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Comparing the Baader 7nm to atila 3.5 nm filter

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#1 Dale Eason

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Posted 23 July 2020 - 02:59 PM

Heart nebula from my LP Bortle 8  drive way.  Well I tried last night.  However my 7nm image on the left is out of focus.  Oh, well better luck next time.

10 inch F3 TV 55 mm afocal.  Camera Samsung note 5.  Baader Ha 7nm on the left.  Atila HA 3.5 on the right.

 

4 second exposure ISO 400.  Temps were a bit cool at 58 deg F at 2am.

 

Visually the 3.5 was very dark and I found the 7nm easier to see with my Mod3C in the scope.  Handheld at 2x I like the contrast of the 3.5 better.

Attached Thumbnails

  • heart7-3p5.jpg

Edited by Dale Eason, 23 July 2020 - 03:00 PM.

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#2 GOLGO13

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Posted 23 July 2020 - 04:12 PM

Always nice to have a mix of HA filters I feel. I have 12, 8, 6 and 3.5 coming soon. There are cases for each type depending on scope and target.
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#3 Jeff Morgan

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Posted 24 July 2020 - 09:42 AM

Heart nebula from my LP Bortle 8  drive way.  Well I tried last night.  However my 7nm image on the left is out of focus.  Oh, well better luck next time.

 

I started using a Bahtinov mask last month. YUGE difference.

 

Now my only issue is remembering to remove the mask before I burn thru 10 or 20 exposures wink.gif 

 

Farpoint Astro sells them, but at that aperture it would probably be a little X-acto blade work at home.



#4 Dale Eason

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Posted 24 July 2020 - 03:39 PM

So far I find that if I remember all I need to do is zoom the phone image and then focus for good star images.  I just forgot to do that after replacing the filter.  Which requires removing the eyepiece with the camera attached and not swirling the camera on the NV causing the diopter setting to move.  I need to remember to pay attention to Focus each time I do that.  

 

However in spite of the number of images I have posted here might imply, I actually don't photograph much.  Until NV I never did.



#5 GeezerGazer

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Posted 25 July 2020 - 03:59 PM

Nice report Dale.  I have found similar results.  The 3.5nm does make a big difference under severe LP, providing increased contrast for a better visual image of H-a.  At dark sites, it helps to provide better definition of fainter H-a.  I do appreciate the value of the narrow band filter... but I'm still using my other H-a filters too.   The 3.5nm does provide better results with faster optical systems... if the optical system being used is slower, the benefits of the 3.5nm also fall off.  As the focal ratio increases, increased noise in the NV image becomes more prominent.  The faster the optics, the better the 3.5nm filter will perform.  Then there is the issue of LP and how it effects filter performance.  Everything seems to work better under darker skies.  

 

An instructive test is to apply the filter to a fast objective lens with an aperture ring, like a camera lens.  While looking at an H-a subject, rotate the aperture ring to a slower speed (higher F-number) and watch for where the increased noise or darkness of the subject becomes an issue.  It's an easy test and may help in understanding under what conditions and with what optical systems you will choose to use the filter.  I repeat this test with different H-a subjects, from faint to very bright.  This type of test has been helpful to me for filter selection... mainly for knowing what filter I should use with specific optical systems from f:1.3 to f:7.  

Ray


Edited by GeezerGazer, 25 July 2020 - 04:05 PM.

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#6 GOLGO13

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Posted 27 July 2020 - 03:21 PM

Got my 3.5nm in the mail today. Looks nice. Unfortunately it was clear last night but not looking clear for a few days.

#7 jay.i

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Posted 27 July 2020 - 06:37 PM

Got my 3.5nm in the mail today. Looks nice. Unfortunately it was clear last night but not looking clear for a few days.

Where did you get yours? The 2" is out of stock everywhere :(



#8 GOLGO13

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Posted 27 July 2020 - 06:47 PM

I'm all 1.25 inch right now. Agena.

#9 jay.i

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Posted 28 July 2020 - 04:25 PM

I'm all 1.25 inch right now. Agena.

Ahhh gotcha. I decided to go with 2" as I'm probably gonna end up going afocal to get the speed needed for such a narrow bandpass. May have to wait months, hopefully not that long!



#10 Gavster

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Posted 28 July 2020 - 04:51 PM

Ahhh gotcha. I decided to go with 2" as I'm probably gonna end up going afocal to get the speed needed for such a narrow bandpass. May have to wait months, hopefully not that long!

Just get the chroma 3nm Jay :)


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#11 jay.i

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Posted 28 July 2020 - 04:58 PM

Just get the chroma 3nm Jay smile.gif

For over triple the price... I don't think I can swing that. If you decide to let one go though let me know! wink.gif


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#12 GOLGO13

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Posted 28 July 2020 - 10:46 PM

The 3.5nm seems quite good so far. Compared to my 6nm Astronomik I think it’s better contrast but somewhat subtle. But I have felt that way with near all my filters. The only one I had an issue with was a 5nm Astrodon which I assume had an issue after testing other filters.

I think the detail increases at a subtle level as I jump from 12 to 8, 8 to 6, and now 6 to 3.5. I’m sure if I went from 12 to 3.5 I would see a larger difference. However, I do think it is worth having a spread.

The new 3.5 appears to be a winner looking at imaging forum discussions.

#13 Jeff Morgan

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Posted 28 July 2020 - 11:35 PM

Just get the chroma 3nm Jay smile.gif

 

Yep.

 

1) Narrower.

2) Impeccable quality in the imaging community.

3) Hate sending any more money to China. Even if it means going without. Or working an extra day to get something better.

 

A very tight filter is percolating up my Buy List. When I go below 7nm - it may not be Chroma. But it will absolutely not be made in China.


Edited by Jeff Morgan, 28 July 2020 - 11:36 PM.

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#14 jay.i

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Posted 29 July 2020 - 09:27 AM

Yep.

 

1) Narrower.

2) Impeccable quality in the imaging community.

3) Hate sending any more money to China. Even if it means going without. Or working an extra day to get something better.

 

A very tight filter is percolating up my Buy List. When I go below 7nm - it may not be Chroma. But it will absolutely not be made in China.

I hate giving money to China too Jeff, I really do. But as someone who just dropped 5 grand on the monocular and has yet to look through it, I can't justify spending $800 on a filter (especially one that requires fast optics that I lack except with afocal use). I can much more easily justify $320 which is still a lot for my aforementioned situation. I'd hate to spend $800 and find that I don't have as much use for a super narrow filter as I thought/hoped I would. But, I'd love to at least give it a shot and it's easier to swallow a $320 pill in that case.



#15 GOLGO13

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Posted 29 July 2020 - 04:06 PM

Quality seemed pretty good. I don't get too worked up about China. Can be hard to avoid sometimes. Chinese quality has improved on many products. 

 

But for this one I have the same opinion as Jay. It's a heck of a lot cheaper.

 

For me, I'll spend a little more for American made. But there comes a point where that only goes so far. And there are not too many American made astro products (I do love my Brandons though).

 

I do have a Chroma 8nm and it's very good. Where are Chroma's made?

 

My only complaint on the Chroma is the size of the filter is too wide. That makes it more difficult to use. I mostly use it for 1x observations.


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#16 GeezerGazer

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Posted 17 August 2020 - 01:35 PM

Where are Chroma's made?

 

My only complaint on the Chroma is the size of the filter is too wide. That makes it more difficult to use. I mostly use it for 1x observations.

Chroma's are made in Vermont; it's an employee owned company.  Agreed, their filter cells are extaordinarily long.  It has been posited by some that Chroma actually makes filters for Astrodon (now owned by Far Point Astro).  I previously sent my Astrodon 5nm filter to Gavster, since he had the 5nm Chroma for a direct comparison of the two filters.  He found little if any discernible difference.  

 

I too have found subtle differences between filters of differing band pass.  Between a 6 Astronomik and a 7 Optolong, I see no useful difference with my optical systems, under my skies.  Between an 8 Chroma and 7 Optolong, likewise almost no distinguishable differences.  Even between a 5 Astrodon and the 7 Optolong, the differences were subtle (see this comparison between a 5 and 7nm in 3 different scopes:)  https://www.cloudyni...astronomy-r3135

 

But between a 6-7nm filter and the 3.5nm Antlia, I do see distinct improvements in nebular contrast.  That contrast improvement comes at the cost of star attenuation and the special type of vignetting from band shift.  Stated many times previously, there is a difference in what filters are most useful for visual use as compared to photography... even with a phone camera.  For visual H-a use, I have settled on 12, 7 and 3.5nm.  Use of these filters depends on which scope I'm using, how much LP is present and how bright the H-a subject is.  

 

For imaging with NV, I now have five H-a filters.  My plan is to sell two... after I have explored what each one does with my imaging optics.  I had the Astrodon 5nm but sold it, actually preferring the Optolong 7nm filter most of the time.  But now I have a Chroma 8 and an Astronomik 6 to compare against the 7.  What I am sure of, is keeping the 3.5 and the 12nm filters.  What I'll decide is which of the 6, 7 or 8nm filters I will keep for imaging.  

 

I don't think it can be overstated how differently these filters react to local sky conditions (degree of LP), optical aperture and focal ratio.  Vignetting from band shift is tolerated differently by observers and personal preference may steer a user to less star attenuation.  There's really no way of knowing which filter you will prefer unless you try them.  But between filters of 1nm difference, the changes are so small that it seems unlikely you will detect them except on very specific H-a subjects.  A larger aperture might make it easier to see differences, but my experience with modest apertures (3" to 8") has shown subtle if any noticeable differences.  

 

I have been asked why I keep a 12nm filter when a 6nm or 3nm show nebulae so much better.  My answer is the 12nm shows much less band shift (vignetting) and more stars... and it makes the nebula appear more as a translucent gas than as a solid mass.  This is a choice based on personal preference. But if I'm tracing faint nebulae, I'm much more likely to use the 3.5nm so I can actually see it.  My experiment on Sh2-27 showed that the 7nm barely revealed this nebula as a non-specific blob, whereas the 3.5nm filter revealed detail, showing the massive face I dubbed as an Ork (currently, the first photo in my gallery).  This was from a blue zone site in CA... from a black site, like I sometimes visit in Nevada, the 7nm or a 6nm filter might have worked fine in revealing detail... because of less light pollution which allows for greater contrast using a wider band pass filter.  From my red zone home, Sh2-27 is basically invisible with any filter.  


Edited by GeezerGazer, 17 August 2020 - 01:58 PM.



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