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Equipment Discussions >> Eyepieces

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rick-SeMI
sage


Reged: 01/08/11

Loc: Michigan - USA
OIII Filter Choice
      #5432485 - 09/21/12 11:00 AM

Does anyone know of a site that shows the spectrum (wavelength) in nm that is allowed for the different OIII filters ?
Right now my choice for OIII is either the Baader, Lumicon or Orion 1.25 inch filters.

M97 the Owl Nebula is the target with an Orion XT10i.
Which OIII filter would be best suited for this one?

I figure if it is good for M97, it should be pretty good for the other nebula's ?

Thanks


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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: OIII Filter Choice new [Re: rick-SeMI]
      #5432514 - 09/21/12 11:19 AM

There are many websites that show test results for particular filters, but in the case of your 3 choices, from wide at the top of the list to narrow at the bottom, they are:
Orion (about 15nm, IIRC)
Lumicon (about 12nm)
Baader (about 8.5nm)

The Baader "clips" the 496nm O-III line at about 50% transmission, but since the primary emission in the O-III lines is at 501nm, that doesn't seem to hurt that much.
Frankly, all 3 filters are good, so you won't lose with any of them.
But the Baader will likely give the maximum contrast.

In a small scope, the extremely narrow bandwidth will darken the sky and stars and make the field perhaps unaesthetically dark.
Sometimes there is a reason for a slightly wider bandwidth.
Not only do we want an enhanced nebula image--sometimes the "context" is important, too.


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Ernest_SPB
sage


Reged: 11/13/10

Loc: St.-Petersburg, Russia
Re: OIII Filter Choice new [Re: Starman1]
      #5432545 - 09/21/12 11:40 AM

I find Baader OIII too much dark for visual application.

It looks cutting some quote of useful light from OIII objects. I had possibility to compare it with Lumicon and saw that the last produced brighter and more contrast image over the most OIII nebulae.

OIII from Baader is preferred by my collegue who deal with astronomical photography.


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: OIII Filter Choice new [Re: Ernest_SPB]
      #5432647 - 09/21/12 12:43 PM Attachment (27 downloads)

Quote:

I find Baader OIII too much dark for visual application.

It looks cutting some quote of useful light from OIII objects. I had possibility to compare it with Lumicon and saw that the last produced brighter and more contrast image over the most OIII nebulae.

OIII from Baader is preferred by my collegue who deal with astronomical photography.




The Baader O-III works extremely good on the Veil and other targets. I own the Celestron which is the Baader re-branded. The Lumicon indeed has a wider bandpass as I did a test with a friend in a dark sky situation, and I found the Lumicon slightly better on M-17 and a few other targets. However, I see no point in selling off my Celestron / Baader O-III for a touch wider bandpass.

The Baader O-III would be a good choice if you're on a budget, The Orion the same and the Lumicon is the filter of choice over ALL others IMHO if you don't mind spending top dollar for all of your gear....and we all know it can get rather costly.

One more thing to take into consideration is the 2" filter threads. Some of them are funky and screwing them onto eyepieces in the dark can be a battle in frustration. For now I am putting my Celestron O-III and Orion Ultrablock on extension tubes so I don't have to screw them onto eyepieces.

Dyslexic Nam, (Shaun), has his filters on a 2" Orion Filter Wheel, which I may end up going with.

SEE HERE

You can also get an Astrocrumb Filter Slide which is also a great way to change filters.

SEE HERE ALSO

Quote:

There are many websites that show test results for particular filters, but in the case of your 3 choices, from wide at the top of the list to narrow at the bottom, they are:
Orion (about 15nm, IIRC)
Lumicon (about 12nm)
Baader (about 8.5nm)

The Baader "clips" the 496nm O-III line at about 50% transmission, but since the primary emission in the O-III lines is at 501nm, that doesn't seem to hurt that much.
Frankly, all 3 filters are good, so you won't lose with any of them.
But the Baader will likely give the maximum contrast.

In a small scope, the extremely narrow bandwidth will darken the sky and stars and make the field perhaps unaesthetically dark.
Sometimes there is a reason for a slightly wider bandwidth.
Not only do we want an enhanced nebula image--sometimes the "context" is important, too.




Don Pensack is absolutely right.

Cheers,


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Traveler
Pooh-Bah


Reged: 08/19/07

Loc: The Netherlands
Re: OIII Filter Choice new [Re: rick-SeMI]
      #5432682 - 09/21/12 01:06 PM

Don't forget to look for an Astronomik OIII filter as well.

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rick-SeMI
sage


Reged: 01/08/11

Loc: Michigan - USA
Re: OIII Filter Choice new [Re: Starman1]
      #5432706 - 09/21/12 01:24 PM

Don,

Found a few spectrum diagrams.
OIII Group A, B and Narrow Band


http://www.karmalimbo.com/aro/pics/filters/o3a.jpg

http://www.karmalimbo.com/aro/pics/filters/o3b.jpg

http://www.karmalimbo.com/aro/pics/filters/narrow.jpg


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rick-SeMI
sage


Reged: 01/08/11

Loc: Michigan - USA
Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5432710 - 09/21/12 01:27 PM

Markus,
The Lumicon OIII which normally sells for $140 is on sale for $99.95


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David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: OIII Filter Choice new [Re: rick-SeMI]
      #5432772 - 09/21/12 01:58 PM

Quote:

Does anyone know of a site that shows the spectrum (wavelength) in nm that is allowed for the different OIII filters ?
Right now my choice for OIII is either the Baader, Lumicon or Orion 1.25 inch filters.

M97 the Owl Nebula is the target with an Orion XT10i.
Which OIII filter would be best suited for this one?

I figure if it is good for M97, it should be pretty good for the other nebula's ?

Thanks




Here is a site that has some of the current OIII filters transmission curves:

http://www.astroamateur.de/filter/oiii.html

I still like the Lumicon OIII (if you can get one), but the DGM Optics OIII or Thousand Oaks OIII are pretty good as well. Clear skies to you.


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: OIII Filter Choice new [Re: rick-SeMI]
      #5432775 - 09/21/12 01:59 PM

Quote:

Markus,
The Lumicon OIII which normally sells for $140 is on sale for $99.95




All of my filters are 2" size, as you can see in my sig. Was that sale for a 2" Lumicon O-III? I doubt it, plus I am ok with what I have right now. I just looked here in Canada and the 2" Lumicon O-III sells for $240.00 + tax + shipping, LOL. This is exactly WHY I am keeping what I have right now.

Quote:

The Baader O-III works extremely good on the Veil and other targets. I own the Celestron which is the Baader re-branded. The Lumicon indeed has a wider bandpass as I did a test with a friend in a dark sky situation, and I found the Lumicon slightly better on M-17 and a few other targets. However, I see no point in selling off my Celestron / Baader O-III for a touch wider bandpass.





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David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: OIII Filter Choice new [Re: Traveler]
      #5432786 - 09/21/12 02:01 PM

Quote:

Don't forget to look for an Astronomik OIII filter as well.




The Astronomik filter is a little on the broad side in terms of bandwidth, so I would probably pass on it. If you want the contrast, you have to have a filter that just lets through the two OIII lines and almost nothing else. Lumicon's OIII would be my first choice with the Thousand Oaks OIII a close 2nd. Clear skies to you.


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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: OIII Filter Choice new [Re: rick-SeMI]
      #5432824 - 09/21/12 02:12 PM

Quote:

Don,

Found a few spectrum diagrams.
OIII Group A, B and Narrow Band


http://www.karmalimbo.com/aro/pics/filters/o3a.jpg

http://www.karmalimbo.com/aro/pics/filters/o3b.jpg

http://www.karmalimbo.com/aro/pics/filters/narrow.jpg



It should be noted that these are not test reports, merely the superimposition of many manufacturers' bandwidth diagrams.
Great illustrations, though.


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mitaccio
professor emeritus
*****

Reged: 03/17/09

Loc: Oahu, Hawaii
Re: OIII Filter Choice new [Re: Starman1]
      #5432889 - 09/21/12 02:57 PM

I bought my OPT OIII 1.25" a year ago for about $40, best investment I have made.

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Cabrillas
member


Reged: 07/19/09

Loc: Madrid. Spain.
Re: OIII Filter Choice new [Re: mitaccio]
      #5433188 - 09/21/12 05:45 PM

Another vote for the Astronomik. I've compared it against others, and it is the best in my refractor. A friend has a C9.5. We checked the Astronomik against the Baader in both scopes. We agreed the astronomik was the clear winner.

But of course beware that the performance of such restrictive filters are very affected by aperture and quality of the sky. Regards.


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turtle86
Pooh-Bah Everywhere Else
*****

Reged: 10/09/06

Re: OIII Filter Choice new [Re: Cabrillas]
      #5433268 - 09/21/12 06:57 PM

Quote:

Another vote for the Astronomik. I've compared it against others, and it is the best in my refractor. A friend has a C9.5. We checked the Astronomik against the Baader in both scopes. We agreed the astronomik was the clear winner.

But of course beware that the performance of such restrictive filters are very affected by aperture and quality of the sky. Regards.




Yet another vote for the Astronomick. I have the narrow band, OIII and H-beta filters all on a filter slide. All work great for me. The OIII might be a little broader than the Lumicon, etc., but the Veil really pops out when I use it in my scope, showing exquisite filamentary detail. Another standout is Thor's Helmet. Just a great filter for planetary nebulae (and the Veil).

Two things I really like about the Astronomick. One, they have very durable coatings, which are essentially scratch-proof and impervious to dew. Two, the view is very aesthetically pleasing, with nice pinpoint stars. In contrast, a couple of the other OIII filters I've seen (the older version of the Lumicon specifically comes to mind) yielded rather funky-looking bloated stars...


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John Huntley
scholastic sledgehammer
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Reged: 07/16/06

Loc: South West England
Re: OIII Filter Choice new [Re: turtle86]
      #5433341 - 09/21/12 07:42 PM

And yet another Astronomik O-III advocate here. I like it for the same reasons that Rob describes well above.

Prior to the Astronomik I'd tried the Telescope Services 0-III (which is the same as the Skywatcher one) and the Baader and Celestron O-III's which are, again, the same as each other.

I find the Astronomik O-III works very effectively in all my scopes from 4 to 10 inches in aperture.

Edited by John Huntley (09/21/12 07:43 PM)


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rocketsteve
sage
*****

Reged: 04/17/11

Loc: Southeast Louisiana
Re: OIII Filter Choice new [Re: turtle86]
      #5433360 - 09/21/12 07:52 PM

Quote:

Quote:

Another vote for the Astronomik. I've compared it against others, and it is the best in my refractor. A friend has a C9.5. We checked the Astronomik against the Baader in both scopes. We agreed the astronomik was the clear winner.

But of course beware that the performance of such restrictive filters are very affected by aperture and quality of the sky. Regards.




Yet another vote for the Astronomick. I have the narrow band, OIII and H-beta filters all on a filter slide. All work great for me. The OIII might be a little broader than the Lumicon, etc., but the Veil really pops out when I use it in my scope, showing exquisite filamentary detail. Another standout is Thor's Helmet. Just a great filter for planetary nebulae (and the Veil).

Two things I really like about the Astronomick. One, they have very durable coatings, which are essentially scratch-proof and impervious to dew. Two, the view is very aesthetically pleasing, with nice pinpoint stars. In contrast, a couple of the other OIII filters I've seen (the older version of the Lumicon specifically comes to mind) yielded rather funky-looking bloated stars...




And I'd like to register another vote for the Astronomik O-III filter. Rob's experiences are very similar to my own. His experiences with the Veil and Thor's Helmet are right on the money. Overall, I'm completely satisfied with my filter purchase.


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5433568 - 09/21/12 10:36 PM

The Celestron and Baader versions are identical - except in price. Celestron-branded O-IIIs run about 30% less than the Baader versions of the same filters.

I use it successfully in scopes from 2.7" to 16". It works just fine. I also have an Orion-branded O-III. Despite "on paper" differences, at the eyepiece there's not much difference between it and the Celestron.

Regards,

Jim


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drollere
Pooh-Bah
*****

Reged: 02/02/10

Loc: sebastopol, california
Re: OIII Filter Choice new [Re: jrbarnett]
      #5433602 - 09/21/12 10:57 PM

i agree with david, the thousand oaks is a very good OIII filter, but note i use it for visual only.

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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: OIII Filter Choice new [Re: turtle86]
      #5433727 - 09/22/12 12:37 AM

Quote:

Quote:

Another vote for the Astronomik. I've compared it against others, and it is the best in my refractor. A friend has a C9.5. We checked the Astronomik against the Baader in both scopes. We agreed the astronomik was the clear winner.

But of course beware that the performance of such restrictive filters are very affected by aperture and quality of the sky. Regards.




Yet another vote for the Astronomick. I have the narrow band, OIII and H-beta filters all on a filter slide. All work great for me. The OIII might be a little broader than the Lumicon, etc., but the Veil really pops out when I use it in my scope, showing exquisite filamentary detail. Another standout is Thor's Helmet. Just a great filter for planetary nebulae (and the Veil).

Two things I really like about the Astronomick. One, they have very durable coatings, which are essentially scratch-proof and impervious to dew. Two, the view is very aesthetically pleasing, with nice pinpoint stars. In contrast, a couple of the other OIII filters I've seen (the older version of the Lumicon specifically comes to mind) yielded rather funky-looking bloated stars...




The point to be made here is that a slightly narrower bandwidth would enhance the contrast more, but at the expense of the stars. So which do you use the nebula filter for--nebulae, or views of stars? I'm not being sarcastic because there really is a difference in preference involved.
The TeleVue O-III is a broader one and also of superlative quality. It really does depend on preference.


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David Knisely
Postmaster
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Reged: 04/19/04

Loc: southeastern Nebraska
Re: OIII Filter Choice new [Re: Cabrillas]
      #5433758 - 09/22/12 01:24 AM

Quote:

Another vote for the Astronomik. I've compared it against others, and it is the best in my refractor. A friend has a C9.5. We checked the Astronomik against the Baader in both scopes. We agreed the astronomik was the clear winner.

But of course beware that the performance of such restrictive filters are very affected by aperture and quality of the sky. Regards.




The problem with the Astronomik OIII isn't that it doesn't work (it works fairly well). It is just that its bandwidth is nearly as broad as some of the narrow-band filters that let in both the OIII emission lines as well as the H-Beta line. The Astronomik has a full width at Half Maximum (FWHM) of a whopping 204 angstroms (the Lumicon OIII is around 115 angstroms for example). The DGM Optics NPB filter has a FWHM figure of nearly 230 angstroms and I suspect that the views with it would equal that of the Astronomik OIII, not to mention that the DGM NPB would be useful on more nebular objects than a standard OIII might be useful on. If you want a halfway decent "true" OIII filter, I might suggest the DGM Optics OIII filter, as it is close to the bandwidth of the Lumicon OIII. Clear skies to you.


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Greg77
super member


Reged: 05/02/09

Loc: Slovenia, EU
Re: OIII Filter Choice new [Re: John Huntley]
      #5433780 - 09/22/12 01:53 AM

Quote:

Prior to the Astronomik I'd tried the Telescope Services 0-III (which is the same as the Skywatcher one) and the Baader...




John,

...how would you describe diference between TS and Astronomik in terms of contrast and brightness of background stars (field)?

CS!

Greg


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Giorgos
super member


Reged: 01/14/11

Loc: Athens, Greece
Re: OIII Filter Choice new [Re: Greg77]
      #5433825 - 09/22/12 03:01 AM

I have tried side by side the Lumicon and the Meade O-III (908X). The nebulae trough both of them seem more or less the same the Lumicon gave a pinkish tint to stars though. I prefer the Meade that shows more natural color on stars.

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Richard Low
professor emeritus
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Reged: 11/27/05

Loc: 1 deg N, GMT+8hrs
Re: OIII Filter Choice new [Re: Giorgos]
      #5433827 - 09/22/12 03:11 AM

I have the Celestron O-III which works well with great contrast on the Veil Neb. in my 15" dob. I recommend to get filters in 2" versions as it is very useful on 2" widefield eyepieces 30-40mm.

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reiner
sage
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Reged: 09/28/05

Loc: Freiburg, Germany
Re: OIII Filter Choice new [Re: David Knisely]
      #5433848 - 09/22/12 03:57 AM

Quote:

The Astronomik has a full width at Half Maximum (FWHM) of a whopping 204 angstroms (the Lumicon OIII is around 115 angstroms for example).




Hi David,

this is true for the older Astronomic OIII filters. According to their website, they have reduced the bandwidth now to 12nm, which is perfect for an OIII filter. It is on the german webpage only
http://www.astronomik.com/de/visual-filters/oiii-filter-visuell.html

I haven't tried one of these newer ones, though.

@all: I have compared extensively the Baader and the Lumicon. Sure, the Baader offers excellent contrast on the Veil and other bright OIII sources. If it comes to faint targets, like some faint Abell PNe, the Lumicon is a considerably better choice.


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: OIII Filter Choice new [Re: reiner]
      #5433858 - 09/22/12 04:19 AM

I don't see why some people have to be so "nit picky" about a few Nm here. Sure the Lumicon has a wider bandpass, but there really is NO POINT in spending $200.00 or more on a 2" filter when you can pretty much get the same results with the Baader / Celestron. This is supposed to be a "fun hobby", not a competitive one.

If you feel the need to go out and blow that kinda cash all the power to ya bro, knock yourself out,


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sixela
Postmaster
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Reged: 12/23/04

Loc: Boechout, Belgium
Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5433862 - 09/22/12 04:27 AM

Well, "a couple of nm" makes a lot of difference. One of the two OIII emission lines is only partially transmitted on the Baader on some samples.

As Reiner said, it can help on some things and hinder on others.


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David Knisely
Postmaster
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Reged: 04/19/04

Loc: southeastern Nebraska
Re: OIII Filter Choice new [Re: reiner]
      #5433869 - 09/22/12 04:47 AM

Quote:

Quote:

The Astronomik has a full width at Half Maximum (FWHM) of a whopping 204 angstroms (the Lumicon OIII is around 115 angstroms for example).




Hi David,

this is true for the older Astronomic OIII filters. According to their website, they have reduced the bandwidth now to 12nm, which is perfect for an OIII filter. It is on the german webpage only
http://www.astronomik.com/en/visual-filters/oiii-filter-visuell.html

I haven't tried one of these newer ones, though.

@all: I have compared extensively the Baader and the Lumicon. Sure, the Baader offers excellent contrast on the Veil and other bright OIII sources. If it comes to faint targets, like some faint Abell PNe, the Lumicon is a considerably better choice.




It would be nice if an independent spectrophotometer transmission curve would be provided by Astronomik (even Orion does that). The PDF sheet shows a "generic" curve which can be roughly estimated to have a FWHM of about 123 angstroms which, if accurate, could work pretty well (about as well as the Lumicon OIII).

However, I have to take strong issue with what Astronomik says about the OIII filter:

"Since enough light must be available to make use of the OIII filter it is best to use this filter with apertures of more than 6" (150mm). Smaller instruments do not gather enough light for meaningful and satisfying astronomical work."

This is an often-quoted myth and is definitely *not* true. As I have stated in the past, I have used the OIII in apertures of 50mm and larger with good results. Indeed, one of my favorite views of the North America Nebula comes in my 100mm aperture f/6 refractor at 15x and 25x using the OIII filter, so it definitely does work in smaller scopes. The larger the aperture, the more objects (and detail) will be visible that the OIII will help with, but this does not mean that its use is limited to apertures larger than six inches. It would be nice if Astronomik would not continue to perpetuate this myth. Clear skies to you.


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: OIII Filter Choice new [Re: Starman1]
      #5433885 - 09/22/12 05:47 AM

Quote:


The point to be made here is that a slightly narrower bandwidth would enhance the contrast more, but at the expense of the stars. So which do you use the nebula filter for--nebulae, or views of stars? I'm not being sarcastic because there really is a difference in preference involved.




Don:

A good point... Myself, when I want to enhance the view and but still see a good number of stars, I use an Orion Ultrablock. When I want to maximize the contrast, I use a narrow band filter.

Jon


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Traveler
Pooh-Bah


Reged: 08/19/07

Loc: The Netherlands
Re: OIII Filter Choice new [Re: David Knisely]
      #5434023 - 09/22/12 08:42 AM

That is true David about the OIII and aperture myth. I use my Astronomik OIII filter even with my Tak FS60C and enjoyed the views very much. That is what i learned from you by the way.

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David Knisely
Postmaster
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Reged: 04/19/04

Loc: southeastern Nebraska
Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5434516 - 09/22/12 02:01 PM

Quote:

I don't see why some people have to be so "nit picky" about a few Nm here. Sure the Lumicon has a wider bandpass, but there really is NO POINT in spending $200.00 or more on a 2" filter when you can pretty much get the same results with the Baader / Celestron. This is supposed to be a "fun hobby", not a competitive one.

If you feel the need to go out and blow that kinda cash all the power to ya bro, knock yourself out,




Well, it isn't really "competition". There have been a number of reports of somewhat variable quality in the lower priced OIII filters like those from Zhumell and Celestron. With these extremely narrow bandwidth filters, any notable variation in the transmission characteristics can result in vastly different performance. The Baader in particular is quite narrow, so it cuts a little into the 4959 angstrom OIII line, while the slightly broader filters transmit it. I suspect that the Celestron filters (if they are actually re-branded Baaders) may be produced in-bulk in ways that cause less than high quality filters to get through. For the most part, the higher priced filters tend to be made with somewhat more consistent passband locations and widths, which is one reason I have always bought from Lumicon. This does not mean that you will always get a perfect filter from them, but in my experience, the quality of the Lumicon filters has been fairly high. With the Celestrons, well, it looks like kind of a roll of the dice. Clear skies to you.


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turtle86
Pooh-Bah Everywhere Else
*****

Reged: 10/09/06

Re: OIII Filter Choice new [Re: Starman1]
      #5434542 - 09/22/12 02:21 PM

Quote:

Quote:

Quote:

Another vote for the Astronomik. I've compared it against others, and it is the best in my refractor. A friend has a C9.5. We checked the Astronomik against the Baader in both scopes. We agreed the astronomik was the clear winner.

But of course beware that the performance of such restrictive filters are very affected by aperture and quality of the sky. Regards.




Yet another vote for the Astronomick. I have the narrow band, OIII and H-beta filters all on a filter slide. All work great for me. The OIII might be a little broader than the Lumicon, etc., but the Veil really pops out when I use it in my scope, showing exquisite filamentary detail. Another standout is Thor's Helmet. Just a great filter for planetary nebulae (and the Veil).

Two things I really like about the Astronomick. One, they have very durable coatings, which are essentially scratch-proof and impervious to dew. Two, the view is very aesthetically pleasing, with nice pinpoint stars. In contrast, a couple of the other OIII filters I've seen (the older version of the Lumicon specifically comes to mind) yielded rather funky-looking bloated stars...




The point to be made here is that a slightly narrower bandwidth would enhance the contrast more, but at the expense of the stars. So which do you use the nebula filter for--nebulae, or views of stars? I'm not being sarcastic because there really is a difference in preference involved.
The TeleVue O-III is a broader one and also of superlative quality. It really does depend on preference.




No sarcasm taken, but I was actually talking about the quality of the stars being seen, not the quantity. I used to have one of the older Lumicon OIII filters, but the stars were bloated or halated. In comparing it to the Astronomik, I found that the latter yielded much nicer stars and enhanced the contrast at least as much. I agree with Jon that it's helpful to have different filters depending on how much contrast you want. With my filter slide I like to switch back and forth between the OIII and narrowband when viewing a nebula--for some objects one filter will clearly work much better than the other (Veil and OIII, Horsehead and H-beta, etc.), but for a lot of objects both the OIII and narrowband filters work pretty well, with each filter emphasizing different nebular details.


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turtle86
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Re: OIII Filter Choice new [Re: reiner]
      #5434546 - 09/22/12 02:23 PM

Quote:

Quote:

The Astronomik has a full width at Half Maximum (FWHM) of a whopping 204 angstroms (the Lumicon OIII is around 115 angstroms for example).




Hi David,

this is true for the older Astronomic OIII filters. According to their website, they have reduced the bandwidth now to 12nm, which is perfect for an OIII filter. It is on the german webpage only
http://www.astronomik.com/de/visual-filters/oiii-filter-visuell.html

I haven't tried one of these newer ones, though.

@all: I have compared extensively the Baader and the Lumicon. Sure, the Baader offers excellent contrast on the Veil and other bright OIII sources. If it comes to faint targets, like some faint Abell PNe, the Lumicon is a considerably better choice.




Interesting. I wonder when Astronomik made that change.


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Scanning4Comets
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Re: OIII Filter Choice new [Re: turtle86]
      #5434579 - 09/22/12 02:41 PM

Don:

Quote:

A good point... Myself, when I want to enhance the view and but still see a good number of stars, I use an Orion Ultrablock. When I want to maximize the contrast, I use a narrow band filter.

Jon




This is only good if the object in question emits the right emission lines and you need the right filter for maximum contrast. Makes no sense having to use an Ultrablock on an object that would need an O-III filter for the best contrast and having the need to see more "stars". The whole point is to maximize contrast on the nebula and not stars.

Quote:

No sarcasm taken, but I was actually talking about the quality of the stars being seen, not the quantity. I used to have one of the older Lumicon OIII filters, but the stars were bloated or halated. In comparing it to the Astronomik, I found that the latter yielded much nicer stars and enhanced the contrast at least as much.




As far as "stars" go filter wise, these filters are meant to enhance the view of nebulae, not stars. The only reason you would need to see any stars in an O-III or UHC / Ultrablock filter is for focusing. True what you said David about more expensive filters having better QC, I guess I was lucky with my Celestron O-III as it does work really well.

O-III filters work best when fully dark adapted with the right exit pupil. I find mine is only too dark when I am not adapted to the darkness and excellent when I am fully dark adapted. I have also tried it at higher powers, with less than satisfactory results. This is when I pull out the Orion Ultrablock because it has a wider bandpass. If the nebula requires an O-III filter at higher powers, I'll try to gain maximum contrast by not bumping the power up too much.

So for me, I now use my Celestron O-III filter with my 38mm Orion Q-70, 17mm Baader Hyperion, (which will be replaced with an 18mm Meade HD 60), 10.5mm pentax XL, and once in a while on my 7mm XW, but rarely on the 7mm XW at all. At higher powers I'll switch to the Ultrablock and sometimes I will use the Ultrablock at lower powers because the nebulae in question will emit certain lines in which the Ultrablock shows better contrast.

Good examples are M-8, M-27, M-20, etc.

38mm Q70: 7.9mm exit pupil
17mm Hyperion: 3.7mm exit pupil
10.5mm XL: 2.4mm exit pupil
7mm XW: 1.6mm exit pupil

Cheers,


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turtle86
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Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5434627 - 09/22/12 03:13 PM

Quote:

As far as "stars" go filter wise, these filters are meant to enhance the view of nebulae, not stars.




No disagreement there, but if two filters enhance the view of nebulae equally well but one of them also has tighter stars, why not get the filter that does both well?


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Scanning4Comets
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Re: OIII Filter Choice new [Re: turtle86]
      #5434635 - 09/22/12 03:16 PM

I re-edited my post. If you have read an earlier post I made, two friends and myself tested my Celestron O-III along with a Lumicon O-III. The Lumicon showed a wider bandpass and a few more stars, with "stars" not being of importance. The difference wasn't huge or big by any margin, but it was there to a "slight" degree. The test was done on M-17, The Swan, or "Omega" Nebula.

I just don't see the point in running out to spend over $200.00 + to get a 2" Lumicon for 4 Nm more of bandpass when I am happy with the Celestron O-III. Others may want to do that, which is ok. Mine is probably worth $80.00 or just less than that. This is my point. I can more than get by with what I have now and the results are more than satisfactory. I used to own Lumicon filters exclusively and I *can* see a very "slight" difference, but to me the difference isn't that much at all.

Cheers,


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Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5434705 - 09/22/12 04:10 PM

The biggest difference is throughput. The Baader filter is a very "dark" O-III filter due to its tighter bandpass and less efficient throughput on those bands that it does pass. As another poster said, it works better with brighter O-III sources in smaller scopes or larger scopes, but honestly in a small aperture scope you're not going to be looking at many dim O-III sources anyway.

In a big scope, the lower transmission of the Baader is less relevant save for threshold targets, and for those, there's always a bigger scope. To me, the job of a filter is contrast, not natural stars or a lot of stars. I'd rather have my starry vistas entirely unadulterated by a filter. But for those who like a mix of stars with their O-III sources, I'd look at a gentle filter like the Televue O-III. Lower contrast on O-III sources, but a nice mix of broader spectrum sources and enhanced O-III sources.

Regards,

Jim


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Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5434816 - 09/22/12 05:46 PM

Quote:

A good point... Myself, when I want to enhance the view and but still see a good number of stars, I use an Orion Ultrablock. When I want to maximize the contrast, I use a narrow band filter.

Jon

Quote:






This is only good if the object in question emits the right emission lines and you need the right filter for maximum contrast. Makes no sense having to use an Ultrablock on an object that would need an O-III filter for the best contrast and having the need to see more "stars". The whole point is to maximize contrast on the nebula and not stars.





Wait, wait...

You seem to be solely focused on maximizing the contrast of the nebula you are observing. Don added an interesting perspective, it's up to the observer, one does not have to be solely focused on getting the best possible view of the nebula, sometimes seeing the starfield and the nebula is of interest.

As I pointed out, if that is my interest at the moment, then I will use the Ultrablock, it provides a nice balance because it enhances the contrast of many nebulae while still showing a reasonable starfield. M8, M17, the Rosette, these are few that have interesting starfields and are bright enough the Ultrablock makes for a pleasing view.

Of course, there are times too when I am interested in maximizing the contrast of an object, then I will use either an O-III filter or an H-Beta... This is most often the case, the Ultrablock gets relatively little use in comparison.

So as Don pointed out, it's a choice we all have. And too, we all have the choice of viewing without any filtering. That is good too.

As far as the Celestron O-III goes. I reported here a comparison a friend and I did between my Celestron O-III, his Celestron O-III and the TV Bandmate O-III. We used a 17.5 inch Dob. The object was the Veil and my Celestron O-III showed the most contrast, the TV definitely enhanced the contrast, the other Celestron O-III was barely better than nothing.

But since then, I have not seen other reports of poor performing Celestron O-III filters and I have seen many reports that they are good performers so I have to think my friend's was an anomaly rather than typical.

Jon


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MadHungarian
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Re: OIII Filter Choice new [Re: reiner]
      #5435347 - 09/23/12 12:56 AM

Quote:


...
this is true for the older Astronomic OIII filters. According to their website, they have reduced the bandwidth now to 12nm, which is perfect for an OIII filter. It is on the german webpage only
http://www.astronomik.com/de/visual-filters/oiii-filter-visuell.html
...





I'm the market for a middling-narrow OIII myself, so then it looks like the new Astronomik might be the one for me (I'd do Lumicon, but they seem to have dropped off the face of the earth). Astronomik hadn't been my front-runners before because they had a reputation as being wider, and i already have a (wider) UHC.

But the $199 question is, how do i know i'm getting one of the new Astronomiks? If i buy from Opt/etc today, i'm most likely getting a unit they've had in stock for awhile, so it'll probably be an old one.

Though I have another concern -- I ran the webpage above through Google Translate and i see no mention of recent changes to the filter, so is there any way of finding out if the filter bandwith actually has changed or whether the 12nm figure it mentions is just a webpage mistake?


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Starman1
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Re: OIII Filter Choice new [Re: Jon Isaacs]
      #5435348 - 09/23/12 12:56 AM

Since 2005, the bandwidth of the Lumicon O-III has excluded red colors, so there is no visible red in the newer Lumicon filters.
They changed the filters BECAUSE people complained about the lack of tightness of the star images. It turned out that red and blue-green weren't focused at exactly the same point and this bloated the stars.
My current version (well, 2010), has only blue-green transmission. When you look through it in the daytime, that's all you see. I have an older 1.25" one which appears reddish when you look through it in the daytime. In that one, there was a broad swath of red that was transmitted.


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David Knisely
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Re: OIII Filter Choice new [Re: turtle86]
      #5435351 - 09/23/12 01:01 AM

turtle86 wrote:

Quote:

No sarcasm taken, but I was actually talking about the quality of the stars being seen, not the quantity. I used to have one of the older Lumicon OIII filters, but the stars were bloated or halated.




Those were the very old laminated filters. Lumicon no longer uses that method of protection. In addition, Lumicon's OIII no longer has the "red leak" secondary passband, so the images of stars tend to be not terribly "bloated" or having red secondary star images anymore (at least mine doesn't). Clear skies to you.


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reiner
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Re: OIII Filter Choice new [Re: MadHungarian]
      #5435465 - 09/23/12 03:42 AM

Quote:

... so is there any way of finding out if the filter bandwith actually has changed or whether the 12nm figure it mentions is just a webpage mistake?




It is no mistake, there was a change. A friend of mine has tested older and newer versions of the Astronomik OIII (and the Baader/Celestron). Check his results here (you might need to ask him for the manufacturing dates or write directly to Gerd Neumann at astronomik.com)

http://www.blackskynet.de/bandpassfilter.html

It looks like the position of the pass band is not ideal, at least not with his sample of the Astronomik OIII. Furthermore, it looks like even some of the major manufacturers have problems to get their filters reproducibly straight.

I have to say that I have tested 8 Lumicon filters (mine and my club's filters) with a professional UV-vis spectrophotometer (some are displayed on this webpage http://www.astroamateur.de/filter/), and haven't observed such "outliers", all of them were perfectly within the specs.


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Traveler
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Re: OIII Filter Choice new [Re: reiner]
      #5435568 - 09/23/12 07:15 AM

What do you mean Reiner, with older and newer? Is older 3 years or something?

Very informative graphics.


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Re: OIII Filter Choice new [Re: David Knisely]
      #5435866 - 09/23/12 10:51 AM

Quote:

This is an often-quoted myth and is definitely *not* true. As I have stated in the past, I have used the OIII in apertures of 50mm and larger with good results. Indeed, one of my favorite views of the North America Nebula comes in my 100mm aperture f/6 refractor at 15x and 25x using the OIII filter, so it definitely does work in smaller scopes. The larger the aperture, the more objects (and detail) will be visible that the OIII will help with, but this does not mean that its use is limited to apertures larger than six inches. It would be nice if Astronomik would not continue to perpetuate this myth. Clear skies to you.




Same here. I have an older (late '90's) Lumicon OIII. With my 105mm f6 refractor and an appropriate eyepiece I get a gorgeous view of the Veil.

David, how do the newer Lumicons compare to an older one like mine? The label on the back of the plastic case says:

<<< PREMIUM
Nebula Line Transmission %
Oxygen - III 496nm 94
Oxygen - III 501nm 95
Hydrogen-Beta 486nm 0.3 >>

The label is pre-printed with the exception of the transmission % numbers at each bandwidth and the word Premium which are hand written in ink. I assume they tested each filter and sold as premium those with the better actual measurements. My Deep Sky is similarly labeled with an additional line for transmsision at 491nm handwritten in.


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KidOrion
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Re: OIII Filter Choice new [Re: David Knisely]
      #5435877 - 09/23/12 10:59 AM

Quote:

turtle86 wrote:

Quote:

No sarcasm taken, but I was actually talking about the quality of the stars being seen, not the quantity. I used to have one of the older Lumicon OIII filters, but the stars were bloated or halated.




Those were the very old laminated filters. Lumicon no longer uses that method of protection. In addition, Lumicon's OIII no longer has the "red leak" secondary passband, so the images of stars tend to be not terribly "bloated" or having red secondary star images anymore (at least mine doesn't). Clear skies to you.




David--

About what year did Lumicon make the switch? My Lumicon O-III is late 80s/early 90s vintage, and it seems to have considerably degraded over time to where I can no longer get pinpoint stars through it.


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Re: OIII Filter Choice new [Re: Starman1]
      #5436049 - 09/23/12 12:49 PM

Quote:

The point to be made here is that a slightly narrower bandwidth would enhance the contrast more, but at the expense of the stars. So which do you use the nebula filter for--nebulae, or views of stars? I'm not being sarcastic because there really is a difference in preference involved.




it's worth noting as context that nearly all nebulae are structurally involved with stars, either stars the nebula has recently created or the star that created the nebula. nebulae without stars do not appear in the visual wavelengths, unless they are involved with enough dust to block light. it might make sense to block out stars entirely, if that gave a better image of gas structure inside the nebula, but i wouldn't prefer that because it censors the associated stars that are essential to grasp the nebula context.

this detailed discussion of bandwidth an interesting example of how a complex issue can become displaced by a focus on narrow technical criteria. if the application is photography, then the choice of filter would depend on what other filters (if any) are used to build the final image, and what the image will be used for; if the application is visual, then the choice might be called esthetic. a transmission profile by itself won't decide the issue; you may have to look for yourself.

the OP focused on M97 as the criterion object, which to me is not dramatically enhanced by an OIII filter.


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rick-SeMI
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Re: OIII Filter Choice new [Re: KidOrion]
      #5436067 - 09/23/12 01:02 PM

Thanks for all the good info.
It helps me decide which OIII to choose.
But, if I were to use the waveform graphs in my post #5432706, I would choose, according to the graphs.
Using O-III Group A because the filters in Group B transmission characteristics bottom out around 90%.
1) Televue - because it allows 496 and 501 nm at 100% transmission and almost flat towards the violet and red spectrum.
2) Astronomik - 496 just below 97% and 501 99%
3) Lumicon - 496 at 99% but clips 501 around 90%

I have the Orion Ultra Block and DGM NPB (Nebula) filters.
The graphs for these two are similiar to a couple of the OIII filters

So, anyone want to take on the question of which would be better for M-97, the Owl Nebula ?


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Re: OIII Filter Choice new [Re: rick-SeMI]
      #5436182 - 09/23/12 01:58 PM

Quote:

Thanks for all the good info.
It helps me decide which OIII to choose.
But, if I were to use the waveform graphs in my post #5432706, I would choose, according to the graphs.
Using O-III Group A because the filters in Group B transmission characteristics bottom out around 90%.
1) Televue - because it allows 496 and 501 nm at 100% transmission and almost flat towards the violet and red spectrum.
2) Astronomik - 496 just below 97% and 501 99%
3) Lumicon - 496 at 99% but clips 501 around 90%

I have the Orion Ultra Block and DGM NPB (Nebula) filters.
The graphs for these two are similiar to a couple of the OIII filters

So, anyone want to take on the question of which would be better for M-97, the Owl Nebula ?




For the Owl, a 'true' OIII filter like the Lumicon or Thousand Oaks would probably be best. The NPB will help as well, but perhaps with not quite as much contrast as the narrower OIII filters. As for Tele Vue's Bandmate OIII, that one is *WAY* too wide (nearly as wide as the NPB), so I would pass on getting that filter. As for "100% transmission", no commonly manufactured filter has that despite whatever passband plots you will see. The most one might expect for most production filters like these is in the high 90's (perhaps 97% or so at one wavelength). In any case, the human eye cannot easily detect a change in brightness of less than 10%, so if an OIII filter has a transmission of around 88% or more at one or both of the OIII lines (and has a Full Width at Half Maximum bandwidth of less than 15 nm but more than 8.5 nm), it should work just fine for visual use. Clear skies to you.


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David Knisely
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Re: OIII Filter Choice new [Re: Paul G]
      #5436194 - 09/23/12 02:04 PM

Quote:

Quote:

This is an often-quoted myth and is definitely *not* true. As I have stated in the past, I have used the OIII in apertures of 50mm and larger with good results. Indeed, one of my favorite views of the North America Nebula comes in my 100mm aperture f/6 refractor at 15x and 25x using the OIII filter, so it definitely does work in smaller scopes. The larger the aperture, the more objects (and detail) will be visible that the OIII will help with, but this does not mean that its use is limited to apertures larger than six inches. It would be nice if Astronomik would not continue to perpetuate this myth. Clear skies to you.




Same here. I have an older (late '90's) Lumicon OIII. With my 105mm f6 refractor and an appropriate eyepiece I get a gorgeous view of the Veil.

David, how do the newer Lumicons compare to an older one like mine? The label on the back of the plastic case says:

<<< PREMIUM
Nebula Line Transmission %
Oxygen - III 496nm 94
Oxygen - III 501nm 95
Hydrogen-Beta 486nm 0.3 >>

The label is pre-printed with the exception of the transmission % numbers at each bandwidth and the word Premium which are hand written in ink. I assume they tested each filter and sold as premium those with the better actual measurements. My Deep Sky is similarly labeled with an additional line for transmsision at 491nm handwritten in.




The newer ones are a little better than those sold in the late 1980's and into the 1990's that still used the laminated protection. The 2" one I have was purchased in the mid 2000's and has fairly good star image quality and no significant secondary passbands outside of the primary one (transmission values of around 94% to 96% depending on which OIII line you are looking at). Clear skies to you.


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Paul G
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Re: OIII Filter Choice new [Re: David Knisely]
      #5436811 - 09/23/12 07:24 PM

Quote:

Quote:

Quote:

This is an often-quoted myth and is definitely *not* true. As I have stated in the past, I have used the OIII in apertures of 50mm and larger with good results. Indeed, one of my favorite views of the North America Nebula comes in my 100mm aperture f/6 refractor at 15x and 25x using the OIII filter, so it definitely does work in smaller scopes. The larger the aperture, the more objects (and detail) will be visible that the OIII will help with, but this does not mean that its use is limited to apertures larger than six inches. It would be nice if Astronomik would not continue to perpetuate this myth. Clear skies to you.




Same here. I have an older (late '90's) Lumicon OIII. With my 105mm f6 refractor and an appropriate eyepiece I get a gorgeous view of the Veil.

David, how do the newer Lumicons compare to an older one like mine? The label on the back of the plastic case says:

<<< PREMIUM
Nebula Line Transmission %
Oxygen - III 496nm 94
Oxygen - III 501nm 95
Hydrogen-Beta 486nm 0.3 >>

The label is pre-printed with the exception of the transmission % numbers at each bandwidth and the word Premium which are hand written in ink. I assume they tested each filter and sold as premium those with the better actual measurements. My Deep Sky is similarly labeled with an additional line for transmsision at 491nm handwritten in.




The newer ones are a little better than those sold in the late 1980's and into the 1990's that still used the laminated protection. The 2" one I have was purchased in the mid 2000's and has fairly good star image quality and no significant secondary passbands outside of the primary one (transmission values of around 94% to 96% depending on which OIII line you are looking at). Clear skies to you.




Thx.


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rick-SeMI
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Re: OIII Filter Choice new [Re: David Knisely]
      #5436929 - 09/23/12 08:32 PM

Quote:


For the Owl, a 'true' OIII filter like the Lumicon or Thousand Oaks would probably be best. The NPB will help as well, but perhaps with not quite as much contrast as the narrower OIII filters. As for Tele Vue's Bandmate OIII, that one is *WAY* too wide (nearly as wide as the NPB), so I would pass on getting that filter. As for "100% transmission", no commonly manufactured filter has that despite whatever passband plots you will see. The most one might expect for most production filters like these is in the high 90's (perhaps 97% or so at one wavelength). In any case, the human eye cannot easily detect a change in brightness of less than 10%, so if an OIII filter has a transmission of around 88% or more at one or both of the OIII lines (and has a Full Width at Half Maximum bandwidth of less than 15 nm but more than 8.5 nm), it should work just fine for visual use. Clear skies to you.




David,
I think I am finally catching on!
Bandpass means alot also
I appreciate the info as you have had practical and in the field experience with several filters.
But, can you give me a quick definition of FWHM ?
Does it have something to do with the 496 nm and 501 nm OIII lines? Which have a difference of 5 nm.
I am confused about the 8.5 nm and 15 nm wavelength positions.

Thanks


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Re: OIII Filter Choice new [Re: rick-SeMI]
      #5437351 - 09/24/12 01:51 AM Attachment (13 downloads)

Quote:

Quote:


For the Owl, a 'true' OIII filter like the Lumicon or Thousand Oaks would probably be best. The NPB will help as well, but perhaps with not quite as much contrast as the narrower OIII filters. As for Tele Vue's Bandmate OIII, that one is *WAY* too wide (nearly as wide as the NPB), so I would pass on getting that filter. As for "100% transmission", no commonly manufactured filter has that despite whatever passband plots you will see. The most one might expect for most production filters like these is in the high 90's (perhaps 97% or so at one wavelength). In any case, the human eye cannot easily detect a change in brightness of less than 10%, so if an OIII filter has a transmission of around 88% or more at one or both of the OIII lines (and has a Full Width at Half Maximum bandwidth of less than 15 nm but more than 8.5 nm), it should work just fine for visual use. Clear skies to you.




David,
I think I am finally catching on!
Bandpass means alot also
I appreciate the info as you have had practical and in the field experience with several filters.
But, can you give me a quick definition of FWHM ?
Does it have something to do with the 496 nm and 501 nm OIII lines? Which have a difference of 5 nm.
I am confused about the 8.5 nm and 15 nm wavelength positions.

Thanks




FWHM is the full width of the filter at half of its maximum transmission level. Most narrow-band nebula filters have FWHM values in the 23 nm to 28 nm range, while good OIII line filters will have FWHM values of between 8.5 nm and about 15 nm. Generally, the filter passband of an OIII filter will be centered at a point in the visual spectrum that is roughly halfway between the 495.9 and 500.7 nm wavelengths with a peak transmission at that point. There is some slight fall-off in transmission away from that peak transmission point, but most line filters have more than 88% transmission at the two OIII lines, so there is little to worry about there. The Baader OIII is a little on the narrow side (8.5 nm FWHM passband width), as the 495.9 nm OIII line is transmitted at only between 35% and 50%, while the other line comes through at over 90%. However, typically, the 495.9 nm OIII line is weaker than the 500.7 nm line, so the Baader filter still works fairly well. Clear skies to you.


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rick-SeMI
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Re: OIII Filter Choice new [Re: David Knisely]
      #5437935 - 09/24/12 11:49 AM

Quote:


FWHM is the full width of the filter at half of its maximum transmission level. Most narrow-band nebula filters have FWHM values in the 23 nm to 28 nm range, while good OIII line filters will have FWHM values of between 8.5 nm and about 15 nm. Generally, the filter passband of an OIII filter will be centered at a point in the visual spectrum that is roughly halfway between the 495.9 and 500.7 nm wavelengths with a peak transmission at that point. There is some slight fall-off in transmission away from that peak transmission point, but most line filters have more than 88% transmission at the two OIII lines, so there is little to worry about there. The Baader OIII is a little on the narrow side (8.5 nm FWHM passband width), as the 495.9 nm OIII line is transmitted at only between 35% and 50%, while the other line comes through at over 90%. However, typically, the 495.9 nm OIII line is weaker than the 500.7 nm line, so the Baader filter still works fairly well. Clear skies to you.




David,
Thank You.
Excellant explanation and graphic.
I believe I now understand OIII filters much much better from when this thread was started.
These light filters act much the same as SSB and CW filters
Of course with these filters, in the newer rigs, you can vary them at will.
Wonder when the astro filters will become tunable, such as those in a few of the solar scopes ?

TNX
73, Rick - N8XI


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Starman1
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Re: OIII Filter Choice new [Re: rick-SeMI]
      #5438078 - 09/24/12 01:14 PM

One further note: the transmission bandwidth moves in the spectrum as the angle of light incidence changes. The light transmission FWHM figures are for light entering the filter perpendicular to the glass. The bottom and top wavelengths change slightly with small angle changes.
So if you are looking at an object 1 degree wide, the edges of the object do not see exactly the same "window" of wavelengths the center of the object does.
So:
--to examine details, bring the target to the center of the field

Some very inexpensive filters' housings can result in slight tilts in the glass in the housing. That will impact the bandpass.

Because these are basically interference filters, off-axis light may see a completely different spectrum of transmission. You can see that will some narrowband filters which appear blue-green when looking straight through, and pink when looking through at an oblique angle.

If you have a scope with a truly wide true field (like 4-5 degrees), this can actually have an impact on what you see in the field in different parts of the field.

This is a logical reason why the bandwidth of a filter has to be wider than the minimum necessary to be sure to transmit the desired wavelength everywhere in the field.
Otherwise, a 15nm bandpass could transmit H-Beta, and both O-III lines. But, most narrowband filters have bandpasses more like 25nm to be sure slight off-axis views won't get "clipped".


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Scanning4Comets
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Re: OIII Filter Choice new [Re: Starman1]
      #5650382 - 01/29/13 01:54 PM

After reflecting on this subject and owning the Celestron, (Baader OIII), and Lumicon OIII filters, I have come to the conclusion that the Lumicon is the way to go for the OIII filter of choice.

The Celestron / Baader OIII is indeed too dark at 8.5nm.

Cheers,


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photiost
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Re: OIII Filter Choice new [Re: David Knisely]
      #5657409 - 02/01/13 11:51 PM

Quote:



Here is a site that has some of the current OIII filters transmission curves:

http://www.astroamateur.de/filter/oiii.html

I still like the Lumicon OIII (if you can get one), but the DGM Optics OIII or Thousand Oaks OIII are pretty good as well. Clear skies to you.




I recently got the Burgess Optical (2in) OII filter as part of a deal. The previous owner could not tell me more than he bought it from Burgess about 4 yrs ago.

Any comments/info on this filter is appreciated.
.


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Scanning4Comets
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Re: OIII Filter Choice new [Re: photiost]
      #5680603 - 02/15/13 02:40 AM

My comment two above will now seem somewhat hypocritical because I just purchased yet "another" O-III filter like my last one. My last one was a Celestron and this one is a Baader O-III.

I wanted to try the Baader to see how much alike they really are! There was also a DGM O-III I just missed out on as well. David Knisely: What is the DGM O-III like?

Cheers,


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Ava
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Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5680672 - 02/15/13 04:32 AM

I have the DGM O-III filter, bought new around 6 months ago. Unfortunately skies have been pretty bad since october basically so I have not used it a lot under the stars. It does give good sharp views, it is certainly a lot narrower than my Astronomik UHC (that one is rather wide) and hightens contarast well for some objects. If I remember correctly, it should be a few nm wider than the Lumicon O-III (around 14-15nm).

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David Knisely
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Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5681562 - 02/15/13 01:52 PM

Quote:

My comment two above will now seem somewhat hypocritical because I just purchased yet "another" O-III filter like my last one. My last one was a Celestron and this one is a Baader O-III.

I wanted to try the Baader to see how much alike they really are! There was also a DGM O-III I just missed out on as well. David Knisely: What is the DGM O-III like?

Cheers,




The one I got for review here on Cloudynights is actually a tad wider than my Lumicon OIII:

CN REPORTS: DGM Optics OIII Filter

Otherwise, it works fairly well. Clear skies to you.


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Starman1
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Re: OIII Filter Choice new [Re: David Knisely]
      #5682052 - 02/15/13 05:48 PM

David,
Since you are still logged in to this thread, you might be interested in my notes from last Saturday night in which I viewed NGC2359, "Thor's helmet",
with both the Lumicon O-III and TeleVue O-III filters.

As you would expect, the narrower bandwidth of the Lumicon displayed more nebulosity--3 distinct "tails" away from the central bubble, striae within the bubble, and some 'clouds' away from the main body a bit. A very spectacular view of the nebula.

The TeleVue filter did not show the level of contrast--the background was lighter, and the 3rd extension from the central bubble was hard, and the outer 'cloud' of nebulosity wasn't seen.

BUT, the number of stars in the field of view with the TeleVue filter was similar to the non-filter view--very rich with stars.

Esthetically, I couldn't say which I preferred the most. The 12.5", under very dark skies (SQM21.7) showed a lot of stars in the field even with the Lumicon filter. But the overall impression of the field with the TeleVue filter was most impressive, even if the very faintest nebular details weren't as obvious. And the TeleVue also showed M46 and its associated planetary better than the Lumicon (the stars were a lot brighter).

Comparing a lot of filters recently on a number of nebulae, I'm coming to realize that there is room for different filters to be used on different objects.
M42, for instance, was far more colorful to me with a Baader UHC-S than with the Lumicon UHC. The red wavelengths transmitted and the slightly broader main passband of the Baader really matched well with that object.
On M27, though, the Lumicon was definitely preferred, revealing ropy tendrils in the outer nebulosity far better than the Baader.

I think it is up to guys like you and me to point out the bandwidth issues of the filters that are out there, but also to ask what it is the observer is hoping to accomplish. Not everyone is going to prefer exactly the same filter choice under all conditions and on all nebulae.


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Scanning4Comets
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Re: OIII Filter Choice new [Re: Starman1]
      #5682180 - 02/15/13 07:05 PM

What about this filter ? :

Omega O-III Nebular filter # 144918


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Starman1
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Re: OIII Filter Choice new [Re: Scanning4Comets]
      #5682253 - 02/15/13 07:56 PM

Markus,
I think David linked to a review of that very filter a couple posts ago.
DGM filters come from Omega.


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Jon Isaacs
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Re: OIII Filter Choice new [Re: Starman1]
      #5682263 - 02/15/13 08:03 PM

Quote:


I think it is up to guys like you and me to point out the bandwidth issues of the filters that are out there, but also to ask what it is the observer is hoping to accomplish. Not everyone is going to prefer exactly the same filter choice under all conditions and on all nebulae.




Don:

I use an O-III filter when I want to maximize the nebulosity, the Orion Ultrablock when I want to balance the nebulosity and the starfield. My one nighter with the TV O-III leads me to believe the TV filter is more of a UHC filter than an O-III filter.

Jon


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David Knisely
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Re: OIII Filter Choice new [Re: Jon Isaacs]
      #5682685 - 02/16/13 12:53 AM

Quote:

Quote:


I think it is up to guys like you and me to point out the bandwidth issues of the filters that are out there, but also to ask what it is the observer is hoping to accomplish. Not everyone is going to prefer exactly the same filter choice under all conditions and on all nebulae.




Don:

I use an O-III filter when I want to maximize the nebulosity, the Orion Ultrablock when I want to balance the nebulosity and the starfield. My one nighter with the TV O-III leads me to believe the TV filter is more of a UHC filter than an O-III filter.

Jon




The Tele Vue is a narrow-band filter in terms of raw FHWM bandwidth, but the location of that passband is centered on the OIII lines and not between the OIII and H-Beta lines as is done with a true narrow-band nebula filter. I still prefer the DGM NPB to the Tele Vue OIII, as it has a similar bandwidth, sharper edges, and, in addition to passing the OIII lines, lets through the H-Beta line at a high level of transmission rather than excluding it as the Bandmate "OIII" does. For a true Oxygen III nebula line filter, I would definitely prefer the Lumicon OIII or Thousand Oaks LP-3 OIII filter. Clear skies to you.


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David Knisely
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Re: OIII Filter Choice new [Re: Starman1]
      #5682707 - 02/16/13 01:17 AM

Quote:

David,
Since you are still logged in to this thread, you might be interested in my notes from last Saturday night in which I viewed NGC2359, "Thor's helmet",
with both the Lumicon O-III and TeleVue O-III filters.

As you would expect, the narrower bandwidth of the Lumicon displayed more nebulosity--3 distinct "tails" away from the central bubble, striae within the bubble, and some 'clouds' away from the main body a bit. A very spectacular view of the nebula.

The TeleVue filter did not show the level of contrast--the background was lighter, and the 3rd extension from the central bubble was hard, and the outer 'cloud' of nebulosity wasn't seen.

BUT, the number of stars in the field of view with the TeleVue filter was similar to the non-filter view--very rich with stars.

Esthetically, I couldn't say which I preferred the most. The 12.5", under very dark skies (SQM21.7) showed a lot of stars in the field even with the Lumicon filter. But the overall impression of the field with the TeleVue filter was most impressive, even if the very faintest nebular details weren't as obvious. And the TeleVue also showed M46 and its associated planetary better than the Lumicon (the stars were a lot brighter).

Comparing a lot of filters recently on a number of nebulae, I'm coming to realize that there is room for different filters to be used on different objects.
M42, for instance, was far more colorful to me with a Baader UHC-S than with the Lumicon UHC. The red wavelengths transmitted and the slightly broader main passband of the Baader really matched well with that object.
On M27, though, the Lumicon was definitely preferred, revealing ropy tendrils in the outer nebulosity far better than the Baader.

I think it is up to guys like you and me to point out the bandwidth issues of the filters that are out there, but also to ask what it is the observer is hoping to accomplish. Not everyone is going to prefer exactly the same filter choice under all conditions and on all nebulae.




If I want to see stars with a little nebulosity, I will use a good broad-band LPR filter like the Orion Skyglow. It is a tad narrower than the Lumicon Deep-sky and will provide a bit more contrast in emission nebulae without hurting the stars much at all. In fact, I prefer that filter for reflection nebulae like the Merope Nebula or the Iris Nebula. However, for emission nebulae, I want to see nebulosity and not just stars. For that, clearly, a narrower filter is needed. The Tele Vue OIII has the narrower passband (about 240 angstroms FWHM) but it isn't centered properly. Its transmission of the H-Beta line is only 28.8%, and the profile of the passband is more of a Gaussian form than something sharp. The DGM NPB has about the same FWHM passband width, so its effect on stars should be similar to that of the Tele Vue OIII. However, its transmission at both the OIII and H-Beta lines is around 94%, so it will enhance nebulosity that happens to have either a balance of OIII and H-Beta or just H-Beta. For my money, as a single purchase, the DGM NPB is a much more effective filter than the Tele Vue Bandmate OIII. In the case of true Oxygen III filters, stars are again not an issue. When making the choice to use an OIII filter, you are going after the maximum contrast, so you want a filter that lets through only the OIII lines and little else. Indeed, when under some skyglow, on some nebulae like the Dumbell, I will often switch to an OIII rather than use my narrow-band filters just to be able to see the object with more contrast. For that, again, the Tele Vue Bandmate OIII is an also-ran. It is just too much of a compromise in design. Clear skies to you.


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