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685nm Baader IR pass filter

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#1 GOLGO13

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Posted 10 September 2021 - 09:51 PM

The Baader 685nm IR pass filter is killer in light polluted skies. Combined with gain control, you can really get a nice view of the sky. At 1x it makes the Milky Way stand out really well. Way better than non-filtered. 

 

I consider it a must have for NV in light pollution. I'm in Bortle 6 skies and it makes a big difference. I'm not sure how it would work without gain control though. If I turn the gain all the way up it's not as pleasing. But if I dial it back a bit you can find a really nice view. 

 

I like to use this at 1x for seeing satellites and meteors, but also the Milky Way in the summer.

 

It works well in the telescope also for sweeping the Milky Way and other objects like Andromeda etc.

 

 



#2 Mazerski

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Posted 10 September 2021 - 10:10 PM

GO,

 

I agree in LP sky the 685 is a must... for example M22 is in the lower light pollution band and the 685 thru scope shows it well with darker background.

 

Have you compared the 685 vs. 642 for 1x Milky Way and and thru scopes? I go back and forth between 6nm Ha and 642 IR on DSOs such as the Eskimo, NGC40, M42 as the 642 shows nebulosity as well as more stars than Ha. Even M57 looks good with 642 IR. A nice feature in using filter wheel is immediate comparison of filters.



#3 GOLGO13

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Posted 10 September 2021 - 10:21 PM

GO,

 

I agree in LP sky the 685 is a must... for example M22 is in the lower light pollution band and the 685 thru scope shows it well with darker background.

 

Have you compared the 685 vs. 642 for 1x Milky Way and and thru scopes? I go back and forth between 6nm Ha and 642 IR on DSOs such as the Eskimo, NGC40, M42 as the 642 shows nebulosity as well as more stars than Ha. Even M57 looks good with 642 IR. A nice feature in using filter wheel is immediate comparison of filters.

For the 642 do you mean the Astronomik UHC filter? I have tried the two of them before, but I can't remember exactly how they compared. I remember thinking the 685 provided more contrast. The UHC let in some nebulas but not as well as the HA filters do. 

 

I don't use the 610 very often in my skies. But I could see them being useful maybe in a near dark sky maybe.



#4 Dale Eason

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Posted 10 September 2021 - 10:22 PM

Here in Bortle 8 skies it is my go to filter for star stuff.   Galaxies, clusters, Milky way.



#5 ButterFly

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Posted 11 September 2021 - 08:51 PM

The 685 is nice.  A good bit of the Swan survives with the 685, even at 1x.  It darkens nearly all of the dark constellations in the Milky Way compared to the 642, without HII blobs distracting me with their beauty.  The two sets of doubles that seem to be illuminating the Swan's body are easier to see unfiltered in my 15", even though they still survive the 685.  Sliding in h-alpha is just fun at that point.

 

The Eagle next door gets killed by the 685.  Even in my 15" under fairly dark skies, the pillars disappear.  It's really good for separating out the reflection portions, and in the case of the Eagle, leaving only the cluster behind.  A tiny, tiny portion survives the 685 between the top of the pillars and the big dark nebula jutting in perpendicularly.  The Lagoon/Trifid have lots of reflection variations.  I am eagerly awaiting Orion, which I have not yet probed with 685/642/h-alpha.  I'm expecting the Huygens region to survive, with the bat wings getting the brunt of the killing.

 

My Lumicon night sky h-alpha is very similar to the Astronomik 642, and honestly very hard to see differences.  The difference is that the 642 has a cutoff around 850 but not the Lumicon.  It is nearly parfocal with my Baader 685, whereas the 642 is not.  That's a huge plus in the filter wheel next to the 685.  Even at 1x, the focal shift is noticable.

 

I have very dark skies nearby.  I prefer galaxies and clusters unfiltered, but I can get away with it.  H-alpha filters work on the nearby big spirals like M33 and M101, which have big noticable and distinct HII regions, but not M31, which really doesn't.  My 15" isn't really enough for M51's.  Dust lanes can be darkened with IR pass like any other part of blank sky.  The galaxy dims, but there is usually enough contrast left over, especially with the darkened lanes.



#6 Mazerski

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Posted 11 September 2021 - 09:18 PM

GO // Butter,

 

Yes, the Astronomik 642 IR. It depends on the objects... looking tonight at various globulars and using a 685 (Bortle 7). I just looked at NGC40 and its very bright with Ha (12.5" NewMoon) and with 685 a little is still visible but with 642 it looks best as the "halo" and central star are visible. Next time you see M42, try with 642 - I think it looks great. 

 

Some of the Lagoon, Trifed and Omega are visible with 642 and the Eagle is not. However, these 4 nebulas require Ha filter; but with 5x or so hand-held, the 642 shows the MW clouds and you can see stuff for 3 of the nebulas.

 

M51 -- It looks terrible from my location, meaning its not worth looking at... when I met Jeff M in Arizona in May, he set up a 5" refractor and sky was dark... the view of M51 was fantastic, just like photos.



#7 Jethro7

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Posted 12 September 2021 - 05:03 PM

The Baader 685nm IR pass filter is killer in light polluted skies. Combined with gain control, you can really get a nice view of the sky. At 1x it makes the Milky Way stand out really well. Way better than non-filtered. 

 

I consider it a must have for NV in light pollution. I'm in Bortle 6 skies and it makes a big difference. I'm not sure how it would work without gain control though. If I turn the gain all the way up it's not as pleasing. But if I dial it back a bit you can find a really nice view. 

 

I like to use this at 1x for seeing satellites and meteors, but also the Milky Way in the summer.

 

It works well in the telescope also for sweeping the Milky Way and other objects like Andromeda etc.

Hello GOLGO13,

I agree the 585nm IR Longpass filter is best on Globular Clusters and playing in the MilkyWay Star clouds and dust lanes these artifacts just pop. I find that a 642nm IR Longpass filter is decent compromise between a 610nm and 685nm IR Longpass filters that still allows me to  view Nebulae that are lost to the 585nm IR Longpass filter.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro



#8 bobo99

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Posted 14 September 2021 - 01:45 PM

Hello GOLGO13,

I agree the 585nm IR Longpass filter is best on Globular Clusters and playing in the MilkyWay Star clouds and dust lanes these artifacts just pop. I find that a 642nm IR Longpass filter is decent compromise between a 610nm and 685nm IR Longpass filters that still allows me to  view Nebulae that are lost to the 585nm IR Longpass filter.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

Just to clarify, you get a a contrast increase in the milkyway using the 585 longpass?



#9 Jethro7

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Posted 14 September 2021 - 02:11 PM

Just to clarify, you get a a contrast increase in the milkyway using the 585 longpass?

Hello bobo99,

Using the 585nm IR Longpass filter, the Stars and Dust Lanes as well as Star Clusters stand out in the Milkyway. I am not sure if it is just contrast. The 585 Longpass filters out  most all nebulosity. 

 

HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro


Edited by Jethro7, 14 September 2021 - 07:56 PM.


#10 ButterFly

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Posted 14 September 2021 - 07:52 PM

Hello bobo99,

Using the 585nm IR Longpass filter, the Stars and Dust Lanes as well as Star Clusters stand out in the Milkyway. I am not sure if it is just contrast. The 585 Longpass filters out all most all nebulosity. 

 

HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro

Just to further clarify, the 3->2 transition of Hydrogen is around 656nm, and is referred to as h-alpha.  See Balmer series.  You do mean 685nm IR Longpass that filters out "most all nebulosity," right?



#11 Jethro7

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Posted 14 September 2021 - 07:55 PM

Just to further clarify, the 3->2 transition of Hydrogen is around 656nm, and is referred to as h-alpha.  See Balmer series.  You do mean 685nm IR Longpass that filters out "most all nebulosity," right?

Yes


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#12 a__l

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Posted 16 September 2021 - 08:08 AM

This topic probably makes sense if the user of the filters is specifying what kind of lens they are using. Different lenses are used for NVs, some of them already use filtering and using additional filters will probably be less effective.



#13 Gustoresto

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Posted 17 September 2021 - 01:57 PM

Can it be simply stated whether a 6-7nm Ha filter is better or a 685 longpass [optalong]   for specific faint emission nebulae like the veil rosette, california, etc in Bortle 6 skies?     There seems to b some ambiguous reports on this or maybe I'm getting fuzz brained from too many CN posts on NV.  I ordered the 2" 685  Laida from ali express. Will that pass these faint DSOs?      I'm wondering if I can just use this one filter 2 start w my pvs14 handheld w a 3X afocal front lens added.   Thx Gus


Edited by Gustoresto, 17 September 2021 - 01:57 PM.


#14 GOLGO13

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Posted 17 September 2021 - 02:07 PM

6-7nm HA is what you use for nebulas (actually any HA from 12nm to 3nm will work, but 6-7 is a good one). 

 

685 long pass is meant for everything but nebulas in fairly strong light pollution. Things like the Milky Way, star clusters, etc. They won't show nebulas, but they are a good thing to have.

 

If you live in dark skies, you maybe able to skip getting the long pass filters. But they are quite helpful in my Bortle 6 skies.


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#15 Jethro7

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Posted 17 September 2021 - 06:35 PM

findIPAddresses

 

Can it be simply stated whether a 6-7nm Ha filter is better or a 685 longpass [optalong]   for specific faint emission nebulae like the veil rosette, california, etc in Bortle 6 skies?     There seems to b some ambiguous reports on this or maybe I'm getting fuzz brained from too many CN posts on NV.  I ordered the 2" 685  Laida from ali express. Will that pass these faint DSOs?      I'm wondering if I can just use this one filter 2 start w my pvs14 handheld w a 3X afocal front lens added.   Thx Gus

Hello Gustoresto,

GOLGO13, Is correct. With a 585nm IR Longpass filter you will see very little nebulosity. Star Clusters and the Milkyway dust lanes will stand out. Out of my filter set my go to's are the 7nm Ha Narrowband filter ( for Nebulae ) 642nm IR Longpass filter ( For a compromise, to view both Stars and Nebulae) 685nm IR Longpass filter ( For Stars ) Your choices for how aggressive the filtering you need depends on your Bortle rating ( I live in a Bortle 8 sky) the scope you are using and the quality of the Night Vision Device.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro


Edited by Jethro7, 17 September 2021 - 06:40 PM.



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