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Orion and Atila 3.5

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21 replies to this topic

#1 Dale Eason

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Posted 21 November 2020 - 03:47 AM

First clear night in a month.  Last summer I got the 2inch Atila 3.5 HA filter.  It helped a lot on the Deneb area bringing out more contrast but darken more stars in the process. 

 

 Tonight was my first chance to use it on Orion.  For the first time in my nearly Urban skies I saw Banard's loop easily.  Last year using the 7nm Baader I thought I saw it one time.  No question about it tonight with the 3.5.  I used my Mod3C with Nikon 50 mm 1.8 lens hand held.  Very enjoyable at 26 deg F with no wind.  I only stayed out about 4 minutes.  Grab an go to the rescue.


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#2 bobhen

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Posted 21 November 2020 - 07:32 AM

Just outside of Philadelphia in extreme light pollution and with a 6nm Ha filter and my 50mm repurposed guide scope handheld, I can also see the brighter sections of Barnard's Loop. 

 

Yes to NV, handheld grab-and-go! I had a short less than 20-minute session the other night and observed 15 objects with the 50mm, ranging from the California Nebula to the North American Nebula.

 

Bob



#3 Joko

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Posted 21 November 2020 - 09:54 AM

Like you i have the Antlia 3.5nm. I consider it as a perfect complement to my H-alpha 7nm. Few nights ago i was able to see the Veil Nebula at 1x using the 7nm, should try with the 3.5nm when i remove it from my filter wheel.



#4 a__l

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Posted 21 November 2020 - 05:36 PM

The veil is very clearly visible at the zenith of 7 nm with numerous lights around (3x). I don't think 3.5 nm will add anything new at 1x.


Edited by a__l, 21 November 2020 - 05:37 PM.


#5 Dale Eason

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Posted 21 November 2020 - 10:15 PM

Like you i have the Antlia 3.5nm. I consider it as a perfect complement to my H-alpha 7nm. Few nights ago i was able to see the Veil Nebula at 1x using the 7nm, should try with the 3.5nm when i remove it from my filter wheel.

If you already have one then of course try it.  It will either increase the contrast a bit or dim the view more than you like just depends on the light pollution you have.  


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#6 Joko

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Posted 22 November 2020 - 02:20 AM

The veil is very clearly visible at the zenith of 7 nm with numerous lights around (3x). I don't think 3.5 nm will add anything new at 1x.

FYI 3.5nm always add more details than 7nm if your tube specs are good enough to accept it without too much scintillation. And it is more difficult to see the veil at 1x than 3x. So it might not bring more details with your NVD, I remember you told me you have no spec sheets with your tube. 


Edited by Joko, 22 November 2020 - 03:10 AM.


#7 a__l

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Posted 22 November 2020 - 04:48 AM

Hmm ... what do I need a spec for? I can compare numerous photographs in this section and what I see with my eyes. I don't see much difference for the best photos posted here. Even if there were some problems, I have a fairly large and fast aperture smile.gif
I don’t remember the Veil in 1x. I like the 3x picture better (CF75 lens).  Any objects. The Veil fits completely into the 3x field of view with plenty of room to spare. Why watch what is more difficult to see (1x)? (Although I'm not sure about this, the transparency of the sky has a big influence here, and I looked in very transparent sky, although with lanterns around. ) It's like deliberately making your life difficult. My opinion has not changed.


Edited by a__l, 22 November 2020 - 05:32 AM.


#8 Joko

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Posted 22 November 2020 - 05:59 AM

My opinion has not changed.

It's not about opinion but about facts, you will see more details with a 3.5nm than a 7nm at 1x and 3x. Sorry if you can't compare as you don't have both filters. I'll be pleased to show you the difference if we can meet one day. smile.gif


Edited by Joko, 22 November 2020 - 05:59 AM.


#9 a__l

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Posted 22 November 2020 - 07:07 AM

It's not about opinion but about facts, you will see more details with a 3.5nm than a 7nm at 1x and 3x. Sorry if you can't compare as you don't have both filters. I'll be pleased to show you the difference if we can meet one day. smile.gif

Everything is simple here. Veil in 1x small size. I doubt you will see more details in 3.5 nm. Than I saw at 7nm at 3x. Actually, that's what I meant.


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#10 a__l

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Posted 22 November 2020 - 07:20 AM

I'll add more. When I buy something for a big price (and a 3.5 nm filter is not cheap), I try to figure out what I will get from it.
http://www.loptics.c...ightvision.html
Photo under the caption "M8 through an Antlia 3.5nm H-alpha filter, a Baader 7nm H-alpha filter, a Celestron UHC / LPR filter"
I like 7 nm much more than 3.5 nm.



#11 Joko

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Posted 22 November 2020 - 07:42 AM

I'll add more. When I buy something for a big price (and a 3.5 nm filter is not cheap), I try to figure out what I will get from it.
http://www.loptics.c...ightvision.html
Photo under the caption "M8 through an Antlia 3.5nm H-alpha filter, a Baader 7nm H-alpha filter, a Celestron UHC / LPR filter"
I like 7 nm much more than 3.5 nm.Ver

Thanks for confirming you have never been able to compare by using them but only by looking at pics. And you can read many reviews on Cloudynights comparing the 3.5nm and 6nm/7nm. All tend to explain the 3.5nm brings more details.


Edited by Joko, 22 November 2020 - 07:43 AM.


#12 Mike Lockwood

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Posted 22 November 2020 - 01:14 PM

As usual, photos don't show the same thing as you see visually, especially on one of the brightest nebulae in the sky, the Lagoon (M8).  One person here has drawn the wrong conclusion based on this.

 

The 3.5nm is noticeably higher contrast visually, particularly for low and medium brightness objects.  For observing sites with light pollution, the improved contrast is noticeable.

 

I mentioned this specifically in one post from my thread:

  https://www.cloudyni...f30/?p=10257170

 

I posted comparison images of Sh2-27 in another thread, which CLEARLY show the difference between the 3.5nm and 7nm filters:

  https://www.cloudyni...pha/?p=10261873

 

So there you go.


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#13 Dale Eason

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Posted 22 November 2020 - 01:33 PM

Usually camera images do not do a good job of showing that difference.  However Mike's link to his sh2-27 image is a good example of the improved view that I get of the emission nebulae it my site.

 

Visually the difference I see is better with the 3.5 than the 7nm.  However it can be too dim.  At that point I switch back to the 7.  But I now chose the 3.5 first  then try the 7nm.  Usually going back to the 3.5.  



#14 RedzoneMN

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Posted 23 November 2020 - 09:08 PM

These Antlia filters are hard to come by. 

 

Any reason why these are "better" than Baader 3.5 nm filters?



#15 gatorengineer

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Posted 23 November 2020 - 09:48 PM

I have both a baader fast 3.5 and the Antilia.  They are different.  

 

Baader lets more stars through, and the Antilia gives you better absolute contrast.  Antilia is a relatively new name and  they dont have a well established dealer network yet.  Antilia is NOT front threaded.  

 

I thought I would buy em and try em and keep one, but they are different enough to both be staying,  


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#16 Mike Lockwood

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Posted 24 November 2020 - 12:37 PM

I'm going to point this out again....

 

I have a spectrometer that covers the visual range.  I have offered to measure filters for free if the owner pays for return shipping.

 

I have filter measurements here, and will add new measurements:

  http://www.loptics.c...ra/spectra.html

 

I plan to measure gatorengineer's filter in the future.


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#17 RedzoneMN

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Posted 24 November 2020 - 02:35 PM

I have both a baader fast 3.5 and the Antilia.  They are different.  

 

Baader lets more stars through, and the Antilia gives you better absolute contrast.  Antilia is a relatively new name and  they dont have a well established dealer network yet.  Antilia is NOT front threaded.  

 

I thought I would buy em and try em and keep one, but they are different enough to both be staying,  

Meaning the Baader 3.5 has some broadband leakage?  
 

it’s interesting that per Mike Lockwood the Anglian 3.5 has some leakage too. 


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#18 Mike Lockwood

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Posted 24 November 2020 - 04:56 PM

Meaning the Baader 3.5 has some broadband leakage?  
 

it’s interesting that per Mike Lockwood the Anglian 3.5 has some leakage too. 

Where did I say that?  Why do people keep assuming this?  This is wrong.

 

There is measurement noise in the shorter wavelength portion of the spectra.  This is not leakage, it is simply noise/uncertainty in the measurement, and shows up to ~400nm.  The noise is because the light source is weak at those wavelengths, so the signal/noise is lower.

 

I saw obvious leakage in my friend's Optolong filters (last two plots on my page), you could see other colors through them.  You can see the small bumps in the spectra above 400nm.  It is ANTLIA (like the constellation, everyone is misspelling it) and other filters that I have measured, including this 3.5nm, did not show this.

 

When I have some time, I also intend to measure response as a function of filter angle for the narrowbands that I have, if I can figure out a way to accurately and consistently tilt the filter.


Edited by Mike Lockwood, 25 November 2020 - 12:53 PM.

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#19 gatorengineer

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Posted 24 November 2020 - 06:30 PM

Well when I send the filter to Mike for Testing we will get the results, and see what it does I think the Antilia has some spectra bandshift out......  but that is Purely speculation, the testing will tell.  I am using the  Baader HS to set up the ASA reducer as its front threaded, which I need right now the Antilia isnt.



#20 GeezerGazer

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Posted 29 November 2020 - 03:01 AM

Gator, I put my 3.5nm Antlia in a Blue Fireball filter cell (perfect fit) and used the retaining ring from a Neewer 2" filter cell.  That works perfectly and leaves ~2.4mm of front, female threads.  The Blue Fireball retaining ring can't be used... it's 3mm long, using too much of the front threads.  

 

Mike, when I originally looked at the Antlia testing graph, I interpreted the "bumps" as leakage rather than noise.  You corrected my interpretation in another thread, but I suspect others have interpreted the graphs similarly.  You might make a note in the graph about the distinction.  



#21 Mike Lockwood

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Posted 29 November 2020 - 12:42 PM

Agreed, I have thought about doing it, just have to find some time!

 

Edit:  Done - I annotated the Antlia and an Optolong spectra.  Graphs without annotation should be interpreted similarly. 

 

There might be a small amount of leakage at very short wavelengths, but the measurement is too noisy to confirm this so I won't claim that.


Edited by Mike Lockwood, 29 November 2020 - 06:54 PM.

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#22 gatorengineer

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Posted 29 November 2020 - 07:00 PM

Geezer,

 

You have provided me alot of great tips, and this is likely another one, but I am not understanding.  I think you are saying demount and remount the antilia?  or is there a blue fireball filter drawer I am not seeing in my googling...

 

Mark




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