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Old 17-04-2022, 05:38 PM
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pmrid (Peter)
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Filter choices for OSC imaging

Recently saw reviews of the Antlia dual band filter ( https://www.testar.com.au/products/a...SABEgJOa_D_BwE) at $599 from Testar and wondered how users had found it compared with other choices. With a 5nm bandpass in both OIII and Ha, the Antlia certainly seems like a good choice for mid-level light polluted areas such as mine.

But I have also read some interesting discussions about the effect of focal ratios on the bandpass shift issue. I will be imaging mainly at F5 or F6 so I expect the impact to be minor. But, I’d appreciate any suggestions for alternatives that are perhaps not so bloody expensive.
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Old 17-04-2022, 06:53 PM
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AstroJunk (Jonathan)
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I have the OPTOLONG L-eNhance for use at f2 and it works very nicely. The L-eXtreme is too narrow and the Ha drops off entirely at hyperstar f-ratios. Being Tri-band, it really maximises the potential of our OSCs.

The attached photo is a test image under a 1st quarter moon which is pretty good all things considered - has no significant processing.
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  #3  
Old 17-04-2022, 10:07 PM
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Originally Posted by AstroJunk View Post
I have the OPTOLONG L-eNhance for use at f2 and it works very nicely. The L-eXtreme is too narrow and the Ha drops off entirely at hyperstar f-ratios. Being Tri-band, it really maximises the potential of our OSCs.

The attached photo is a test image under a 1st quarter moon which is pretty good all things considered - has no significant processing.
Hi Jonathan. What got me started was the YouTube video by Cuiv ďThe lazy geekĒ entitled ďOSC Narrowband filters - what to buyĒ and in particular the graphs and explanations starting around the 8 minute mark explaining how much signal is lost at very short focal ratios. I found it very interesting and it got me started in wondering about filters with very narrow bandpass.
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Old 18-04-2022, 09:20 AM
Startrek (Martin)
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I use my L Extreme ( 7nm Ha Oiii ) with a 2600MC at both f5 and f6 under Bortle 8 Suburban and Bortle 3 dark site when moon is around and itís a game changer
Started with a ZWO Duoband a few years back for a while but the L Extreme blew my socks off

Cheers
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  #5  
Old 18-04-2022, 09:41 AM
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Originally Posted by Startrek View Post
I use my L Extreme ( 7nm Ha Oiii ) with a 2600MC at both f5 and f6 under Bortle 8 Suburban and Bortle 3 dark site when moon is around and it’s a game changer
Started with a ZWO Duoband a few years back for a while but the L Extreme blew my socks off

Cheers
Yes. The ZWO duo is a bit of a dud. With bandpass of a whopping 35nm in the OII/Hbeta) and 15nm in Ha, it does not give me the contrast I want. I have bitten the bullet (late last night) and ordered a L-Enhance with figures of ~25 (OIII and H-Beta) and ~11 (Ha) it’s not down there with the “Extreme” I admit but it will have to do.

Last edited by pmrid; 18-04-2022 at 08:26 PM.
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  #6  
Old 18-04-2022, 09:57 AM
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I have the Antila dual-band filter (but have so far only managed to use it once due to the terrible weather in recent times).

One of things that attracted me was the claimed halo suppression around bright stars which seems to be a problem with filters containing tight OIII bands. Whether that holds true remains to be seen along with the claimed performance at low f-ratios.

I'm still new to processing these types of images but here are a couple of renditions of my first light with the filter. About 1.8 hours of exposure in Bortle 7 skies at f5.3.
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  #7  
Old 18-04-2022, 10:09 AM
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Quote:
Originally Posted by Retrograde View Post
I have the Antila dual-band filter (but have so far only managed to use it once due to the terrible weather in recent times).

One of things that attracted me was the claimed halo suppression around bright stars which seems to be a problem with filters containing tight OIII bands. Whether that holds true remains to be seen along with the claimed performance at low f-ratios.

I'm still new to processing these types of images but here are a couple of renditions of my first light with the filter. About 1.8 hours of exposure in Bortle 7 skies at f5.3.
Iíd love to see comparison shots with the L-Extreme and the Antlia - the 5nm version at least. The reviews of the Antlia are certainly glowing. Pity about the price!
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  #8  
Old 18-04-2022, 07:57 PM
Startrek (Martin)
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Images from last night with L Extreme under full moon in Bortle 3 skies
8Ē f5 GSO Newt
About 2 hrs of data
Iím super happy with the L Extreme and obviously donít suffer from Star halos with the newt , so I canít see myself upgrading to the ďGoldenĒ Antlia Duoband
I donít think the slightly tighter bandpass will accentuate the detail my images from what the L Extreme is capable of doing at present.

Cheers
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  #9  
Old 19-04-2022, 02:51 AM
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Thanks Martin. With the images posted by Pete - of the same object but with an Antlia filter, I have the comparison I wanted. And thanks to Pete also, of course.

I will enjoy spending time with these.
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  #10  
Old 19-04-2022, 09:15 AM
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L-eNhance, Bortle 4, 98% Moon last night
110mins Esprit 100/ASI071 live stacked using the ASI Air

Stretched only - I've made no colour changes so you can see exactly what comes off the camera. It does the job pretty well I recon, I should have done some darks...
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  #11  
Old 19-04-2022, 01:11 PM
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Quote:
Originally Posted by AstroJunk View Post
L-eNhance, Bortle 4, 98% Moon last night
110mins Esprit 100/ASI071 live stacked using the ASI Air

Stretched only - I've made no colour changes so you can see exactly what comes off the camera. It does the job pretty well I recon, I should have done some darks...
Great Jonathan! That completes the trifecta of filters.
My l-eNhance is still in transit. Iím extra keen to get it into action.
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  #12  
Old 19-04-2022, 01:47 PM
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Quote:
Originally Posted by Retrograde View Post
I have the Antila dual-band filter (but have so far only managed to use it once due to the terrible weather in recent times).

One of things that attracted me was the claimed halo suppression around bright stars which seems to be a problem with filters containing tight OIII bands. Whether that holds true remains to be seen along with the claimed performance at low f-ratios.

I'm still new to processing these types of images but here are a couple of renditions of my first light with the filter. About 1.8 hours of exposure in Bortle 7 skies at f5.3.
That second image is a cracker
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  #13  
Old 19-04-2022, 02:38 PM
Dave882 (David)
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The l-extreme is very useful when imaging Ha or Oiii rich targets and very effective countering the effects of full moonshine and city light glow. Iíve used it extensively with my scts at both native focal lengths and reduced to f7, f6.3 and f1.9 with the Hyperstar.

With regards to using l-extreme with the Hyperstar, Iíve never done the calcs but am persuaded by others that there is a substantial loss in effective aperture. However, that doesnít mean itís not still effective and it can still deliver good contrast with severe light pollution. Just need to be aware of the trade offs. Iíve recently purchased a dual band IDAS NBZ filter which is pre shifted for use with Hyperstar. Just havenít had a good night to trial it yet.

In addition I like using the Optolong UHC filter to reduce light pollution and this fairly versatile for a variety of targets.
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Old 19-04-2022, 04:43 PM
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Here's the Tarantula with the L-eXtreme at f2 and its isolated red channel. It's fair to say that this is largely an OIII object anyway, but the loss of Ha was more dramatic than I had expected.
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Old 20-04-2022, 02:45 PM
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That second image is a cracker
Thanks Nik! That was actually my first processing attempt which I did by following a YouTube tutorial.

Nice pics everyone. Clearly on the subject of multi-narrowband filters it's horses for courses, depending on your scope type etc.

I also have an Optolong L-Pro for broadband objects but I'm not convinced it's that worthwhile. Whilst it reduces LP & associated gradients it still leaves some that need to be fixed in post-processing anyway, & affects the colour balance a bit (although less than most other comparable filters. It would mainly help to allow longer length subs without the sky background overwhelming the signal.
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Old 21-04-2022, 04:50 PM
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Here's the Tarantula with the L-eXtreme at f2 and its isolated red channel. It's fair to say that this is largely an OIII object anyway, but the loss of Ha was more dramatic than I had expected.
I’m afraid I have to disagree with you on this. The Tarantula is the largest EMISSION nebula known which makes it a major Ha source. So your loss of Ha signal has been almost entire. Can I suggest you have a look at the YouTube video I referenced earlier. I found it a very interesting discussion and explanation for the phenomenon you are experiencing.

Last edited by pmrid; 22-04-2022 at 08:00 AM.
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Old 03-05-2022, 06:58 AM
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Hi Peter - I've been using the 2" Antlia Dual Band 'Golden' filter with my 2600MC.


This gear marks a return to imaging after a 10 year drought, so I'm in no position to give anything but rookie opinions.


I'm enjoying the images from this filter - I attach recent Eta and Tarantula pics(please excuse processing and significant tilt issues at edges - yet to fix)
Eta is 26x600s and Tarantula 18x600s


Stars have slight blue haloing, but that's more likely an artifact from my dodgy PS skills.


I may be putting this filter up for sale soon though as I got the dreaded oil leak on the 2600MC sensor - ZWO will replace, but I'm using the 'opportunity' to move to the 2600MM sensor and therefore the OSC accessories will be for sale (all going well)


Cheers
Doug
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  #18  
Old 03-05-2022, 11:46 AM
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Originally Posted by dugnsuz View Post
Stars have slight blue haloing, but that's more likely an artifact from my dodgy PS skills.
It's pretty common with this filter, at least with refractors.

Quote:
Originally Posted by dugnsuz View Post
I may be putting this filter up for sale soon though as I got the dreaded oil leak on the 2600MC sensor - ZWO will replace, but I'm using the 'opportunity' to move to the 2600MM sensor and therefore the OSC accessories will be for sale (all going well)


Cheers
Doug
ha, same. I bought the QHY because of an oil leak on the 2600MC. Mine's all cleaned up now, but still... didn't give me a lot of confidence. The MM can have it as well.
I'm almost hoping it happens again so I can get it replaced by ZWO. When I had it happen to me, it was before ZWO said they'd replace the cameras, and Testar cleaned it for me instead.
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Old 03-05-2022, 07:58 PM
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Thankfully my oil leak wasnít as bad as some Iíve seen - slowly creeping towards sensor!!
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  #20  
Old 04-05-2022, 11:03 AM
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Lucky. Mine was worse than that!
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