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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4622
Loc: Illinois, US
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Quote:
Ok, this one's name is kind of a misnomer. It is narrower than a broadband "LPR" filter and broader than a narrow-band "nebula" filter ("UHC-like"), so it is a jack of all trades but master of none. It will dim things more than the standard broadband LPR filters do, but will not provide quite the contrast improvement that narrower filters do on nebulae. The following article on filters might help a bit in understanding what is going on:
Actually, maybe I should consider getting one; it sounds kind of nice. 
Chris
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"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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Midnight Dan
professor emeritus
Reged: 01/23/08
Posts: 554
Loc: Brockport, NY
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Protheus:
I was thinking the same thing 
I kind of look at these kinds of filters as being different "strengths" of effect (although I know it's not quite that simple). Depending on your situation and what you're looking at you can pick a weaker one or a stronger one.
LPR (Broadband) - weak effect, bright images. Just cuts out a small band of sodium vapor light color, leaves the rest mostly alone. Can improve LP problems, but only mildly.
LPR/UHC (Bandpass) - medium effect, dimmer images. Allows light through in certain bands, but wider than UHC. Overall light pollution is reduced somewhat, Nebulae have some improvement in contrast.
UHC (Narrow Band) - strong effect, dim images. Allows only narrow area around Ha and OIII, but some also allow Hb and SII band. Sky and most objects dimmed significantly, leaving nebulae to stand out more distinctly.
OIII (Narrow band) - strongest effect, darker images. Allows very narrow band only around OIII. Only certain Nebulae with this kind of light will benefit.
As you go from weaker to stronger, the images get dimmer, contrast on some objects are improved more, but fewer objects will benefit. But it would be nice to have a range of these so you could ramp through them to find the best one for your situation and object of interest.
I currently have the Baader Moon & Skyglow and the Astronomik UHC. The Moon & Skyglow has a very mild effect on LP but is good for general observing. The UHC is great for nebulae, but is too strong for general observing. At some point I may think about the Baader UHC-S as an in-between.
-Dan
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Scopes: Celestron NexStar 8, Orion EON 72mm ED/APO on Astroview mount (EQ3)
Eyepieces: Celestron 40mm, 25mm, Baader Hyperion 13mm, 8mm, 5mm
Other: Telrad, 2x Barlow, 0.63x Focal Reducer, Dew-not strips, DewBuster controller
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4622
Loc: Illinois, US
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Quote:
UHC (Narrow Band) - strong effect, dim images. Allows only narrow area around Ha and OIII, but some also allow Hb and SII band. Sky and most objects dimmed significantly, leaving nebulae to stand out more distinctly.
OIII (Narrow band) - strongest effect, darker images. Allows very narrow band only around OIII. Only certain Nebulae with this kind of light will benefit.
Sure, but actually here, you can think of UHC as admitting multiple various narrow bands vs. the OIII's single narrow band...
Chris
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"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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coutleef
scholastic sledgehammer
Reged: 02/21/08
Posts: 806
Loc: Montreal and St-Donat, Québec,...
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I just bougth the astronomik UHC-E that also looks like an internediary between the UHC and LPR filters.
I'll keep you posted on the benefits of this one, although i do now own any other to see a difference
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François
Nexstar 8 SE
50mm StellarVue finderscope, Astronomik UHC-E and Orion OIII filters
WO Swan 40mm; TV Pan 22mm; TV Nagler 9T6, 12T4, 17T4; TV Plossl 11mm and 15mm.
WO 2" dielectric diagonal retrofitted with Denk Power Switch (and now reach the zenith with the shorty adapter).
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 6754
Loc: Beatrice, Nebraska
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Quote:
Quote:
Ok, this one's name is kind of a misnomer. It is narrower than a broadband "LPR" filter and broader than a narrow-band "nebula" filter ("UHC-like"), so it is a jack of all trades but master of none. It will dim things more than the standard broadband LPR filters do, but will not provide quite the contrast improvement that narrower filters do on nebulae. The following article on filters might help a bit in understanding what is going on:
Actually, maybe I should consider getting one; it sounds kind of nice.
Chris
Nope, it isn't all that nice. On nebulae, it does not provide as much rejection of skyglow as the "true" narrowband filters. This is especially noticeable for HP Sodium emission, where that broad emission band in the yellow part of the spectrum ends up leaking into these "compromise" filters. I have a DGM Optics VHT ("Very High Transmission") filter, which is one of these compromise units. I was a little disappointed in how well it performed even under a dark sky. Yes, it helped on emission nebulae, but not as much as the "true" narrowband filters (Lumicon UHC, Orion Ultrablock). On continuum objects, it rejected a little *too much* light, resulting in fainter galaxies and reflection nebulosity when compared with the standard broadband filter (Lumicon Deep-sky). If I want to look at *stars*, I use a broadband filter or none at all. If I want to look at *nebulae*, I will use a narrow-band "nebula" filter or a line filter. I want to see the nebula and I couldn't care less how bright the stars are. The proper filter should be used for the right object, and to cover all bases, one really needs at a minimum a narrowband "UHC-like" filter and an Oxygen III line filter. Compromise here is a "lose-lose" situation, so if someone goes with such a filter, they should expect some compromise in performance. Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
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jloakland
member
Reged: 08/11/08
Posts: 13
Loc: Oakland, CA
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well, it was finally clear enough to give this a try on neblulae and it worked like a charm...turned M27 from a faint blob into a bow tie. looking forward to trying the OIII out sometime.
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