O-III Filters For Visual Observing...

[John]

I was going to suggest the Castell O-III as a lower cost alternative that gives you a good dose of the "O-III experience". Mark has mentioned it above already !

 

[Captain Scarlet]

I’ve discovered my astronomic oiii fits and sits quite neatly inside the detachable eye cup of my 10x50 bins.

There may even be some gaps in clouds tonight so Cygnus and the Veil beckons!

 

[steveex2003]

For whatever its worth I recently bought a cheap (<£30 a pop) SVbony Olll and UHC filter, just really to have a play with. I found that I needed aperture for the Olll. In smaller scopes it was just too dark. With the UHC I could see structure in M16 (Bortle 5) that simply wasn't there without it in an 80mm frac. 

[Stardaze]

There was a lot of talk about filters on a recent thread and clearly the higher priced filters have tighter band widths, the cheaper variants are a little looser, given the lesser process, so it's a lottery as to how good they are. I decided to buy a secondhand Astonomik O-III as I desperately wanted to see the Veil too. Whilst they are expensive, I knew I'd end up buying a premium version at some point and I also didn't want to blame my kit if I failed to see what I was seeking so bit the bullet. The TeleVue Nebula UHC is on the list in time for Orion this year..

[Stu]

1 hour ago, steveex2003 said:

For whatever its worth I recently bought a cheap (<£30 a pop) SVbony Olll and UHC filter, just really to have a play with. I found that I needed aperture for the Olll. In smaller scopes it was just too dark. With the UHC I could see structure in M16 (Bortle 5) that simply wasn't there without it in an 80mm frac. 

A lot depends on the filter’s levels of transmission, your dark adaptation and also the skies you are observing under. These last too often go hand in hand of course; it can be tricky to get dark adapted with light pollution so an observing hood can really help in these cases.

When I was down in Pembrokeshire last year the skies were Mag 21 ish with an SQM, Bortle 4 according to Wikipedia. I used my Lumicon OIII quite successfully in my 72mm refractor to see the Veil very clearly, so whilst aperture is helpful, for widefield views a smaller frac can work very well indeed.

[markse68]

My oiii is an astronomik imaging one- do you suppose that could have a negative impact on its use visually? I can’t remember which bandwidth version it is- maybe the 6nm. The imaging version maybe doesn’t have quite as high transmission. I know it’s my sky that’s preventing me see  the veil- one day i’ll get the timing right and have my mind blown i’m sure

[Waldemar]

On the outside edge of the filter casing, the filtertype and bandwith is mentioned. The difference between the visual and imaging filter is an extra UV and IR coating. Will be no problem.
Just try and you will know from experience...

Edited August 26, 2020 by Waldemar

[Rob_UK_SE]

25 minutes ago, markse68 said:

My oiii is an astronomik imaging one- do you suppose that could have a negative impact on its use visually? I can’t remember which bandwidth version it is- maybe the 6nm. The imaging version maybe doesn’t have quite as high transmission. I know it’s my sky that’s preventing me see  the veil- one day i’ll get the timing right and have my mind blown i’m sure

If you have the 6nm OIII-CCD version, your filter really targets the 501nm OIII line, but not the 496nm part. It is much more narrow/aggressive and therefore less suited to visual observation.

 

Edited August 26, 2020 by Rob_UK_SE

[markse68]

1 hour ago, Rob_UK_SE said:

If you have the 6nm OIII-CCD version, your filter really targets the 501nm OIII line, but not the 496nm part. It is much more narrow/aggressive and therefore less suited to visual observation.

 

if it’s the 12 though it should work ok?

[Rob_UK_SE]

The two CCD-specific ones concentrate on 95%+ of the 501nm line region, but the 6mn (being tighter) doesn’t provide anywhere near the same % transmission of the 496nm part.  Their respective differences are more about suitability for the camera/sensor being used and the focal ratio of the telescope. They both work well for imaging as, in addition to improved contrast around OIII regions, they also provide a solution to some of the many challenges created by light pollution (the 6nm filter, in particular). I assume that the 6nm one simply requires longer exposure times? I have not personally used a CCD-specific filter to observe visually, but I would also assume OIII observations are still achievable. However, the view would be dimmer, when using the 6nm version, due to the reduced OIII bandwidth. The 12nm version should be similar to the visual one which, unlike your CCD version, doesn’t contain the added IR-blocker as it is not required.

The highly praised visual OIII filters provide 95%+ of both 496nm and 501nm OIII lines.

Below is the 12nm CCD OIII filter:
 

Edited August 26, 2020 by Rob_UK_SE

[RT65CB-SWL]

On 24/08/2020 at 18:31, merlin100 said:

I read that O-III filters can help with certain nebulae whilst visually observing.  What type and price should I be looking at and do have you any recommendations?

 

On 24/08/2020 at 20:33, callisto said:

So correct me if I'm wrong.......The advice would be to spend more on the Astronomik/Lumicon filters etc, and stay away from the likes of the OVL/SW ones?

I, myself try to keep within a budget of optional add-ons. After I read the reviews of OVL/SW UHC & O-lll on the FLO page, and elsewhere, I purchased the Explore Scientific ones. Though the ES may not be in the same league as Astronomik/Lumicon, the reviews were better than OVL/SW.

Another useful filter is the the Baader Planetarium Neodymium. I think of it as 'the Swiss-army knife' filter for visual observing. 

[Mark at Beaufort]

2 hours ago, Philip R said:

Another useful filter is the the Baader Planetarium Neodymium. I think of it as 'the Swiss-army knife' filter for visual observing. 

I agree Philip - Never tried the Explore Scientific brand of filters but I am sure they work perfectly okay.

Just checked and the UHC has a 48nm bandwidth and the O-III is 28nm.

This is an interesting list

2016 Nebula Filter Buyers Guide(1).xlsx

[jetstream]

My highly recommended Orion Ultrablock earned the nickname Ultra JUNK... worst filter ever. I threw it out.

With filters other than the former Lumicon, current Astronomik and the new Televue the issue is huge sample to sample variation IMHO. Totally a crap shoot- actually craps has better odds than getting a good off brand filter IMHO.

[John]

3 hours ago, jetstream said:

My highly recommended Orion Ultrablock earned the nickname Ultra JUNK... worst filter ever. I threw it out.

With filters other than the former Lumicon, current Astronomik and the new Televue the issue is huge sample to sample variation IMHO. Totally a crap shoot- actually craps has better odds than getting a good off brand filter IMHO.

The Orion Ultrablock is a fine example of the crap shoot you mention. I've seen tests showing large variations in pass rate and width. Some are decent, some are pretty much useless.

I had one years back which was OK. A more recent one I tried didn't seem to do much at all

 

[Colossal Plossl]

Apologies to hijack the thread but I have also been interested in filters.  The Astronomik UHC or cheaper UHC-E or the TV one (made by Astronomik).

Was considering the UHC-E which according to Astronomik is better suited for smaller scopes up to 127mm.   Mine is 130mm so not sure if that would make a difference

A lot have people have been saying get the best quality ones as numerous cheaper ones can end up to the same cost as Astronomik/Lumicon ones?

I'm interested in nebula and galaxies (not sure if these filters have any effect on Galaxies?)

 

Skywatcher 130P flexitube (F5)

650 focal length

130mm aperture

 

Bortle 6

 

Edit: Forgot to mention this is purely for visual observing.  Not imaging.

Edited August 26, 2020 by Colossal Plossl

[Stu]

11 minutes ago, Colossal Plossl said:

Apologies to hijack the thread but I have also been interested in filters.  The Astronomik UHC or cheaper UHC-E or the TV one (made by Astronomik).

Was considering the UHC-E which according to Astronomik is better suited for smaller scopes up to 127mm.   Mine is 130mm so not sure if that would make a difference

A lot have people have been saying get the best quality ones as numerous cheaper ones can end up to the same cost as Astronomik/Lumicon ones?

I'm interested in nebula and galaxies (not sure if these filters have any effect on Galaxies?)

 

Skywatcher 130P flexitube (F5)

650 focal length

130mm aperture

 

Edit: Forgot to mention this is purely for visual observing.  Not imaging.

I used my Lumicon OIII in my Heritage 150p very successfully the other night from home, and have used it in scopes down to a 72mm refractor particularly under a dark sky. I have a Heritage 130p so could try it in that, but my suggestion would be to get the full on UHC not the UHC-E, I think it will show better results.

[John]

These filters only improve the views of nebula. For galaxies, find the darkest skies you can.

With a 130mm I would go for the full UHC rather than the UHC-E. I use "full" O-III and UHC filters with 100mm apertures to good effect.

Looks like @Stu agrees with me 😀

 

[Colossal Plossl]

4 minutes ago, John said:

These filters only improve the views of nebula. For galaxies, find the darkest skies you can.

With a 130mm I would go for the full UHC rather than the UHC-E. I use "full" O-III and UHC filters with 100mm apertures to good effect.

Looks like @Stu agrees with me 😀

 

Thanks both.  Think i am struggling to understand (being a newb) the difference between O-III and UHC.  Also wondering if the Astronomik UHC and TV Bandmate are the same thing albeit higher premium for TV name etc?

I have not seen any Nebula.  Only galaxy I have seen is Andromeda, which looked cool, but LP was probably affecting my view so the filter(s) may help with this?

[John]

Filters won't really make much difference if you have lots of LP.

I have only used the Astronomik O-III filters, not the ones that they are now making for Tele Vue but the latter are getting excellent feedback from experienced observers. Worth the price difference ? - your call I guess !

Here is a good piece on the deep sky type filters:

https://astronomy.com/-/media/import/files/pdf/8/c/7/0805_nebula_filters.pdf

 

[Stu]

20 minutes ago, John said:

Filters won't really make much difference if you have lots of LP.

I have only used the Astronomik O-III filters, not the ones that they are now making for Tele Vue but the latter are getting excellent feedback from experienced observers. Worth the price difference ? - your call I guess !

Here is a good piece on the deep sky type filters:

https://astronomy.com/-/media/import/files/pdf/8/c/7/0805_nebula_filters.pdf

 

Regarding the first comment my skies vary between Mag 4.5 and 5 NELM. You may have seen comments I made saying I had good views of the Veil the other night using the Lumicon OIII in my Heritage 150p when the skies were Mag 5 NELM with good transparency. It probably would have been visible at Mag 4.5 NELM but much more challenging I’m sure and with less detail/contrast. Dark adaptation helps a lot too, so an observing hood is useful when in light polluted conditions. The overall brightness of the view is dimmed with a filter, but the contrast is increased.

John’s link is a good one, this is another often posted link for information on which filters work well for a range of different objects.

https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/

This one may have been posted already but useful to repeat I think.

http://www.astrosurf.com/buil/filters/curves.htm

Broadly, the UHC includes the Hb line plus the two OIII lines, the OIII filter just passes the two OIII lines, so the OIII is the narrower/more aggressive of the two. They do vary quite a lot though as you can see from the graphs in the last link.

[John]

8 minutes ago, Stu said:

Regarding the first comment my skies vary between Mag 4.5 and 5 NELM. You may have seen comments I made saying I had good views of the Veil the other night using the Lumicon OIII in my Heritage 150p when the skies were Mag 5 NELM with good transparency. It probably would have been visible at Mag 4.5 NELM but much more challenging I’m sure and with less detail/contrast. Dark adaptation helps a lot too, so an observing hood is useful when in light polluted conditions. The overall brightness of the view is dimmed with a filter, but the contrast is increased....

 

Quite right Stu - such filters do help with nebulae under LP skies - in some cases at least you see something !

My post should have made it clearer that galaxies won't benefit in response to @Colossal Plossl's comment on the visibility of the Andromeda galaxy.

 

 

[Stu]

8 hours ago, John said:

My post should have made it clearer that galaxies won't benefit in response to @Colossal Plossl's comment on the visibility of the Andromeda galaxy.

Ah yes, missed that bit! 🤣

Galaxies need dark skies as you say, but filters, particularly the more narrowband ones will show a real difference on emission nebulae even with LP. I think glare is quite a big problem (as opposed to light pollution) by which I mean directly visible lights rather than the visible sky glow. Glare really stops you getting any level of dark adaptation so can make narrowband filters less effective, hence the recommendation for an observing hood of some sort.

[John]

16 minutes ago, Stu said:

Ah yes, missed that bit! 🤣

Galaxies need dark skies as you say, but filters, particularly the more narrowband ones will show a real difference even with LP.....

With nebulae, but not with galaxies ?

I suspect that's what you mean though

[Stu]

8 hours ago, John said:

With nebulae, but not with galaxies ?

I suspect that's what you mean though

Not doing very well here am I John! Yes, with nebulae (specifically emission nebulae) not galaxies. I’ve edited my post to make this clearer, thanks 👍👍

[jetstream]

18 hours ago, Colossal Plossl said:

Only galaxy I have seen is Andromeda, which looked cool, but LP was probably affecting my view so the filter(s) may help with this?

Filters, any filters do not help in seeing galaxies, including my Baader Neodymium.