246 replies to this topic

[andysea]

This old thread just popped up so I thought I would post an image with a recently purchased Optolong 7nm H-alpha filter.

This was taken using my Moravian 16200 and Tak FSQ106+reducer. There are obvious halos but its not bad for a $120 filter, used from my house in the city.

Attached Thumbnails

• 

[jimthompson]

Hi G,

 

I suspect the way you are using the filter, in front of the objective lens, is why you are not seeing great performance.  These filters are all designed to give the best performance when light is all going through it at right angles.  As the light angles further and further from a right angle, the pass band of the filter will widen and shift towards blue, affecting its performance.  For a very narrow pass band filter, you can shift the band completely off the target wavelength and you will see nothing. You may have heard people talking about what f-ratio a narrowband filter can be used with...this is the problem they are talking about.  Normally f/3 is okay, but f/2 is starting to be too wide a light cone; the angle of the light at the edge of the filter is significantly different than 90 deg so you will see a difference in performance center to edge.  You mentioned that your FOV is about 40degrees.  That means the light is going through the filter at the same angle as if you had an f/1.4 system...way too fast for good narrowband filter performance!  If possible you should mount the filter somewhere between the objective and the field lens.  Maybe try as an experiment comparing what you see when you switch the filter's position from in front of the objective to between the field lens and your eye.

 

Cheers,

 

Jim T.

[gman1971]

PVS-7 lens are rated f/1.2, and the Orion 1.25 seems fine attached on the eyepiece. Maybe the filter is too far away? I don't think I can stick the filter inside the pvs-7.

 

I can try using a 10X magnifier see what I get... stay tuned..

 

An astrocamera requires some exposure to see anything while the NVD does not. 

 

 

G.

[gman1971]

So I ended up attaching the NVD to my ED80 APO triplet, and it is certainly a sad filter, it is.. While it shows the nebulae, and you can certainly see the Horsehead nebula, but is not like the Orion filter that has some serious contrast goodness going on... this thing is dull... which probably means what you stated in your post, the H-a light passing is just not much... and the nebulae look dim, when they should look bright against a dark green background on the NVD, especially with just a meager 20x zoom on the ED80...  Means more exposure to achieve what the Orion H-a can do in probably 1/3rd of the time... oh well... 

 

For what I paid is probably okay, but TBH, I am thinking about selling and getting the Baader, which seems it has a much higher transmission on the H-a line... so things will appear bright and contrasty... perhaps is the cheap glass that is used... don't know...

 

but plainly put: these are not the filters you're looking for if you are using night vision gear for stargazing.

 

G.

[TareqPhoto]

One day i hope i can buy that NVG and try it myself, and i am eligible for that because i have Optolong Ha filter but at 36mm and also Astrodon Ha 5nm, so i can see the difference clearly.

[gman1971]

Yes, and you'll certainly see the difference, again, the Optolong 7nm is indeed an H-alpha, just not as contrasty as the Orion. I would think the Astrodon is going to blow the Optolong out of the water.

 

I think you can do the same thing using fixed exposure time. Set the exposure for 5 seconds on both filters, and the compare which one is brighter.... or contrastier, no post-processing.

 

 

 

G.

[TareqPhoto]

Yes, and you'll certainly see the difference, again, the Optolong 7nm is indeed an H-alpha, just not as contrasty as the Orion. I would think the Astrodon is going to blow the Optolong out of the water.

 

I think you can do the same thing using fixed exposure time. Set the exposure for 5 seconds on both filters, and the compare which one is brighter.... or contrastier, no post-processing.

 

 

 

G.

No need, Astrodon is definitely the winner without a doubt, it is 5nm, while the Optolong is 7nm, so it will definitely show the difference, but i don't have Orion and i don't have Baader to compare it to my Optolong anyway, you had and you said there is a difference, but i saw one photographer using Optolong LRGB and NB filters doing amazing beautiful imaging with them, so is that because of filters or camera or scope.

[gman1971]

Sure, and probably no halos (with nvd halos are kinda irrelevant as the intensifier has halos regardless of how clean the filter is...)

 

And with post processing anything is possible, you can make a long pass look like a narrowband... etc. But the NVDs show real time performance of the filter, so if a filter only lets, say, 50% of the H-a light, it will be dimmer than a 80% filter. With a camera, and enough exposure, post process filtering, etc, any filter can work, but for NVD type of EAA the Orion is the better filter. Shame they don't make it in 2" format to replace my damaged one (the coatings peeled on the side so it has light leakage, why I wanted to try an alternative, but since there is very little information about these things, I had to purchase a few and try them out... and all cheapies are just that, cheapie and they don't show anything on NVD...)

 

I certainly would like to buy the Astrodon at some point, just haven't put my mind (and wallet) to it yet...  

 

G.

[GeezerGazer]

Reading the length of this thread, there is much to consider.  I too use H-a filters with night vision (NV) and have produced images with both my Astronomik 12nm and Optolong 7nm filters.  The visual image at the NV ocular is less impressive than my phone photos (Phonetography) in terms of resolution and visible detail.  The dynamics of NV require a narrower band for visual use, so the Orion Extra Narrow Band filter previously mentioned, may be working at a narrower bandwidth than 5nm.  And, the degree of band shift experienced with only the center 15-20% of FoV revealing the H-a subject, is a strong indicator that the filter is out of phase on the f:1.2 Envis lens.  Although I see band shift on my Envis lens with all of my H-a filters, including an Astrodon 5nm, I do not experience band shift when they are used with a slower prime lens, either in front of or behind the objective.  

 

To keep this post on topic though, I have two 7nm Optolong filters, both purchased during 2017, one 1.25" and one 2", from different retail vendors.  I felt compelled after reading this thread to test each of them along with a 12nm Astronomik filter.  So here (below) are results of my tests, which seem to reveal no color bleed-over.  My Optolong filters do look different from one another though.  The 1.25" has a very distinct gold tone reflective coating on the incoming side and a silver/blue tone reflective coating on the outgoing side.  The 2" Optolong has a bright silver reflective coating on both sides.  I have used them both many times and do not notice any distinguishing characteristics between them in use.  

 

Here is a link to my gallery of images taken with all three filters; most images taken with an iPhone 6+ but a few of the recent ones with a newer XR; these are single images of no more than 1/2s, averaged for 5s-30s in NightCap Camera App on the phone:

 

 https://www.cloudyni...59-geezergazer/

 

The below images were taken with my iPhone using a RGB scale on a MacBook Pro (old 2010 mdl.)

 

Unfiltered:

 

Astronomik 12nm

 

Optolong 1.25" 7nm (gold tone reflective coating)

 

Optolong 2" 7nm (silver tone reflective coating)

 

I cannot address some of the technical issues that have been discussed in this thread, but relating to NV, I can say that I have tested my filters against one another for visual use.  I find that a narrower band filter helps to define the H-a subject with greater contrast between H-a and sky background, but at the cost of attenuating background stars.  And, with a very fast optical system like the f:1.2 Envis prime lens, band shift does interfere with a full FoV transmittance.  At 12nm, there is +/- 5% loss at the perimeter; at 7nm it is +/- 10-15%; and at 5nm, it is 20-30% loss... meaning that the H-a subject only appears in the center 60-80% FoV.  When the optical system is a bit slower as in most telescopes, band shift is not an issue when using NV.  

 

In extensive visual testing using NV between my 7nm Optolong and 5nm Astrodon filters, another CNer on the East Coast and I on the West Coast, using different telescopes, found subtle differences between these two filters, sometimes preferring one over the other for specific targets.  If interested, our test results can be found in this article:

 

 

 https://www.cloudyni...astronomy-r3135

 

NV does change the parameter of this thread, but I use narrow band H-a filters to achieve realtime visual results and the subjective interpretation of those results have some merit, even if from this unique perspective.  I have no personal interest of any kind in ANY company making filters.  Actually I like all of my H-a filters for different reasons. But I will say that I do not use the Astrodon 5nm for images; I use the 12nm most of the time as it permits more light with a wider pass band which does not stress the NV or my phone camera.  For visual use with NV, I use the 7nm Optolong a little more often than the 5nm Astrodon; a personal choice based on the limitations of each filter.  

[GeezerGazer]

Yes, and you'll certainly see the difference, again, the Optolong 7nm is indeed an H-alpha, just not as contrasty as the Orion. I would think the Astrodon is going to blow the Optolong out of the water.

 

I think you can do the same thing using fixed exposure time. Set the exposure for 5 seconds on both filters, and the compare which one is brighter.... or contrastier, no post-processing.

Gman, I've used these filters with NV and found the differences to be surprisingly subtle (see previous post).  There is greater contrast with the 5nm, but it is offset by star attenuation.  There are always tradeoffs.  

 

I did check on the former Orion Extra Narrow Band H-a filter and it was described as 7nm.  Pwang liked its NV performance too, but also had trouble with it delaminating.  Orion no longer sells this particular filter.  

Edited by GeezerGazer, 24 February 2019 - 01:07 AM.

[Rlakjdlsj]

I haven't read  every post in this long thread, but I don't think I saw any mention that Optolong have a reputation that they are perhaps 'lacking in quality' of more expensive filters because there is a long standing claim of patent infringement against them.  

 

When they first came out a few years ago, there were several threads on CNs about a statement on the Astronomik filters website, essentially accusing Optolong of 'stealing' a patented filter holder design from Astronomiks.  As I remember some CNs members were concerned, others didn't care a rats a%% because they were cheaper than most other major brands.  Of course patent infringement, cheap 'knockoffs', and lack of quality control, are not exactly unknown from many Chinese companies for many products.  Their statement is still on the Astronomik site as it has has been for several years:

 

https://www.astronom...nese_copies_en/

 

as always, it is buyer beware.  nice to see someone doing actual tests and discussion.  

Edited by Ron359, 24 February 2019 - 12:13 PM.

[Pantalei]

I haven't read  every post in this long thread, but I don't think I saw any mention that Optolong have a reputation that they are perhaps 'lacking in quality' of more expensive filters because there is a long standing claim of patent infringement against them.  

 

When they first came out a few years ago, there were several threads on CNs about a statement on the Astronomik filters website, essentially accusing Optolong of 'stealing' a patented filter holder design from Astronomiks.  As I remember some CNs members were concerned, others didn't care a rats a%% because they were cheaper than most other major brands.  Of course patent infringement, cheap 'knockoffs', and lack of quality control, are not exactly unknown from many Chinese companies for many products.  Their statement is still on the Astronomik site as it has has been for several years:

 

https://www.astronom...nese_copies_en/

 

as always, it is buyer beware.  nice to see someone doing actual tests and discussion.  

I've heard that Astronomik only patented their clip filters for Germany, (not even Europe) that's why some Optolong dealers state that they can deliver to most countries, but not to Germany. 

[Pantalei]

whilst exploring this topic, which is really interesting, I've found an article on 365telescopes.com that relates to optolong and zwo filters... they took some spectrum images via a bench spectroscope...

http://www.365telesc...mission-report/

[jimthompson]

I haven't read  every post in this long thread, but I don't think I saw any mention that Optolong have a reputation that they are perhaps 'lacking in quality' of more expensive filters because there is a long standing claim of patent infringement against them.  

 

When they first came out a few years ago, there were several threads on CNs about a statement on the Astronomik filters website, essentially accusing Optolong of 'stealing' a patented filter holder design from Astronomiks.  As I remember some CNs members were concerned, others didn't care a rats a%% because they were cheaper than most other major brands.  Of course patent infringement, cheap 'knockoffs', and lack of quality control, are not exactly unknown from many Chinese companies for many products.  Their statement is still on the Astronomik site as it has has been for several years:

 

https://www.astronom...nese_copies_en/

 

as always, it is buyer beware.  nice to see someone doing actual tests and discussion.  

I would not say that Optolong filters are lacking in quality.  If anything they have stood out amongst the many other Chinese manufacturers as a company that provides a consistent quality good value product.  Have they copied ideas from other companies?...Yes, they certainly have.  However if you have any experience with Chinese culture you would understand that is just how things work in that part of the world.

 

Cheers,

 

Jim T.

[Rlakjdlsj]

I would not say that Optolong filters are lacking in quality.  If anything they have stood out amongst the many other Chinese manufacturers as a company that provides a consistent quality good value product.  Have they copied ideas from other companies?...Yes, they certainly have.  However if you have any experience with Chinese culture you would understand that is just how things work in that part of the world.

 

Cheers,

 

Jim T.

The reports in this thread of 'questionable' Optolong quality speak for themselves.  Astronomik speaks for itself and it legal issues.   China is no longer a '3rd world' country.  It entered the hight tech and big business international world a few decades ago. They no longer can rely on the 'excuse' of a 'backward' culture.  Making spectroscopic filters requires high technology and technical standards, not village craftsman each working to his own standard. Clearly Optolong is just another example of the larger trade issues with China and other countries  stealing competitors data and designs for financial advantage, since they are clearly aware of and well educated in 'western culture' of patent law and intellectual property.  That alone is ironic of course since its still a 'communist' economic system but running by the rules of unregulated Darwinian capitalism.  But thats how you 'get rich quick' -at the expense of others.   Independent 'testing' and users who take a chance, will show what their true quality standards are.  It applies to the guys who came up to me in Beijing parks with a coat full of "real Rolex" watches for a hundred US dallar, or the guy with hands full of high powered green lasers for 5 US dallar or spectroscopic filters sold for 1/2 or less the price of filters made in the 'western world'.  

 

Because of the so-called, 'cultural differences,'  aka lack of ethical business standards relative to the 'west', "buyer beware" and "trust but verify" are rules that astro-consumers need to strictly apply unless they just like gambling with their 'disposable' income.  And maybe for many 'amateurs' spectroscopic filters that are not quite up to 'standard' or randomly some are good and some, as we used to say about lemon cars, made on friday afternoon.  But for 1/2 price is going to be 'good enough'.  Then they shouldn't howl or fret when they have more trouble making good or great images after many hours on many dark and cold nights with a mount, camera and scope they just spent $5K or $10K or more on.  Its not like your life or your scientific reputation as a pro-astronomer or other scientist/engineer is at stake.  

Edited by Ron359, 01 April 2019 - 11:09 AM.

[StarMike8SE]

I have the new version of their 7nm Ha filter and no halos.  I was very happy with this. Alnatek was a real issue with the older filter

 

[TareqPhoto]

I have the new version of their 7nm Ha filter and no halos.  I was very happy with this. Alnatek was a real issue with the older filter

 

Because of the camera maybe, there is one member just today minutes ago asked or started a topic asking between ASI1600 and ASI183, another member replied about amp glow and microlensing, so i suppose that ASI183 doesn't have that microlensing issue so it doesn't give that halo?

[james7ca]

Because of the camera maybe, there is one member just today minutes ago asked or started a topic asking between ASI1600 and ASI183, another member replied about amp glow and microlensing, so i suppose that ASI183 doesn't have that microlensing issue so it doesn't give that halo?

Microlensing artifacts should look different than the simple halos produced by the optics or filters. Microlensing almost always shows a crosshatch pattern. That said, the IMX183 doesn't show as much microlensing as does Panasonic's 1600.

 

In any case, below is what I got several years ago using a Baader 7nm Ha filter with an uncooled ASI174MM camera on a Tele Vue NP127is. In this case, I think the halos are from the scope, while the diffraction spikes are from the sensor (but, I actually like both "artifacts").

Attached Thumbnails

• 

Edited by james7ca, 02 April 2019 - 11:25 AM.

[TareqPhoto]

Microlensing artifacts should look different than the simple halos produced by the optics or filters. Microlensing almost always shows a crosshatch pattern. That said, the IMX183 doesn't show as much microlensing as does Panasonic's 1600.

 

In any case, below is what I got several years ago using a Baader 7nm Ha filter with an uncooled ASI174MM camera on a Tele Vue NP127is. In this case, I think the halos are from the scope, while the diffraction spikes are from the sensor (in this case, I actually like both "artifacts").

Ah ok, thank you very much!

[AdamJ]

Because of the camera maybe, there is one member just today minutes ago asked or started a topic asking between ASI1600 and ASI183, another member replied about amp glow and microlensing, so i suppose that ASI183 doesn't have that microlensing issue so it doesn't give that halo?

Everything shows some sort of halo on Alnatek I have even seen 3nm AD Ha images that show a halo on Alnatek. 

[TareqPhoto]

Everything shows some sort of halo on Alnatek I have even seen 3nm AD Ha images that show a halo on Alnatek. 

Ok, then for me i should just forget about this region and Alnitak and use whatever filter even with issues, after all i saw one link only in the past of a test comparison between Optolong LRGB and Baader LRGB, and the conclusion was that Optolong was slightly better than Baader, and that was long time ago, Optolong maybe now has better LRGB, i don't remember if the test included NB filters too, sounds even if it does than Optolong is also that good as Baader or slightly better, but here in this forum it sounds that Optolong is not that good, not as Baader for example, i won't talk about Astrodon or Astronomik [or Chroma], those are in another class.

[Greenflash1]

Guys, using an LED screen is not a substitute for spectrometer. Keep in mind, the emitters are not narrowband. Blue LEDS will have a long tail in emission spectrum that includes green and some red; green includes some blue and red tails, etc. think about this a minute….