most consistent quality, you may want to go with outfits like Lumicon or Astronomik (both around $200) rather than some no-name brands. For some other prominent names, the Baader H-Beta is somewhat more expensive at around $235, while the slightly wider Orion H-Beta is around $140. The Thousand Oaks H-Beta (their "type 3") is around $179. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info

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Dave:

I have an Orion H-Beta filter, but haven't used it yet. I am planning on using it with a new 15" Obsession when Orion is better situated.

I'll kick up a report if no other reports exist by the time I get around to using it. Like other recent vintage Orion filters this one is made in Korea.

Cheers,

Jim

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I recently aquired the NPB filter! It is terrific and one of amateur astronomy's best kept secrets in my opinion.

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Well..looks like you already did some additional research on that filter! The DGM Optical NPB filter is everything and more than the Lumicon UHC filter.

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Well, while the NPB is a better filter than the Lumicon UHC, it is not exactly enormously better. I find the UHC to yield fairly similar views to the NPB, so one really can't go wrong getting it. The NPB does have a slightly lower price, a bit of an edge in contrast, and somewhat better overall color balance and star images, which is why I generally recommend it over the UHC. However, strictly from a performance point of view, the UHC and Orion Ultrablock are not bad either. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info

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