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White halo with 127ED

Astrophotography Observing Refractor Visual
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#1 otterspace

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Posted 19 September 2022 - 12:26 PM

Hi All,

 

I recently got a second-hand ES 127ED, the first gen.  The first viewing was testing and looking at Jupiter and Saturn.  I was able to focus to a sharp image.  Both showed a defined white halo around the object, about 5x the diameter of them.  It was almost as light as the planet was, making visual difficult.  I can also see spikes from Jupiter's moons

 

At first I thought it was atmospheric conditions, but here in Salt Lake City it's dry and no clouds.  I pulled out my WO GT71 and didn't get any halos while using the same diagonal and eyepieces.  This eliminated light scattering due to high clouds, and over magnification of the eyepiece.  I used both eyes and I don't have cataracts. (yet)  It was cooled to ambient temps.  It appears to be collimated, as when I defocus it I can see an even pattern in the circle.  I'm sure I could test this more thoroughly but was looking for any possible reasons for the halo.  All optics appear clean.

 

This topic was discussed then archived before but never satisfactorily answered.  A halo with the 127ED but no halo with the GT 71 rules out atmosphere, eyepieces and diagonal, and eye problems.  My wife experienced the same visual halo. When I move the planet to any position in the eyepiece it shows the same halo with no changes.

 

Eyepieces used:

ES 82 degrees Series 18mm

Celestron Lumos 82 degrees 7mm

Meade Super Plossl 26mm LP


Edited by otterspace, 19 September 2022 - 12:37 PM.


#2 truckerfromaustin

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Posted 19 September 2022 - 01:17 PM

Have you tried looking at a bright star to check for a halo? Jupiter and Saturn are very bright right now. I'm thinking that your scope is picking up scattered light as a result. A variable rate polarizing filter might soften the halo, but it's probably just better to live with the glow. An expensive, high quality eyepiece might be a way to test the idea, if you can borrow one.

#3 otterspace

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Posted 19 September 2022 - 02:03 PM

It's a hard pill to swallow that three good eyepieces are all showing the same halo, on a telescope that should be good for planetary viewing. Using the WO GT71 never had these problems using the same eyepieces. Leads me to believe the 127ED is the culprit somehow.  I'll look at a bright star, I'm guessing will show the same diffraction spikes that Jupiter's moons showed.

 

I'll put my ASI294MC on it soon and see if it shows the halo in an image.


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#4 truckerfromaustin

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Posted 19 September 2022 - 04:51 PM

The GT71 has less aperture and much less light gathering capability. I'm pretty sure that you are seeing scattered light to the brightness of the planets. I can't rule out the atmospheric conditions since a clear night can be affected by humidity, dust, smoke, and even wind at higher elevations. The high magnification used for planetary viewing will magnify the problem.

You might have been the victim of smoke from the wildfires in California or Washington.

Is your 127 a doublet or triplet? I think you might have the old f-6.5 achromatic version. You can expect it to have chromatic aberration at higher magnification on bright objects.

Edited by truckerfromaustin, 19 September 2022 - 06:24 PM.


#5 sevenofnine

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Posted 19 September 2022 - 07:15 PM

My Google search says the ES127ED is an air spaced triplet with "virtually" no CA. Your scope should do well for a refractor but there will always be some in that type of scope. If it's great on other objects, I would just accept it...but that's me. Any mirrored scope will show no CA. That's why I added a Mak to my collection waytogo.gif


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#6 Russell Smith

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Posted 21 September 2022 - 12:11 PM

I would try another diagonal and see if thats it. if not do a star test if the rings are not perfectly round its not collimated.


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#7 otterspace

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Posted 21 September 2022 - 12:16 PM

I tried a different diagonal already.  Same result.  I'll do star tests this weekend.


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#8 truckerfromaustin

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Posted 28 September 2022 - 04:27 PM

Have you had a chance to test your scope? Just wondering.

#9 otterspace

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Posted 28 September 2022 - 05:15 PM

Sorta.  I tried visual with bright stars and they have the halo also.  I just got the final ring to mount the camera properly and will test soon to see if images have the halo also, and do a star test to capture the images for you to check out.


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#10 VincenzoZito

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Posted 29 September 2022 - 05:10 AM

Hi,

It could be reflections from the focuser tube.
You could test, with some matte black cardboard to make a quick front lens hood about 15cm long and roll up the matte black cardboard inside the focuser tube.
Test with and without diagonal.



#11 otterspace

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Posted 03 October 2022 - 10:54 PM

I did a few test shots with my 294MC, and they all came out the same.  Notice how the stars and their halo have the star slightly off center, closer to the center of the image. The nebula isn't very clear either. I am using the Hotech FF and there aren't star trails so I doubt that is the issue.  Also I wasn't using the FF when using visual and got the halo too.

 

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#12 PKDfan

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Posted 03 October 2022 - 11:15 PM

Hi otterspace!

Im sorry to read of your troubles.

Its sure looks like a misalignment coma but i don't think the fuzz should be there along with it.

So i am scraping the bottom of reasons why.

Fuzz usually indicates a foreign surface visitor like maybe a barely there oil sheen thats causing the spurious stuff seen so a very close inspection of the objectives surfaces needs to be ascertained.


The misalignment might settle out by a VERY GENTLE vertical shaking of the objective to hear if any moves and rattles and then retighten to just snug up the beauty ring.

BUT i have zero experience with that so MUCH CAUTION please !!!




Clear clean skies

#13 truckerfromaustin

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Posted Yesterday, 08:49 PM

I'm thinking something similar to what PKDfam answered. I'm wondering, if there's just a minuscule amount of oil or water vapor might be trapped in the scope or possibly a small amount tilt in the light path.

CS, Greg


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