Author Topic: OIII or UHC Filter?  (Read 207 times)

Javier Gutierrez

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Re: OIII or UHC Filter?
« Reply #15 on: January 13, 2018, 06:36:53 AM »
Quote

Just to clarify, a "true UHC" filter passes O-III and H-Beta lines..

<p class="citation">Quote

If one wanted to pick up an OIII filter for an 8" scope with 1.25" EPs, what brand might be recommended?
[/quote]

Before buying a 1.25 inch filter, I suggest thinking carefully about whether you will ever want to use it with a 2 inch eyepiece. Filters are generally most effective at lower magnifications so if you have or will have 2 inch eyepieces, a 2 inch filter will save you money in the long run because it can be used with both 1.25 inch and 2 inch eyepieces if the focuser is a 2 inch.

Jon

Deandre Fulce

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Re: OIII or UHC Filter?
« Reply #16 on: January 13, 2018, 07:37:19 AM »
2" Orion OIII works well for me on the right targets. More affordable than the others which I have not had opportunity to compare against. I do get noticeable results with it so have not been in a rush to upgrade, which might not even be necessary.

Jeff Smith

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Re: OIII or UHC Filter?
« Reply #17 on: January 13, 2018, 12:49:09 PM »
I use the NPB for most nebula and a Celestron (same as Baader) OIII for the Veil nebula and some planetary. Most of the time it will be in low power eyepieces. For you, the 25mm would be your best choice. You may want to upgrade the 25mm basic plossl with something like a 24mm 68* or 82* SWA lens. The wider view is better with the filter. M42 would fill most of the FOV in these EP's.

kentifilitt

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Re: OIII or UHC Filter?
« Reply #18 on: January 14, 2018, 03:39:29 AM »
So which type would be best for M42?

Thanks

Kenneth Naim

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Re: OIII or UHC Filter?
« Reply #19 on: January 18, 2018, 12:16:16 AM »
Quote
So which type would be best for M42?

Thanks


It depends on what you want to see of it and what your local level of skyglow is. Under dark sky conditions, the narrow-band "UHC-like" filters (Lumicon UHC, DGM NPB, Orion Ultrablock, etc.) will usually show a somewhat larger area of nebulosity at a slightly higher brightness level than the true OIII line filters do.  However, the OIII will show the nebula with greater contrast and dark detail than the narrow-band filters like the Lumicon UHC do. Also, under slightly heavier skyglow, the OIII will provide a bit better rejection of that skyglow than the narrow-band nebula filters do, although again, both these filter types tend to perform best under skies that are already fairly dark. Under significant skyglow, you will need to shield your observing location from local lighting and take extra precautions to get fully dark adapted and shield your eyes and the telescope's eyepiece from any ambient lighting (observing hoods, etc.). Most of the time, I like using a narrow-band nebula filter like my DGM Optics NPB rather than using the OIII on M42, but there are times when I do switch back to my Lumicon OIII to get that extra boost in contrast. For this reason, I often recommend getting both a good narrow-band nebula filter *and* a good Oxygen III (OIII) line filter to sort of "cover all the bases". If you would like to know which filter may work better with which object, the following article may be of some use:

FILTER PERFORMANCE COMPARISONS FOR SOME COMMON NEBULAE
http://www.prairieas...common-nebulae/

Clear skies to you.

Richard Reed

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Re: OIII or UHC Filter?
« Reply #20 on: January 20, 2018, 08:05:43 PM »
Generally, for M42:
--to see stars and nebula---no filter
--to see more nebula and slightly suppressed stars---a broadband filter
--to see more nebula extent with darker sky background and more suppressed stars---a narrowband filter
--to see small details in particular places in the nebula, but with overall less nebula visible---an O-III line filter

The best bet? A narrowband (i.e.UHC type) filter.

Milan Gainer

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Re: OIII or UHC Filter?
« Reply #21 on: January 22, 2018, 10:39:44 PM »
Hi
See the link a couple posts up to Dave Mitsky's review. Scrolldown to M42.
Fortunately that ones pretty no matter what.

adlamontma

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Re: OIII or UHC Filter?
« Reply #22 on: January 23, 2018, 11:08:53 AM »
Woops, hadn't refreshed my browser and there had been other responses to your ? Dartguy.

Lauro Mason

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Re: OIII or UHC Filter?
« Reply #23 on: January 25, 2018, 12:18:35 PM »
Quote
Generally, for M42:
--to see stars and nebula---no filter
--to see more nebula and slightly suppressed stars---a broadband filter
--to see more nebula extent with darker sky background and more suppressed stars---a narrowband filter
--to see small details in particular places in the nebula, but with overall less nebula visible---an O-III line filter

The best bet? A narrowband (i.e.UHC type) filter.


Agree! Best to look for E and F stars in Trapezium inside M42 would be without a filter!

genssizafa

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Re: OIII or UHC Filter?
« Reply #24 on: January 25, 2018, 04:57:55 PM »
Quote
Generally, for M42:
--to see stars and nebula---no filter
--to see more nebula and slightly suppressed stars---a broadband filter
--to see more nebula extent with darker sky background and more suppressed stars---a narrowband filter
--to see small details in particular places in the nebula, but with overall less nebula visible---an O-III line filter

The best bet? A narrowband (i.e.UHC type) filter.


I prefer a broadband filter for M42 with my small scopes.

Jorge Herbert

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Re: OIII or UHC Filter?
« Reply #25 on: January 31, 2018, 03:32:59 AM »
Quote
Quote

Generally, for M42:
--to see stars and nebula---no filter
--to see more nebula and slightly suppressed stars---a broadband filter
--to see more nebula extent with darker sky background and more suppressed stars---a narrowband filter
--to see small details in particular places in the nebula, but with overall less nebula visible---an O-III line filter

The best bet? A narrowband (i.e.UHC type) filter.


I prefer a broadband filter for M42 with my small scopes.

In my 100mm f/6 refractor, I prefer the narrow-band nebula filters on M42 over the broad-band ones. M42 looks somewhat larger with a bit more contrast and shows the large southern "loop" better. Clear skies to you.

Marlin Riewer

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Re: OIII or UHC Filter?
« Reply #26 on: February 02, 2018, 05:57:26 PM »
If you have one you should try an H-Beta filter on M42 just to see the variety it brings - different areas brightly highlighted. Not recommended that you go out and pick up an H-Beta to use on M42 but it's interesting how this powerful broad spectrum emitter lights up through any of our common visual filters.

Gary Allen

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Re: OIII or UHC Filter?
« Reply #27 on: February 02, 2018, 08:40:36 PM »
Quote
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.


I agree. Most people who say O-III filters aren't "too dark' are using scopes 10 inches or larger.

Darren Hatch

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Re: OIII or UHC Filter?
« Reply #28 on: February 04, 2018, 01:31:42 PM »
My first use of an O-III filter was with a 4" SCT on the Veil Nebula, and it worked great.
Since then, I've used it in a 2" finder scope and it worked fine there, too, revealing the entire Veil in one field.

The purpose of a nebula filter is to reveal the nebula. NGC7293 (The Helix Nebula), for instance, is very faint in my 4" refractor
unless I use an O-III filter, which use makes the nebula really stand out.
Stars disappear, as does background light in the field. But the nebula really pops out.
The overall image of the entire field is darker, sure. But the nebula is WAY easier to see and even see details in.

One thing has recently happened that might be of interest:
There are now some wider bandwidth O-III filters out there, from StarGuy, Explore Scientific, and Optolong.
They don't dim the stars or field as much.
Sure, the ultimate contrast is lower, but they're still WAY better than no filter at all.
Maybe the intention is to address the smaller scope (&lt;8") market.

Mark Dominguez

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Re: OIII or UHC Filter?
« Reply #29 on: February 09, 2018, 09:15:39 AM »
Quote
Quote

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.


I agree. Most people who say O-III filters aren't "too dark' are using scopes 10 inches or larger.
No most people who say this know exactly how to use an OIII filter in a smaller scope. One of my favorite views of the North American Nebula is in my 100mm f/6 refractor at 15x and 25x using the Lumicon OIII filter. You have to use the right power range, get fully dark adapted, and use averted vision, but an OIII filter can be effectively used in apertures smaller than eight inches. Clear skies to you.