In the current IC 443 thread, there was a sidetrack into the usefulness of the H-Beta filter. It seemed more appropriate as a separate thread in its own right, so here it is.
Some of us old-timers may remember Lumicon advertising referring to H-Beta filter as "the HorseHead filter". And probably a lot of us bought it based on that alone. I know I was one of them!
David Knisely published a list of other nebula where the H-Beta filter works. I suppose "works" is defined by Expectations, going down the list I had some nice successes and some so/so results where O-III or UHC was more revealing. In fact, I sold my H-Beta (and the others) to consolidate on the DGM NPB filter. But who knows, I may find reason to try it again
What observations have you made with the H-Beta, and what were your impressions? Which objects in the "Knisely Catalog" are the H-Beta Stars? To get the party started, my logged H-Beta specific observations:
- Sh 2-84, Sagitta, Jun 8, 2011, R12.5, Home: Perhaps transparency not as good as I thought. Barely detected with the UHC filter, seemed to react slightly better to H-Beta.
- Sh 2-9, Scorpius, Jun 22, 2011, R12.5, Mingus: Responded to H-Beta filter. Easiest to detect when moving scope E-W. N and S edges not distinct.
- Sh 2-115, Cygnus, Jul 20, 2011, Star12, Home: Relatively easy to see w/out filter. The nebula will respond to H-Beta and O-III but was best with the UHC.
- Sh 2-125, Cygnus, Jun 4, 2011, R12.5, Home: Cocoon Nebula - Struggling against the approaching twilight and distant porch light. Think I got it for the second time, only other time was in a 4" Vixen f/10 achromat with binoviewer. Jumped from 81 Cyg south to sharply defined B168. Followed the dark nebula east to the spot. Amorphous mass on the edge of visibility, easiest feature to see were dark rifts which helped define edges. Responded slightly to H-Beta filter. Primarily used 31 Nagler. Need to familiarize myself better with the field before trying more magnification. Cluster Cr470 not evident.
- Sh 2-88, Vulpecula, Jun 20, 2011, Star12, Home: Not easily seen. Responds somewhat to O-III, best with UHC. No response to H-Beta. Indefinite edges, best view with 24 Brandon (42x) or 22 Panoptic (46x).
- IC 1318, Cygnus, Jun 9, 2011, Star12, Home: I did not see the double star but the Gamma Cyg region is incredible in the 48 Brandon (21x). A rich star field with hints of nebulosity. Adding a UHC filter makes a dramatic difference. (Hydrogen-Beta filter not effective.) The immediate impression is not that the nebulosity pops, but that prominent dark lanes are created running E-W and N of Gamma. As the eye acclimates the nebulosity becomes easier to trace, especially W and N of Gamma. Several weak open clusters embedded/associated with the area. I could spend hours on this star field. Identified IC 1318 a, c, d, and e.
- Sh 2-105, Cygnus, Jun 11, 2011, Star12, Home: NGC 6888. Reacts well to UHC filter, negative to H-Beta and O-III. Held steadily in 24 Brandon no filters (42x). Best view in 12 Brandon and 13 Ethos, SW portion of nebula most visible. Not sharply defined.