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UHC or OIII filter?

tombulgin

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Nosivad

Nosivad

Posted
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I noticed what appeared to be two different types of Baader nebula filter:

Baader UHC-S / L-Booster-Filter 1'/4 optically polished [baa-42-2458275] - 49.00 : 365Astronomy: Discovery for every day!

Baader UHC-S Nebula Filter (1.25") 31.7mm

Are these actually the same filter, just listed with different names?

Thanks

Tb

Yes they are the same according to the reference number given on each advert. BTW I have just ordered the 1.25" version from 365astronomy as a prezzie but probably won't be able to use it til after the 25th! It's a case of price versus usefulness and I think the UHC is a better allrounder.

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RikM

RikM

Posted
Posted

Got my OIII filter today. Opened the box and...it's scratched and has to go back :)

Three small dots in the coatings where you can see the light shining through if you hold it up to the light. Bummer :(

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acey

acey

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Posted
Got my OIII filter today. Opened the box and...it's scratched and has to go back :)

Three small dots in the coatings where you can see the light shining through if you hold it up to the light. Bummer :(

There was a recent post describing the same thing: small flaws in the coating of a filter. Sounds like quality control is one of the things to take into account when comparing different brands.

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John

John

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Posted
OK. I went and did it. Couldn't help myself from going higher-end (especially after your bad luck Rik)....Astronomik UHC 1.25" ordered. Please, nobody say it was a bad call!

tb

I have an Astronomik O-III 2" and it's performance is really excellent. I assume you won't be using 2" eyepieces then ?

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RikM

RikM

Posted
Posted
OK. I went and did it. Couldn't help myself from going higher-end (especially after your bad luck Rik)....Astronomik UHC 1.25" ordered. Please, nobody say it was a bad call!

tb

That is exactly what I have asked for as a replacement :( I would rather pay the extra for peace of mind.

Zoltan at 365Astronomy has been very good about it :)

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tombulgin

tombulgin

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I only have the 1.25" eyepieces currently (10mm and 25mm standard issue with Skyliner 10" dob), so my first filter is also 1.25".

My scope has a 2" EP adapter, but with funds being somewhat limited, i can't go and splash firstly on a 2" eyepiece, before then fitting out with all the 2" add-ons.

A365 says my order is "Preparing for dispatch".....come on!!

Tb

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rwilkey

rwilkey

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The Baader UHC-S let more light through so are better for smaller aperture scopes, as far as I have read, but not actually used one. The band pass is the important thing I think, I use the SW ones and have no complaints, can't afford Lumicron, but they have a good press hereabouts.

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John

John

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Posted

The filters being discussed here are used to enhance the contrast in nebulae. They will have an effect under both dark and moderately light polluted skies but the objects being viewed would look better under dark skies, as ever.

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Nosivad

Nosivad

Posted
Posted
Just to clarify for me, would a filter still be beneficial in dark sky areas or are they purely for controlling light pollution?

Hi, I have bought a UHC filter even though I do not have much light pollution here. I have not had a chance to use it yet(prezzie for Xmas) but from what I have read, it helps with light pollution but is a contrast filter for gaseous nebulae so I think it's a good investment.

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rwilkey

rwilkey

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Hi, most filters are good in light-polluted areas, but the UHC and OIII filters not specifically so, they just let through the narrow bands of light associated with nebula (O (x2), Hb etc), so in effect exclude all other forms of light transmission.

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Space Bat

Space Bat

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The UHC is a very good all round filter - and will enhance most objects and well worth the money....

The O3 is a narrow bandpass filter and excels in viewing certain objects such as planetary nebulae and feint diffuse nebulae - excellent for picking out the veil for example.

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acey

acey

Posted
Posted
Just to clarify for me, would a filter still be beneficial in dark sky areas or are they purely for controlling light pollution?

Emission nebulae (e.g. Orion Nebula M42, Ring Nebula M57, Crab Nebula M1, Veil) emit most of their light at particular frequencies, rather than having a continuous "white" spectrum like stars or galaxies. "Nebula filters" (UHC, OIII etc) transmit only those special frequencies, thereby enhancing contrast by making the background sky darker. A nebula filter will work in light-polluted or dark-sky conditions, but only on emission nebulae. Its effect on any other kind of DSO (cluster, galaxy, reflection nebula, star) is just to make it darker and harder to see.

The first "light pollution filters" worked by blocking particular frequencies emitted by sodium vapour: i.e. the orange glow of low-pressure sodium streetlights. More modern high-pressure sodium lights emit a far whiter light, and light pollution from other sources tends to be white. Under those conditions, you can't separate white man-made light from white galaxy light, so a "light pollution filter" is, strictly speaking, impossible. But some people claim they still give some beneift, maybe because their area still has predominantly low-pressure sodium lighting, or because there is some other effect at work that enhances perception. Personally I've never tried them - I just drive to a dark site.

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michael.h.f.wilkinson

michael.h.f.wilkinson

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I have tried wide-band LPR filters, and they still have limited use in suburban areas, first of al because low-pressure-sodium light is still in use, secondly because mercury lighting is also filtered out to a great extent, and last of all, because even high-pressure-sodium light still has a lot of line emission. LPR filters can help a bit on galaxies.

To illustrate Acey's point, I used my UHC filter in France from a very dark site to enhance both the Veil, the North America Nebula, and the Pelican. The former two were visible without UHC, but much clearer with, and the latter was only visible with UHC filter.

Even in the darkest possible areas on Earth there is such a thing as sky-glow. Sky-glow is caused by photochemical reactions at night when molecules excited by UV radiation by day react back into a stable state under emission of light (a sort of very low level phosphorescence in the sky). This is also removed by the UHC filter. Reduction of starlight and the milky-way background also helps.

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  • 2 years later...
Charic

Charic

Posted
Posted
A 10" will do fine with an O III filter, although just remember the O III is O III specific!

A UHC covers 3 lines including O III so I would say the UHC offers a wider option for your money. 

Remember you need enough photons to capture nebulosity so the darker the sky and larger the aperture the better.

I would also consider the filter size. For me I only have one 2" EP, and would probably only want to use the Panaview with a nebulae filter. I know higher magnification enhances contrast ect, but I would want the maximum amount of light throughput, so using an 8" telescope and a larger focal length EP should do the trick.

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LukeSkywatcher

LukeSkywatcher

Posted
Posted

It would be better to get yourself a UHC filter as the range of objects it improves upon is far greater then an OIII filter. When i was trying to decide which to get (UHC or OIII), someone said to me something which has stuck in my head ever since and i always say it to others in the same situation:

"A UHC filter will make the already visible to the naked eye, more visible (M42 etc) and an OIII will make the invisible to the naked eye,visible (Veil nebula,Rosette etc)".

Never truer words spoken because i ended up buying one of each and they perform exactly like the above words of wisdom which i was told. 

Given a choice between both, if you could only have one or the other, A UHC is a better choice.

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Dave In Vermont

Dave In Vermont

Posted
Posted

While your advice is sound, some might have a cause to pause regards your making suggestions to a grave-yard. You are addressing the "Ghosts of Nebulae Past."

If you note the date on the last poster's reply - before you, Charic - it went up on December 14th, 2011. :grin::eek:

Must have been a great night at the eyepiece!

Clear Skies,

Dave

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