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Need help with light scatter in eyepieces

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#1 Dan84

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Posted 04 August 2021 - 05:50 AM

EDIT:   Before going any further, please note that I have checked maps for smoke filled skys and that is, by far, the most likely culprit.  The thought of smoke from wild fires entered my mind, however I pushed that idea out of my head and blindly pushed forward.  The result was poor seeing without much of an answer to why, given my equipment and the good state that it is in.  If anything, hopefully this post will help the next person with poor views of the heavens, at least until the smoke clears.

 

Here is one map source, note that it changes, sometimes relatively fast:  https://fire.airnow.gov/

 

I took my telescopes out a few times last year however for the most part I recently got back into astronomy after decades of absence.  I live in town and visibility is usually poor to very poor.  Telescopes: a Sky-Watcher f/9 100mm ED refractor with perfect collimation and a Meade LX65 8" f/10 ACF Catadioptric with GoTo mount, I can put both scopes on the same mount/head.  This evening I mounted both telescopes & rechecked the collimation on the 8".  Primarily I wanted to view Saturn.  It came out from behind some trees at about 10:00p.m. EDT.  By about 12:30a.m. this morning views of Saturn was about as good as it was going to get.  I could see the Cassini Division but barely and I could see Titan, Rhea, Dione and Tethys.  Enceladus was too close to Saturn and I couldn't see it for the glare/light scatter.  I could make out a little color in the clouds on Saturn and for some reason at 300x [6mm UO Ortho & 2x barlow] the Sky-Watcher did the best on detail and the refractor outperformed the 8" no matter the power used, of course the 8" was brighter, in fact Jupiter was too bright.  And, I checked the collimation of the 8".

 

Unfortunately the light scatter in the eyepieces in both telescopes was so bad that it nearly ruined the view of Saturn and did ruin the view of Jupiter.  If it were not for the light scatter everything I saw would have been much better, crisper and more detailed.  I have a variety of eyepieces that I have picked up over the years, none top end but should get the job done, and every one of them had a great deal of light scatter with the somewhat better view University Optics 12.5mm Ortho giving the least amount of light scatter although, as mentioned the 6mm + barlow in the refractor gave the best view.

 

Eyepieces are:  5.5mm 62 degree & 14mm 82 degree Explore Scientific, 6mm & 12.5mm UO Orthos, 7.5mm Orion Epic ED-2, 9mm Fujiyama Ortho, 32mm Meade Plossl, & a very old Celestron Ultima SV series 2x Barlow [the good one, model 93506].  All are 1 1/4" [don't have the money for good 2" eyepieces].  I have a series 4000 f/6.3 field flattener for the Meade telescope but I didn't use it last night on planets.

 

Does looking at a light filled sky in town have an impact?  Should I try to paint the interior of the eyepieces?


Edited by Dan84, 04 August 2021 - 11:10 AM.


#2 luxo II

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Posted 04 August 2021 - 06:09 AM

Ok… since (a) there’s nothing wrong with the ES, Fujiyama, Meade or UO eyepieces (orthos should be fine) and (b) you’re seeing scatter with all eyepieces and both scopes I’m wondering - are you sure the scatter is in the eyepieces and not in your eye ?

 

Naked eye, how do distant street lights appear ? Crystal clear, or the same scattered light ?

 

When did you last visit an optometrist ?


Edited by luxo II, 04 August 2021 - 06:16 AM.


#3 Tangerman

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Posted 04 August 2021 - 06:20 AM

You should also keep in mind that bright targets, such as Saturn, can have their light scattered in the atmosphere and still reach you. This is especially the case when low on the horizon, in high humidity, or with smoke or dust in the air. 


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#4 george tatsis

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Posted 04 August 2021 - 06:46 AM

You should also keep in mind that bright targets, such as Saturn, can have their light scattered in the atmosphere and still reach you. This is especially the case when low on the horizon, in high humidity, or with smoke or dust in the air. 

+1 waytogo.gif, plus too much mag for a planet that is not favorably positioned this year.

 

George


Edited by george tatsis, 04 August 2021 - 06:49 AM.

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#5 Voyager 3

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Posted 04 August 2021 - 06:53 AM

To add to what Tangerman said , thin high clouds too can scatter the light .
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#6 Dobs O Fun

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Posted 04 August 2021 - 06:58 AM

Does looking at a light filled sky in town have an impact? Should I try to paint the interior of the eyepieces?


I have 8" newt/ dob and use in light polluted skies. I have 25mm, 10mm, 6mm plus barlow. I can say I can see pretty good given my optics are not top shelf. I have contact lenses on correctable to 20/30 at least. I also see floaters. My observations of Jupiter and Saturn are below 30° as well. Collimation is good.

I push my scope as much as I can but never yet seen the Cassini. Still working on it. My mind set was let's get higher magnification but the planets seem to dance. I figure elevation, atmosphere and light pollution plus my vision are working against me. Light pollution does not help at least in my case.

#7 MartinPond

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Posted 04 August 2021 - 09:34 AM

All bets are off right now, at least

  while the East US is under a film of smoke

    from the Western  fires.   Night and even daytime long views.

    Jupiter, or a raptor at 10miles,  is a filmy mess. 


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#8 Dan84

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Posted 04 August 2021 - 10:54 AM

All bets are off right now, at least

  while the East US is under a film of smoke

    from the Western  fires.   Night and even daytime long views.

    Jupiter, or a raptor at 10miles,  is a filmy mess. 

I think you have hit the nail on the head.  Wild fires entered my mind, however I pushed that thought away, ignoring it.  Alas, there is a lot of smoke polluting the air and that is the most likely candidate by far.



#9 Dan84

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Posted 04 August 2021 - 11:17 AM

Ok… since (a) there’s nothing wrong with the ES, Fujiyama, Meade or UO eyepieces (orthos should be fine) and (b) you’re seeing scatter with all eyepieces and both scopes I’m wondering - are you sure the scatter is in the eyepieces and not in your eye ?

 

Naked eye, how do distant street lights appear ? Crystal clear, or the same scattered light ?

 

When did you last visit an optometrist ?

At least for the moment the problem seems to be smoke filled skies from wild fires.



#10 Dan84

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Posted 04 August 2021 - 11:17 AM

You should also keep in mind that bright targets, such as Saturn, can have their light scattered in the atmosphere and still reach you. This is especially the case when low on the horizon, in high humidity, or with smoke or dust in the air. 

At least for the moment the problem seems to be smoke filled skies from wild fires.



#11 Dan84

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Posted 04 August 2021 - 11:18 AM

I have 8" newt/ dob and use in light polluted skies. I have 25mm, 10mm, 6mm plus barlow. I can say I can see pretty good given my optics are not top shelf. I have contact lenses on correctable to 20/30 at least. I also see floaters. My observations of Jupiter and Saturn are below 30° as well. Collimation is good.

I push my scope as much as I can but never yet seen the Cassini. Still working on it. My mind set was let's get higher magnification but the planets seem to dance. I figure elevation, atmosphere and light pollution plus my vision are working against me. Light pollution does not help at least in my case.

At least for the moment the problem seems to be smoke filled skies from wild fires.



#12 Thomas_M44

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Posted 04 August 2021 - 12:28 PM

I’d think it most likely your issues are because ofatmospheric conditions and also *perhaps* some of your eyepieces need a bit of cleaning.

 

Eyepiece scatter issues seem unlikely with most of the eyepieces you mention.




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