Author Topic: OIII or UHC Filter?  (Read 943 times)

Mohamed Wiest

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OIII or UHC Filter?
« on: December 24, 2017, 12:38:13 AM »
Hi Guys,

I'mnew to astronomy thus looking for a bit of advice.

I've got the" SkywactherDobsonian with the 10mm and 25mm EP's.  Ivebought a 2x barlow and celestonX-Cel LX 7mm.

I'm wanting to view nebulea in as much detail as I can with this setup and'm looking into a filter to enhance my view.

I keep reading about OIII and UHC filters.  Could anyone tell me which they believe would be better with my setup?

Thanks
Tom



tiodiacontti

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Re: OIII or UHC Filter?
« Reply #1 on: December 29, 2017, 04:30:39 AM »
Hi Tom,

Both of those filters will work very well with your setup. They are applicable to different objects. Nebular filters function by passing selected wavelengths of light through to your eye. The UHC (and UHC-type) and O-III filters pass a different set of wavelengths. Different nebulae emit different wavelengths of energy. Matching the passband of the filter to the emission spectrum of a nebula yields an effective combo for that object. Most observers end up with both filter types and then cover most objects effectively.

Many folks recommend the DGM NPB (UHC-type) filter as a good place to start for it's favorable cost/performance profile and effective performance on many nebulae. I agree. It is a lifetime filter that will not require upgrading. It is a narrowband filter. There are wideband UHC-type filters and they are less effective on nebular objects but have a broader range of smaller effects. I do not care for those. The Orion Ultrablock filter is another good narrowband UHC-type filter with a high cost/performance profile.

An O-III filter is a single passband filter (or as close to one as is used in visual astronomy) that selects an oxygen emission band that is common to lots of nebulae. It is very useful on, for example, many planetary nebulae. There are a few objects for which an O-III filter is often considered essential, generally older planetary nebulae that have expended much of their energy and expanded to become faintwispsfrom our vantage point.

Good luck with your selection. Again, both will work well with your gear. Nebular filters are often more effective used with larger exit pupils so you may want to try them with your 25mm ep at first. As you become more familiar with their effect, you will certainly want to give 'em a shot with whatever you have.

whoopsirode

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Re: OIII or UHC Filter?
« Reply #2 on: December 30, 2017, 08:26:08 PM »
Hi,

Thank you very much for this information. Have you had any experience of the Skywatcher filters? They both seem to get good reviews. As I am finding my feet in astronomy, I am going to start by looking at the easier to find items first (I've already mastered finding the moon haha). Plus, I live in between two large cities. If you were me, would you suggest starting with the Oiii or UHC?

Davione Boone

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Re: OIII or UHC Filter?
« Reply #3 on: December 31, 2017, 03:29:04 AM »
Tom,
I have no knowledge of the Skywatcher filters. I suspect that they are rebranded filters sourced from a filter manufacturer. There's nothing innately wrong with the practice. Lots of gear and many filters are outsourced and rebranded. Baader is a common source for filters. Baader makes some high performing and low performing filters so it depends on what the filter is. None of the Baader filters I am aware of perform as well as the DGM NPB, Orion Ultrablock or Lumicon UHC on objects for which a UHC filter is effective.

I can tell you I originally bought Orion UHC-type filters (probably Baader rebrands) as they were much less $$ and later had an opportunity to use a good narrowband UHC filter. Then I replaced the Orion as it just didn't measure up. If you can swing the DGM filter, you'll not likely ever become dissatisfied with it.

I referred several times to UHC-type filters. Lumicon makes the UHC filter. Others with like passbands are correctly called UHC-type filters. The Lumicon has become very expensive but is very good. The DMG is as good and slightly different but considerably less expensive. That's the one I recommend.

Somebody else may know the facts about the Skywatcher filters.

Dick Gentry

consmagestma

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Re: OIII or UHC Filter?
« Reply #4 on: January 03, 2018, 08:04:36 AM »
Hi Dick,

Thanks again for that advice. This forum is invaluable to me at the moment.

Kind Regards
Tom

asagnata

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Re: OIII or UHC Filter?
« Reply #5 on: January 04, 2018, 09:11:39 PM »
O-III filters work best at low magnification less than 10x per inch of aperture. Your 25mm eyepiece at 48x or 6x per inch should be OK, but the view with your other eyepieces could be kind of dim. The Barlow will also reduce brightness. A UHC filter doesn't dim the view as much, so you could use it at a bit higher magnification on more different objects.

skelevchasul

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Re: OIII or UHC Filter?
« Reply #6 on: January 07, 2018, 10:48:32 PM »
I was told by some more experienced folks that UHC or like Orion Ultranlock are best for 8" aperture, OIII coming into better use at higher apertures.

ceicomfeara

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Re: OIII or UHC Filter?
« Reply #7 on: January 08, 2018, 12:45:41 AM »
Thanks for the info to both of you. I noticed on a site called first light optics that they suggest the Oiii only be used on scopes of 8" or higher. Think i'll order a UHC filter then, to play it safe

Nick Ellis

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Re: OIII or UHC Filter?
« Reply #8 on: January 10, 2018, 06:08:18 PM »
A UHC filter transmits the H-Beta (hydrogen) emission and the O-III (oxygen) emission.
Without knowing the emission wavelengths of a particular nebula, the UHC is a "universal" filter.

Some nebulae have very low levels of H-Beta emission but are strong in the O-III lines. Most of these are planetary nebulae.
By narrowing the bandwidth even more than the UHC, contrast is enhanced slightly more. There is no minimum
size of scope for this filter--I have used one on a 50mm finder.

But, a UHC should certainly be your first nebula filter.
The name "UHC", by the way, is a Lumicon original name. Technically, we should refer to these as "narrowband" filters.
Good names to look for:
Lumicon UHC
DGM NPB
Thousand Oaks LP-2
Orion Ultrablock
Meade 908N (long discontinued--only available used)Some UHC filters with wider bandwidths that will still work OK (in dark skies), but give less contrast enhancement than the ones above:
StarGuy UHC
Optolong UHC
Astronomik UHC
Explore Scientific UHC
TeleVue BandMate Nebustar

Some brands that are either too wide, or have other bandwidth problems:
Baader UHC-S
Celestron UHC
Zhumell UHC

Ones I have not seen reviewed and cannot answer about:
Denkmeier UHC
OPT UHC
SkyWatcher UHC (but since SkyWatcher and Celestron are both Synta Corp. trademarks, i suspect this might be a rebadged Baader UHC-S)

contiostetti

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Re: OIII or UHC Filter?
« Reply #9 on: January 11, 2018, 12:00:55 AM »
Quote
O-III filters work best at low magnification less than 10x per inch of aperture.



O-III filters can be very successfully used at extremely high and high magnifications, particularly on compact planetary nebulae. Such magnifications easily exceed 30x inch of aperture. Observing conditions usually determine usable magnification at these extremes but the filter never fails to be useful in the appropriate application.
An O-III filter is useful in scopes of any aperture, despite internet rumors to the contrary. Oddly, UHC filters seem to have not yet received such treatment.

chirafepes

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Re: OIII or UHC Filter?
« Reply #10 on: January 11, 2018, 07:21:30 AM »
I agree with Starman1 that the UHC is probably the more universal filter to start out with for nebulae. While I started with the O-III, which opened up a whole new world for me, if I'd known more about the UHC way back when, I might have gone the other way.

As it stands now, I have all of the "big three." The UHC, the O-III and the H-beta. I can experiment around and have the aperture to back it up. As for an 8-inch, you can't go wrong to start with a UHC, especially with the better technology of filters than when I started using them in the 80's.

Once you get going and want to expand your arsenal, then go for the O-III and finally the H-beta in that order. I say that because the O-III will bring out a lot more nebulae than the H-beta. The H-beta, though some say it's only good for the Horsehead and a few more dark nebulae, is actually good for quite a few more brighter nebulae to enhance certain features beyond what the others will do, such as the Orion, the Lagoon and the Triffid. However, with an 8-inch aperture, the results will be more subtle than what I get in mind, but don't think they'll be invisible.

Hope my additional blathering helps. Another great expert with filters is David Kinsley. I think he's tried almost every filter ever made, or close to it. Then again, Starman1 also knows his stuff!

Warren Tucker

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Re: OIII or UHC Filter?
« Reply #11 on: January 11, 2018, 01:07:39 PM »
If one wanted to pick up an OIII filter for an 8" scope with 1.25" EPs, what brand might be recommended?

Fred Lafever

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Re: OIII or UHC Filter?
« Reply #12 on: January 11, 2018, 02:13:18 PM »
My preference would be Lumicon but I'm not sure they're even still in business. Starman1 would know. Also, for all the nuances of brand names, he or David Knisley would be able to direct you.

Jorge Herbert

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Re: OIII or UHC Filter?
« Reply #13 on: January 11, 2018, 04:28:42 PM »
Here's a really great report on filters.

http://www.prairieas...common-nebulae/

luseatcidood

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Re: OIII or UHC Filter?
« Reply #14 on: January 12, 2018, 09:09:50 PM »
For O-III, I'd say the best bandwidths are found with: Andover, Lumicon, Orion.
A bit too wide: Astronomik, Thousand Oaks, TeleVue, Optolong, StarGuy, Explore Scientific. These will still work well, but have less desirable bandwidths and chosen wavelengths.
A bit too narrow: Baader, Celestron, Custom Scientific, Omega, Optec