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Skywatcher OIII filter.

GazOC

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riklaunim

riklaunim

Posted
Posted

It seems like SW filters are very similar to Baader filters:

SW Light Pollution Filter = Baader Neodinium

SW O-III = Baader O-III

SW UHC = Baader UHC-S

They probably are made in different factories but the available charts and images show like the do the same thing :)

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zhgutas

zhgutas

Posted
Posted

IIRC Baader UHC-S does allow Ha as well as OIII and Hb lines, and apparently passes tiny bit more OIII than the SW one.. As for the Ha - in this instance it is supposedly invisible to the human eye so should not have any impact on visual performance. UHC-S also cuts off less "non-nebular" lines, therefore, apparently making it "less aggressive"

Marius

EDIT: found a chart from my old thread here. AFAIK, the TS UHC is the same as SW UHC.

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Merlin66

Merlin66

Posted
Posted

No disrespect to anyone... but I honestly have a problem with some discussions on filters and their relative benefits and performance.

It's so easy to check and verify filters objectively, by using a spectroscope; what light they pass and which ones they block.

Visually we perceive more of the night light around the 550nm and our response drops off towards the red and blue ends of the spectrum. Nebulae are visible because of the emissions from the various gases. They emit in specific wavelengths. If these wavelengths are passed we see them, if not - they appear fainter.

With imaging, the problem is really matching the QE curve of the camera to the bandwidth of the various filters. For example a Ha 8/10/15nm filter will still pass all the available Ha light - only. So when background stars appear faint or non existant, guess what... that's because not all their light is emitted in Ha - there's not enough Ha to register. No surprise.

Testing a light pollution filter is so simple- just look through the filter at a nearby streetlamp or sky glow from surrounding lights. If the filter works, the glow will be suppressed. What other wavelengths it passes is obviously of interest- a quick view of a star field/ nebulae will show the transmission and bandwidths..

Sorry, I'll lie down now and take my pill...

Just my 2c

Ken

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Astro_Baby

Astro_Baby

Posted
Posted

I dont diagree with the science there Merlin but what we perceive with our eyeballs is often different. Peoples eyeballs react differently, age plays a part etc.

I tried to be objective about the filters. My own personal preference is not to use them much because for me they boost contrast but at the expense of detail.

Others may find it different. Last year at SSP some people preferred the Veil when seen through a UHC - I thought the filter made the view worse myself. Scientifically the speaking the filters passing or blocking the same wavelengths but its how people observe that makes a difference.

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Astro_Baby

Astro_Baby

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Dont worry Ken - I didnt see it as a dig at all - was just making the case that the science is sound but unfortunately theres nothing scientific about peoples eyeballs :)

A 14" Dob might give better results than my weedy 8" scope :D

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Merlin66

Merlin66

Posted
Posted

The very interesting bandwidth illustration they have shows the relative performance.

Remember if the nebula is ONLY emitting in OIII then any other light getting through is not coming from the nebula.....it comes from stars in the immediate area.

post-15261-133877451122_thumb.jpg

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Moonshane

Moonshane

Posted
Posted

that's what struck me about these as they seem to let a bit more 'general light ' in and therefore might be more suitable to smaller scopes and the less experienced among us as they will allow more ready recognition of what is close by the target? I suppose that light passing through is one thing though and optical clarity, sharpness and coating stability over time are another. Then again if these last a third of the time of say an Astronomik, and the image quality is as good, you are still quids in on a new one. I think I'll have a punt at the UHC one and report back in due course.

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Ogri

Ogri

Posted
Posted

Seems these are low price, because an Austrian guy is buying them direct (according to a Babelfish translation from an Austrian site anyway).

As I am a bit addicted to 'anything Nebula', and I am now getting desperate for any excuse to buy a 32mm Panaview (good old Veil Nebula gallops to the rescue here with the 'appallingly low' magnification of that 32mm in the ST120), and after looking at some very good UHC/OIII/Deepsky comparisons linked here on SGL . . . . . . . .

Pheeeeeeeew! I think I will get a Castell 2" UHC. I don't 'think' there are any 'bad' UHC's made (I haven't found any via internet searches), and I don't 'think' 365Astronomy would stock them if they were rubbish.

Well it isn't going to be a dire expense, and my eyes do need all the help they can get with lovely Nebula's, and I can use it with my other EP's until I can get the Panaview as well.

See how easy it is to lighten the old wallet? lol!

I'll let you know if it's any good (apparently as Ken infers, just hold it up to the view and see what improves via the naked eye - but to do that I have to actually have one in my grubby mitts).

Must admit, those comparison tests (linked by Karen I think?) swung me convincingly towards a UHC for the ST120, as they were done at a low light pollution site and seem pretty solid.

I've managed to get away with not buying any filters at all as yet, just by being careful with the 'bright stuff'. :D

eta: Now nobody go buying any telescopes for the next week or so, so that I can actually get out there and do some testing once it arrives . . . . .

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Ogri

Ogri

Posted
Posted

Well the 2" Castell UHC has arrived (fair play, good service, not used them before), and the quality of the coatings and finish looks fine. Comes with a lens cloth as well.

It looks rather similar to the Skywatcher.

With my outdoor night glasses on, which have a 66% amber tint, anti UV and anti glare coatings, and silver mirroring, and holding the filter up to look through, the blue of the sky looked much richer.

There's one of those horrid streetlamps up the road from dad, so I'll check that when it gets dark, and fit it to the 'scope if it's clear enough to do some viewing, and report back later.

So far so good.

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steve_bham

steve_bham

Posted
Posted
Well the 2" Castell UHC has arrived (fair play, good service, not used them before), and the quality of the coatings and finish looks fine. Comes with a lens cloth as well.

It looks rather similar to the Skywatcher.

With my outdoor night glasses on, which have a 66% amber tint, anti UV and anti glare coatings, and silver mirroring, and holding the filter up to look through, the blue of the sky looked much richer.

There's one of those horrid streetlamps up the road from dad, so I'll check that when it gets dark, and fit it to the 'scope if it's clear enough to do some viewing, and report back later.

So far so good.

Be great to hear how you get on with it :D

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LukeSkywatcher

LukeSkywatcher

Posted
Posted

It's so easy to check and verify filters objectively, by using a spectroscope; what light they pass and which ones they block.

Thats GREAT if you understand how spectroscopes and stuff work. Many people DONT (myself included).

You have to read between the lines and the context of the question asked. An experienced observer would know the ins and outs and would not ask the question. A newbie will ask this question and really does not want/need to be blinded by science.

It is a simple case of Yes or No.

Sorry for getting on my soapbox here but i often find that when a newbie asks questions they are bombarded with technical info by seasoned observers. Sure the info is great but to the average Joe Soap newbie.................it means nothing and is daunting.

I am one of those Joe Soaps but have a bit more of an understanding of things (but not much).

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LukeSkywatcher

LukeSkywatcher

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Testing a light pollution filter is so simple- just look through the filter at a nearby streetlamp or sky glow from surrounding lights. If the filter works, the glow will be suppressed.

That was my road test of the cheapest LPF that FLO sell. I simply pointed it at a horrible orange streetlight across the road from me and looked through it (no scope involved). The orange glow from the light became invisible and i could see the bulb of the light as pure white light.

I have observed westwards directly between 2 of these streetlights with the SWLPF with no problem whatso ever. The sky is black and the stars etc are bright.

Sorry Merlin i am not/was not singling you out. Just making a general statement.

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Ogri

Ogri

Posted
Posted

The street light just came on and is now up to full output (not dark yet though), and it's terrific on that looking through it out of the telescope. There's just a very small dull red glow off the bulb itself.

Tilted at say a 45 deg angle, the view is very violet, straight on, it's a quite pleasant pale green sort of tint to it (if that's any help to 'those that know'). eta: Forgot to say it's got that 'mirrored look' too.

Looks like there's some decent gaps in the high altitude cloud for later . . . .

By the way perhaps worth noting, that in very good light, green is the best for contrast (my daytime glasses have a dark green tint for that reason). In bad light, amber is best (night driving glasses usually have around a 33% amber, but due to my pupils, I need a 66% amber so that's what my night glasses have, to compensate for the fixed pupil dilation) . So the 'pale green' aspect of the tint for the contrast, ticks the right boxes for me.

The best mirroring for day use by a mile, is blue mirroring, silver mirroring may just have the edge for night use (more complementary to the amber tint perhaps?), but there's not an awful lot in it. It looks like the filter has silver mirroring (so ok either way - to check it I'd need to photograph it in bright sunlight, as the underlying can then come through ok).

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Ogri

Ogri

Posted
Posted

Well viewing here was pretty dire tonight, but things were picking up a little as I was about to pack up, and I managed to pick out M29. So I quit while I was ahead. lol!

I'd tried for ages to get views around M16 and M17, but nothing that way was playing ball at all, sad to say.

I do like the contrast with this UHC used with the 1.25" 20mm SWA Erfle type EP at 30 x mag (given the conditions I didn't even bother trying any other eyepiece). I did a bit of viewing with and without it (though to be fair it was diving in where there was a chance of a view as much as anything), and with improved viewing conditions I think it'll be extremely useful to have this UHC available.

It might seem daft but it made it a lot easier to get focus with the standard untouched Synta R&P focuser too.

It seems to do what it says on the tin, so to speak, and I look forward to some viewing conditions when I can give it a good run on some nebula.

Put it this way, it's encouraged me to think about getting the 'milder' LP filter for viewing conditions like tonight, just for the choice of contrasts between them. I think it would be quite complementary and useful (especially with my eyes) to have it there to switch with the UHC.

So thanks for mentioning them, I doubt I would have taken the plunge with them for quite a while otherwise (I still haven't got the much needed polarising filters sorted yet, lol! But then I've been avoiding the bright stuff like crazy).

As I get more used to it, and have the chance to use it in better conditions, I'll perhaps do an update.

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  • 2 weeks later...
Ogri

Ogri

Posted
Posted

Nah viewing down here is really the pits at the moment. Lovely day yesterday, perfectly clear, then just as it was getting dark, vast swathes of cloud rush in. :D

Pretty much the same again tonight too. /sigh

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