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Optolong L-eXtreme filter comparison

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#1 jimthompson

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Posted 01 September 2020 - 09:16 AM

Hi Group,

 

Optolong released a new filter this past June called the L-eXtreme.  It is a dual narrowband filter, passing the O-III and Halpha emission lines from nebulae.  I purchased a sample to test against a range of other light pollution filters sold by Optolong.  The results are summarized in the test report linked below.  In a nutshell, the filter works very well at increasing the contrast of emission type nebulae.  I found it easier to white balance the live view than some other similar filters such as Optolong's L-eNhance filter.  The trade off for the improved contrast is a need for increased exposure time.

 

http://karmalimbo.co...ter_Aug2020.pdf

 

Cheers,

 

Jim T.


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#2 JMW

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Posted 01 September 2020 - 11:04 AM

Thanks for this. I plan on buying the L-eXtreme when it becomes available again. It seems to be back ordered at the places I looked.



#3 jimthompson

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Posted 01 September 2020 - 12:12 PM

Your welcome Jeff.  I had the filter on pre-order at AgenaAstro.com back in May, so I got one from the first shipment they received from Optolong at the end of June.  I think the filter will be a strong seller as it performs well and is competitively priced.

 

Cheers,

 

Jim T.



#4 SoDaKAstroNut

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Posted 01 September 2020 - 12:40 PM

Some CN'ers (not in this thread) keep posting that the L-eXtreme "let's more [OIII] through than the L-eNhance." In my brief experience, the opposite is true - narrower bandwidth (7nm for L-eXtreme vs 24nm for L-eNhance) constricts the amount of [OIII] and Ha that gets to your camera's sensor.

 

Note the increased amount of blues, including stars, in the L-eNhance in Jim T's attachment. The cost is there is less contrast in the L-eNhance because the amount of spurious light washes out the image. The restricted bandwidth of the L-eXtreme reduces the background stars, and some nebulosity if not enough data is captured, and gives the visual effect that the photons that do get through the filter have higher contrast. Light is a spectrum not a bunch of spikes.

 

IMHO, if you have extreme LP and/or want to sacrifice some delicate nebulosity for increased, specific structure detail, then L-eXtreme is your choice. If you have moderate LP and/or want a slightly broader spectrum of nebulosity, then get the L-eNhance.

 

Like most things astronomical/AP it's not "X is better than Y", these are just tools that each have their purpose. There may be some overlap.

 

Also from a business perspective, why would Optolong release one product that makes their other very popular product obsolete? Doesn't make smart business sense.

 

Thank's to you Jim for the excellent write-up.

 

CS & GB!


Edited by SoDaKAstroNut, 01 September 2020 - 12:41 PM.

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#5 JMW

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Posted 01 September 2020 - 12:53 PM

I live less than a mile from so very bright urban light pollution. (Reno casinos)  I have been getting good results with a 7nm Ha filter. I like the idea of using the L-eXtreme so I can enjoy some imaging with Ha and OIII when doing it in my backyard. I pick my targets closer to the zenith when possible to reduce the affects of light pollution. I have a SBIC STF8300m Pro Plus mono setup with 7 filters but my limited horizons at home make it very tedious to get enough hours on a target with each filter. The ASI2600MC Pro makes it so much easier to get enough useful data on a target in a limited amount of time.

 

When I go to dark sites I prefer to do normal spectrum OSC with the camera to take advantage of the dark skies and limited time at the dark site.

 

I can enjoy normal spectrum OSC at my home for EAA as long as the moon isn't up. Under moon light the Ha filter gives me a way to enjoy the light polluted sky. I also have a white phosphor PVS14 that I use in light polluted and dark sites to improve the number of targets to be enjoyed.

 

I think there is a decent use case for both filters and of course slightly different price points. 


Edited by JMW, 01 September 2020 - 12:56 PM.

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#6 SoDaKAstroNut

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Posted 01 September 2020 - 01:06 PM

I also have a white phosphor PVS14 that I use in light polluted and dark sites to improve the number of targets to be enjoyed.

Excellent idea. I have a astronomy club co-member who is very well versed in using his PVS on his Dob and setting circles to locate any available target in the sky. He can see even the faintest, delicate nebs. He has a channel on YouTube - see Dakota Starry Nights.

 

CS & GB!



#7 jimthompson

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Posted 01 September 2020 - 01:44 PM

A big challenge I had when doing this testing using a OSC camera was dealing with the white balancing.  The way in which I did this step had a huge influence on the appearance of the final image, especially with regards to the relative prominence of O-III and Halpha emissions.  I gave up on trying to get a good consistent white balance within the capture software and limited myself to doing it in post processing, at least when I was trying to do a visual comparison between filters.  In this recent test I came up with a rather complicated multi-step method that ensured that all the images were white balanced the same, a pain in the butt really.  In this testing as well as all the work I did earlier in the year with multi-narrowband filters* I found that filters with a passband that includes both Hbeta and O-III along with a narrow Halpha pass band tend to be very heavily weighted on the green channel of OSC cameras.  Most of the transmission of the filter is at the same wavelength as the camera sensor's peak sensitivity, plus OSC cameras have 2 green pixels for every red or blue pixel.  For the user to then white balance this very green image they have to heavily suppress the green channel in the image which in turn upsets the natural balance between O-III and Halpha emissions.  This is why some people find the L-eNhance filter lets through less O-III than the L-eXtreme; because to get a proper white balance you have to suppress the green channel much more with the L-eNhance than you do with the L-eXtreme.

 

As for why Optolong would come out with the L-eXtreme just a year or so after the L-eNhance, making the later redundant, who can say.  If you have followed Optolong at all you will have recognized that they are trying to follow as close as possible the trends in the market.  When one company comes out with a new filter, they come out with a competing product shortly afterwards.  This new filter is a direct competitor of the OPT Radian Ultra both in performance and price.  I think they have set their pricing more based on market pressure than on what the actual manufacturing costs are.  So although the L-eXtreme provides better performance than the L-eNhance, there are still people who are not willing to pay $300 for a filter but they will pay $200.

 

Cheers,

 

Jim T.

 

 

http://karmalimbo.co...ers_Feb2020.pdf


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#8 Astrojedi

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Posted 01 September 2020 - 02:16 PM

I can summarize the difference in a couple of points: L-enhance and L-extreme produce very similar HA channels but the L-enhance has a wider OIII channel. Due to the wider OIII channel the L-enhance produces a slightly brighter background and more stars in the image.

 

Having said that L-enhance has produced very good results for my from my Red/White LP zone backyard. I actually like the more natural looking stars in the L-enhance data. L-extreme is a true dual narrowband filter.

 

If imaging at a darker site (bortle 6 or better) I would prefer the L-enhance over the L-extreme. 


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#9 Paul Garais

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Posted 01 September 2020 - 02:40 PM

I life in a Bortle 4 (maybe on it's way to Bortle 5) zone. For me the L-enhance is not of much use, because I do not need to fight light pollution. All I have to do is to get more subs. And for extremely faint emission nebulae details, the L-enhance has to broad "openings" to give me an advantage.

But the L-eXtreme gives me the option to image in moonlight. Putting galaxy season aside, I can almost go out imaging for as twice as many nights as before without wasting my time.

For extremely faint details and for imaging in moonlight (or strong light pollution), the L-eXtreme has definitly an advantage compared to L-enhance.
So from a marketing perspective: Optolong gets customers, that they could not attract before. Nothing stupid about that.


—Paul

#10 jimthompson

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Posted 01 September 2020 - 02:51 PM

Indeed the L-eNhance provides more visible stars than the L-eXtreme.  There is a side effect of this:  live stacking algorithms can have more difficulty when using the L-eXtreme, especially when observing objects low on the horizon.

 

I am not sure I would agree that the stars look more "natural" with the L-eNhance filter.  There are certainly more stars visible, but their colours are not anywhere near correct when using this filter.  If you white balance by aligning the peak of each colour channel's histogram, you get a nice grey/black background but the stars are not the correct colour.  They have a bluish-green hue when using the L-eNhance.

 

Cheers,

 

Jim T.


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#11 jimthompson

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Posted 01 September 2020 - 02:57 PM

"I life in a Bortle 4 (maybe on it's way to Bortle 5) zone. For me the L-enhance is not of much use, because I do not need to fight light pollution. All I have to do is to get more subs. And for extremely faint emission nebulae details, the L-enhance has to broad "openings" to give me an advantage."

—Paul

Hi Paul,

 

It is a common misconception that a light pollution filter is needed only if you have a light polluted sky.  In reality adding a light pollution filter will improve the contrast of emission-type nebulae regardless of how much light pollution you have.  This is because only some of the light pollution we encounter is man-made.  There is also a significant amount of light pollution coming from sky glow and other natural sources.  LP filters help to reduce naturally occurring LP as well.

 

Cheers,

 

Jim T.


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#12 Paul Garais

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Posted 01 September 2020 - 03:04 PM



Hi Paul,

It is a common misconception that a light pollution filter is needed only if you have a light polluted sky. In reality adding a light pollution filter will improve the contrast of emission-type nebulae regardless of how much light pollution you have. This is because only some of the light pollution we encounter is man-made. There is also a significant amount of light pollution coming from sky glow and other natural sources. LP filters help to reduce naturally occurring LP as well.

Cheers,

Jim T.


Hi Jim,

thank you for the input. I understand the concept. The reason I consider the L-enhance as not as useful as the L-eXtreme for my situation, is because the advantage the L-enhance gives for my situation is not significant enough. This is the reason, why I wrote, I can just go for more integration time (instead of getting the L-enhance).
I did not wanted to say that it is completely useless or has no effect. It is just not as eXtreme ;).

—Paul

#13 Astrojedi

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Posted 02 September 2020 - 09:59 AM

Paul,
Even the L-enhance should significantly enhance the contrast of nebulae from your dark skies. I see a big difference with and without when imaging from my club’s dark site which is very similar to your location.

 

Keep in mind sources of ‘light pollution’ are not just artificial lights but any unwanted signal.


Edited by Astrojedi, 02 September 2020 - 10:01 AM.

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#14 Paul Garais

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Posted 02 September 2020 - 10:19 AM

I talked about differences and btw also mentioned moonlight, which is obviously not artificial. There is a difference between L-enhance and L-eXtreme no matter how often you correct a claim I did not make.

I did not say that the L-enhance has no effect. I also did not neglect the existence of natural light sources.

#15 Astrojedi

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Posted 02 September 2020 - 10:38 AM

Ok I was just commenting on your statement that you did not see a significant difference with L-enhance. I was saying that I saw a pretty significant difference. Keep in mind that the H-alpha channel is pretty similar between both filters. The key difference is the narrower OIII channel. Most of the detail & resolution comes from the H-alpha channel.



#16 Astrojedi

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Posted 02 September 2020 - 10:40 AM

Indeed the L-eNhance provides more visible stars than the L-eXtreme.  There is a side effect of this:  live stacking algorithms can have more difficulty when using the L-eXtreme, especially when observing objects low on the horizon.

 

I am not sure I would agree that the stars look more "natural" with the L-eNhance filter.  There are certainly more stars visible, but their colours are not anywhere near correct when using this filter.  If you white balance by aligning the peak of each colour channel's histogram, you get a nice grey/black background but the stars are not the correct colour.  They have a bluish-green hue when using the L-eNhance.

 

Cheers,

 

Jim T.

I meant the image looks more natural with more stars (not that the stars look more natural).


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#17 Paul Garais

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Posted 02 September 2020 - 11:05 AM

Ok I was just commenting on your statement that you did not see a significant difference with L-enhance. I was saying that I saw a pretty significant difference. Keep in mind that the H-alpha channel is pretty similar between both filters. The key difference is the narrower OIII channel. Most of the detail & resolution comes from the H-alpha channel.

Nope, that is also not, what I said. No statement from me, that says "not see a significant difference".

Maybe a language problem on my side, since English is my third language. But I read my post again and do not see such a statement. If I am wrong, I would be happy about it to learn English. I have to admit, that it is influenced way too much by YouTube, English articles and discussion boards. Not the best sources to learn a language ;)


—Paul

#18 SoDaKAstroNut

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Posted 02 September 2020 - 12:14 PM

Light is a spectrum not a bunch of spikes.

After further thought I must correct my inaccurate comment. Filters are based on Kirchhoff's Laws - with the correct equipment spectral lines are displayed based on the chemical makeup of an object. See NASA's recent Hubble Program "Sailing Across the Local Universe with ULLYSES" for an excellent briefing on how spectroscopy is used to research young blue stars.


Edited by SoDaKAstroNut, 02 September 2020 - 12:45 PM.


#19 Astrojedi

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Posted 02 September 2020 - 12:29 PM

Nope, that is also not, what I said. No statement from me, that says "not see a significant difference".

Maybe a language problem on my side, since English is my third language. But I read my post again and do not see such a statement. If I am wrong, I would be happy about it to learn English. I have to admit, that it is influenced way too much by YouTube, English articles and discussion boards. Not the best sources to learn a language wink.gif


—Paul

:) no worries... Let me try again... I think what you are saying is that the L-enhance does not offer enough of an advantage over unfiltered from your dark skies hence you just prefer unfiltered with more exposure time. Whereas the L-extreme being a true narrowband filter provides a much bigger contrast enhancement.

 

If so, this is only partially true. This is because the band pass of H-alpha is very similar between the 2 filters. They both will produce almost the same definition and detail in the H-Alpha channel which is the primary channel that contributes to detail and definition of the nebula.

 

This is why I am confused with your statement.


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#20 Astrojedi

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Posted 02 September 2020 - 12:44 PM

Here is a stack of the H-alpha channel of the L-enhance filter of the Lagoon nebula. Taken from my red/white zone skies with the RASA 8, ASI533MC and Optolong L-enhance. It is almost impossible for me tell this apart from my 7nm HA filter results.

 

Even if you have dark skies you cannot reproduce such definition and detail without a narrowband filter. This is why I believe the L-enhance will always be superior to unfiltered imaging even from dark skies.

 

Note: This is not EAA but I have posted this purely to inform this discussion. Mods please let me know if there is an issue.

 

See image of Lagoon HA extract stack here: https://www.cloudyni...oon-ha-extract/

 

(Image moved to gallery as per the Mod's request)


Edited by Astrojedi, 02 September 2020 - 03:57 PM.

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#21 Paul Garais

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Posted 02 September 2020 - 12:44 PM

Thank you for taking the time looking into it! I see where my post is poorly written now. What I meant to say is, that the L-eXtreme gives an advantage over the L-enhance, especially in moonlight.

I should have clearly uncoupled the integration time part from that.

#22 Astrojedi

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Posted 02 September 2020 - 12:49 PM

Thank you for taking the time looking into it! I see where my post is poorly written now. What I meant to say is, that the L-eXtreme gives an advantage over the L-enhance, especially in moonlight.

I should have clearly uncoupled the integration time part from that.

Yes, I would agree with that. The narrower OIII channel of the L-extreme helps with that.



#23 jimthompson

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Posted 02 September 2020 - 12:52 PM

Not sure I've ever said this before ... I agree with Hiten. grin.gif   The step increase in contrast of Halpha based emission nebulae, going from no filter to the L-eNhance, is significant.  The increase in contrast is roughly 2/3rds of the contrast increase you would see going from no filter to the L-eXtreme.

 

That said, we all have different objectives to our observing as well as different conditions and equipment.  There is no right or wrong in my mind.  I just hope that the information I put out there helps people to maximize their enjoyment of the hobby.

 

Cheers,

 

Jim T.



#24 mic1970

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Posted 02 September 2020 - 12:56 PM

Jim.... Do you have a similar comparisons (pics) with galaxies?  I'm learning and would like to see them.  



#25 Astrojedi

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Posted 02 September 2020 - 12:57 PM

Not sure I've ever said this before ... I agree with Hiten. grin.gif  

Haha... the sun did not rise in the east today :)




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