Optolong Filter

[Geoff Barnes]

I have recently ordered one of these H-Beta filters in my pursuit of the elusive Horsehead.

Does anyone have experience with these filters or this company's products?

They are certainly a lot cheaper than many competitors and seem to use high quality materials.

"Optolong H-Beta 25nm Filter - 1.25”

This Optolong H-Beta filter has a FWHM of 25nm, making it more suitable for visual observations of the Horsehead, California, and Cocoon nebulae. The filter transmits a 25nm bandwidth of light that is centered at 486nm and precision blocks other transmissions, including wavelengths of light that are responsible for light pollution (both artificial and natural). When you use the 25nm H-Beta filter, you’ll notice that the contrast between the background sky and objects that emit H-Beta light increases. This allows you to see these elusive objects more easily, but you will still need a telescope with an aperture of at least 8” and a night of good seeing.

The Optolong 1.25” H-Beta 25nm Filter is made with Schott glass that has been multi-coated with an ion-assisted deposition technology to ensure scratch resistance and stability on the central wavelength, or CWL. The filter cell is made of lightweight, strong metal and is CNC machined, sand-blasted, black anodized, and then laser engraved. The result is a super thin filter cell that will produce a clear aperture of 26mm.

Quality Filter Materials:

Schott B260 substrate material from Germany, 2.0mm thick

CNC machined and black anodized aero-metal filter cell that is ultra-thin to provide largest clear aperture; Laser-engraved to prevent fading

Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with Ion-assisted deposition

Optolong Filter Manufacturing Processes and Parameters

Filter substrate is fine-optically polished to 1/4 wave and <30 parallelism over both surfaces

Surface quality, according to MIL-O-13830, is 60/40

90% transmission at H-Beta 486nm

0.1% transmission Hg at 435nm and 578nm

0.1% transmission Na at 589nm

High value transmission of pass-band and optical density of off-band is assured through Optolong’s planetary rotation system, a homogenous and precise coating procedure

Thin metal cells have a clear aperture of 26mm for 1.25” filters

Each filter comes with a plastic case with high pressure EVA case lining

About Optolong

Optolong is the Astronomy Filters division of Yulong Optics, an optical filter design and processing company out of Kunming, China that has provided filters for over 700 optical companies since 1999. All Optolong filters pass European Union RoHS requirements and have been certified by TUV Rheinland and Bureau Veritas."

 

[John]

I've tried a few low cost narrow band and line filters out Geoff and to be honest, they just have not really measured up. I had a Optolong UHC for a short while and it had practically no effect. When I stuck my NBP filter back in (a UHC from Omega) the difference was quite stark.

 

[Louis D]

Interesting read about Optolong on Astronomik's website.

[jetstream]

9 hours ago, Geoff Barnes said:

About Optolong

Avoid them IMHO.

Buy an Astronomik.

[Geoff Barnes]

It's interesting isn't it? I bought an Astronomic UHC a while ago expecting great results and I have to say I am completely underwhelmed by its performance. I've been using it a lot on nebulas such as Orion, Carina, the Magellanic Clouds to name a few during nights of really good seeing and I have to say in all cases I preferred the unfiltered views.

Now it may well be just my particular eyesight is a bit strange, I don't know, but in my 12 inch Dob I just love the bright sharp unfiltered views it gives me, the UHC just seems to dim and mute everything.

Due to very limited funds I'm always looking to save as much as possible when buying astro equipment so I was somewhat annoyed after paying Astronomik prices to be disappointed with it.

I will be very interested to see how the Optolong filter performs when it arrives and will of course post my opinions in due course. ?

[jetstream]

40 minutes ago, Geoff Barnes said:

It's interesting isn't it? I bought an Astronomic UHC a while ago expecting great results and I have to say I am completely underwhelmed by its performance. I've been using it a lot on nebulas such as Orion, Carina, the Magellanic Clouds to name a few during nights of really good seeing and I have to say in all cases I preferred the unfiltered views.

Now it may well be just my particular eyesight is a bit strange, I don't know, but in my 12 inch Dob I just love the bright sharp unfiltered views it gives me, the UHC just seems to dim and mute everything.

Due to very limited funds I'm always looking to save as much as possible when buying astro equipment so I was somewhat annoyed after paying Astronomik prices to be disappointed with it.

I will be very interested to see how the Optolong filter performs when it arrives and will of course post my opinions in due course. ?

Sorry to hear about the Astronomik UHC- they are a tight UHC- what eyepieces have you tried it with?

Earlier Astronomik filters were a bit wider (more light) than Lumicon with the newer ones tighter.

From Vogels site

http://www.reinervogel.net/index_e.html

I'm sure Astronomik would replace a defective filter, but these things really do need dark skies and optimum exit pupils to work properly.

 

[Paul73]

Interesting. I agree wholeheartedly about narrow UHC’s, but......

What do you want to use it for? If you want general nice nebula views with the nebula “lifted” a bit, then you need broad. If you are wanting to tease out every last speck of nebulousity? Then narrow.

Try at low power to reduce the aggressiveness of the dimming.

Paul

PS. Yes. Astonomik are £££. 

[Paul73]

Sorry to the OP. Answered theUHC post. This is an Hb thread. Haven’t tried the Oblong brand, but can report that there isn’t much to choose between the Astronomik and Lumicon versions (bought both when obsessed with Horsey hunting last winter!).

Paul

[Geoff Barnes]

Thanks Gerry and Paul

I have mostly used the UHC with my Baader Mk1V zoom, and found through trial and error that it worked best at 24mm FL on nebulas, but still I preferred the unfiltered view.

I have a Skywatcher 32mm plossl on order which should arrive any day, I will most certainly give that a good testing with both the UHC and the H-Beta in due course!

[John]

If I had to live with just one deep sky filter it would be an O-III rather than a UHC. I've owned a few of both and consistently I find myself reaching for the O-III filters because they make such an impact.

For a couple of years an Astronomik O-III was my only filter with scopes from 4" to 10" in aperture and I didn't really miss the UHC at all. I have all 3 types now (Lumicon O-III, DGM NBP (UHC type) and an Astronomik H-Beta but the O-III is still the most used by some way.

I generally prefer unfiltered views as well but there are a number of targets where the O-III really makes a significant difference and some of those (eg: the Veil Nebula) are my most favourite DSO's now because of the impact of the O-III. The H-Beta has enabled me to see (well, glimpse) the Horsehead so thats covered it's cost already in my book.

 

[Geoff Barnes]

I agonised over wether to go for a UHC or O-III after reading so many opinions, maybe I made the wrong choice?

I am very keen to see the Veil, but I'm pretty sure it only just gets above our horizon for a brief period in winter.

It is up now, but alas it is the middle  of the day here! ?

[John]

Dark, cloudy and rainy here Geoff

Hope the current Oz heatwave is survivable for you.

[Geoff Barnes]

21 minutes ago, John said:

Dark, cloudy and rainy here Geoff

Hope the current Oz heatwave is survivable for you.

I can just about survive the heat, horrid though it is. Just got to hope no bushfires break out, everything is tinder dry now and ready to burn! ?

[Ricochet]

12 hours ago, Geoff Barnes said:

I have mostly used the UHC with my Baader Mk1V zoom, and found through trial and error that it worked best at 24mm FL on nebulas, but still I preferred the unfiltered view.

For an f5 telescope would have thought that the optimum would be at a shorter focal length than that, perhaps around 15mm. What focal length setting do you use for unfiltered views?

[Geoff Barnes]

4 hours ago, Ricochet said:

For an f5 telescope would have thought that the optimum would be at a shorter focal length than that, perhaps around 15mm. What focal length setting do you use for unfiltered views?

To be honest when I'm using the zoom I'm not concentrating on the FL much at all, I'm really just adjusting to whatever view I find best on any particular target. Quite often I find that I prefer the 24mm setting, especially for nebulas, which allows me to fit all of the target in the FOV  rather than just a portion of it. 

[Ricochet]

5 hours ago, Geoff Barnes said:

To be honest when I'm using the zoom I'm not concentrating on the FL much at all, I'm really just adjusting to whatever view I find best on any particular target. Quite often I find that I prefer the 24mm setting, especially for nebulas, which allows me to fit all of the target in the FOV  rather than just a portion of it. 

If FoV is the issue perhaps you need to consider wider AFoV eyepieces. My 14mm XW has about the same FoV as a zoom on the 24mm setting. 

[Geoff Barnes]

I quite agree! 32 mm plossl due to arrive any day! ?

[Don Pensack]

For a good performing H-ß filter, I recommend 9-12nm bandwidth, with >90% transmission.

So far, in my lab tests, the ones that have lived up to that so far are:

Astronomik H-ß (2017-2019)

TeleVue BandMate II H-ß (2018-2019)

Orion (US) H-ß (2018)

An older (2009) Lumicon H-ß

And no others.  Most of the others I've tested did not reach the 90% transmission point or were too wide (yielding poorer contrast).

You can check out some results of tests here:

https://searchlight.semrock.com/?sid=a08a1af9-84ee-49d2-959d-153d7e7c0eb8

[Geoff Barnes]

Thanks for that info Don, very enlightening!

I've tried the Optolong H-B filter a couple of times now on the Horse Head without the slightest hint of any nebulosity from IC 434.

Whilst I'm tempted to get an Astronomik H-B, I do wonder if my Bortle 4-5 Skies are ever going to be dark enough for me to have success.

[TheLookingGlass]

On 18/01/2019 at 20:56, Geoff Barnes said:

I agonised over wether to go for a UHC or O-III after reading so many opinions, maybe I made the wrong choice?

I am very keen to see the Veil, but I'm pretty sure it only just gets above our horizon for a brief period in winter.

It is up now, but alas it is the middle  of the day here! ?

You will def need the O-III for The Veil. The newer Astronomik O-III has a tighter bandpass than the older one they made. I have looked through one, and IMO it is amazing.

[John]

3 hours ago, TheLookingGlass said:

You will def need the O-III for The Veil. The newer Astronomik O-III has a tighter bandpass than the older one they made. I have looked through one, and IMO it is amazing.

A decent UHC will also show the Veil quite well. I first saw it with a 100mm refractor and a Baader UHC-S which is quite a "mild" UHC filter. An O-III does show it a lot more intensely though, I agree.

[TheLookingGlass]

On 14/02/2019 at 07:45, John said:

A decent UHC will also show the Veil quite well. I first saw it with a 100mm refractor and a Baader UHC-S which is quite a "mild" UHC filter. An O-III does show it a lot more intensely though, I agree.

The Baader UHC-S is more like a broadband filter. Your skies must be amazing, and very dark !!!  I tried viewing it in fairly dark skies using an Orion Ultrablock and it was "there", but not as detailed as when using the OIII, as you said.

Cheers!  :^)

[John]

1 hour ago, TheLookingGlass said:

The Baader UHC-S is more like a broadband filter. Your skies must be amazing, and very dark !!!  I tried viewing it in fairly dark skies using an Orion Ultrablock and it was "there", but not as detailed as when using the OIII, as you said.

Cheers!  :^)

I agree with all of this. The Baader UHC-S was the 1st "nebula" filter that I tried so was part of my learning curve. It did show me the Veil but my subsequent views with "full" UHC filters and especially O-III's have far surpassed it.