Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Jupiter - Great at medium mag, ghosting at higher mag

  • Please log in to reply
14 replies to this topic

#1 rkelley8493

rkelley8493

    Viking 1

  • *****
  • topic starter
  • Posts: 553
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 27 May 2019 - 01:44 AM

I used my LX90 for the first time on Jupiter tonight. Started out with the 22mm Nagler which I was using for the initial alignment [113x]. When I slewed over to Jupiter, I was amazed at the finer details compared to my apo. I could see Io's shadow on the planet, and the Great Red Spot had a tail from where it's unraveling. The cloud belts were very well defined with knots from swirling clouds. The moons were also much more defined. Different sizes and colors. Beautiful. 

Next eyepiece I decided to use was 12mm. It seems to be the sweet spot for high mag [208x] on most targets. Not so much this time... Jupiter was cloaked in a bright halo ghost image. My first thought was the eyepiece may have been fogging from coming out of the cool house to the 85º heat & 90% humidity. Tried another eyepiece, 10mm = f/ratio. Same problem. I ruled out the eyepiece being the problem after using several different models & focal lengths. I then remembered having a similar issue in the past with Sirius, though not nearly as bad. 

How would you combat this problem? Is this a common issue with SCT's, or is it an issue with my LX90? I was using a dew shield with a flocked interior. Should I try flocking the inside of the optical tube? Is there an easier fix that wouldn't require taking the scope apart? Any feedback is appreciated! 



#2 T1R2

T1R2

    Mercury-Atlas

  • -----
  • Posts: 2892
  • Joined: 11 Jun 2013
  • Loc: NeverWhere, 35*N

Posted 27 May 2019 - 04:03 AM

Any time I see a bright halo, its usually foggy ep or corrector. A ghost image usually is a larger exact reflected translucent image super imposed over the bright target but it will move when the scope is panned back and forth. Foggy ep's and corrector's on the other hand will produce nothing but a intrusive halo.

 

use dew straps on the eps and corrector.


  • Procyon and rkelley8493 like this

#3 Astrojedi

Astrojedi

    Soyuz

  • *****
  • Posts: 3594
  • Joined: 27 May 2015
  • Loc: SoCal

Posted 27 May 2019 - 10:19 AM

Could also be poor seeing combined with moisture in the air. I get that a lot here close to the coast on days with poor seeing.
  • Procyon, T1R2, Tyson M and 2 others like this

#4 Cpk133

Cpk133

    Apollo

  • -----
  • Posts: 1230
  • Joined: 14 Mar 2015
  • Loc: SE Michigan

Posted 27 May 2019 - 11:27 AM

As the keeper of the swamp gas obsy stated, ghost will move in opposite direction of the target as the is moved in the eyepiece.  I'm guessing halo is what you're seeing, a generalized light haze around Jupiter.  Perhaps you could describe a little more or see if you can find a pic that represents what you were seeing.  When bright objects are low, and you're looking through humid particulate filled atmosphere, you can expect to see bright haze.


  • rkelley8493 likes this

#5 rkelley8493

rkelley8493

    Viking 1

  • *****
  • topic starter
  • Posts: 553
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 27 May 2019 - 11:40 AM

Could also be poor seeing combined with moisture in the air. I get that a lot here close to the coast on days with poor seeing.

That makes sense. Seeing conditions weren't the best.

 

As the keeper of the swamp gas obsy stated, ghost will move in opposite direction of the target as the is moved in the eyepiece.  I'm guessing halo is what you're seeing, a generalized light haze around Jupiter.  Perhaps you could describe a little more or see if you can find a pic that represents what you were seeing.  When bright objects are low, and you're looking through humid particulate filled atmosphere, you can expect to see bright haze.

Haha lol.gif  It was pretty swampy. It looked like there was a spot light on Jupiter that was 2.5 to 3 times its diameter. It almost looked like it was getting reflected twice with one being a larger blurry reflection. But like I said earlier, this was the first time I used this scope on Jupiter, and seeing conditions weren't the best. It's been my experience that you can't judge equipment based on one night of observing. Hopefully conditions will be better next time around.


Edited by rkelley8493, 27 May 2019 - 11:41 AM.

  • Procyon likes this

#6 rkelley8493

rkelley8493

    Viking 1

  • *****
  • topic starter
  • Posts: 553
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 27 May 2019 - 11:42 AM

...  A ghost image usually is a larger exact reflected translucent image super imposed over the bright target but it will move when the scope is panned back and forth...

That's exactly what it was!


  • T1R2 likes this

#7 Procyon

Procyon

    Fly Me to the Moon

  • *****
  • Posts: 6332
  • Joined: 23 Feb 2009
  • Loc: Eastern Canada

Posted 27 May 2019 - 12:27 PM

Saw that ugly halo on some stars last night..........got swamped here. Forecasts shnorcasts....Said humidity was 45, but was 100 outside. Besides the view of the Whirlpool and a carbon star, didn't enjoy much else, packed it all up after 2 hrs at 1am.

 

Defnitely use a dew strap heater and dew shield. Maybe it's all this rain we've been having that produced so much evaporation. 


  • rkelley8493 likes this

#8 Tyson M

Tyson M

    Gemini

  • *****
  • Posts: 3208
  • Joined: 22 Jan 2015
  • Loc: 53 degrees North

Posted 27 May 2019 - 02:57 PM

Could also be poor seeing combined with moisture in the air. I get that a lot here close to the coast on days with poor seeing.

+1

 

I have seen this too, but with low elevation thrown in the mix.


  • rkelley8493 likes this

#9 rkelley8493

rkelley8493

    Viking 1

  • *****
  • topic starter
  • Posts: 553
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 27 May 2019 - 03:15 PM

+1

 

I have seen this too, but with low elevation thrown in the mix.

Yea.. I guess it was just a perfect storm of bad seeing conditions. Very hot, very humid, clouds starting to form, and Jupiter low in the sky. That's a little comforting to know and reassuring. I'd hate to have to make modifications like flocking the interior on a scope that is already very good on its own. 


  • Procyon likes this

#10 luxo II

luxo II

    Viking 1

  • -----
  • Posts: 826
  • Joined: 13 Jan 2017
  • Loc: Sydney, Australia

Posted 27 May 2019 - 05:05 PM

As above it may be down to atmospheric conditions being on the brink of condensing into cloud.

Even if you did conclude the issue is within the OTA flocking is unlikely to make much difference.

Point the scope at the moon one night then walk round the front and have a good into the corrector look to see where the stray light is going and you will find a few interesting clues by what is brightly lit inside. From personal experience doing this with many scopes:

- the inside surface of the tube will be dark because the ring supporting the corrector is doing its job as the aperture stop. Not much point in flocking that.

- the central baffle will be brightly lit particularly nearest the secondary mirror, and quite possibly the inside surface.

- the secondary mirror baffle likewise will be brightly lit inside and out.

Some of this light scattered off the baffles will reach the focal plane causing a “fog” around bright objects. It is particularly bad from machined aluminium surfaces even when anodised black.

A coat of Black 3.0 or similar will help.

Edited by luxo II, 27 May 2019 - 05:06 PM.

  • Procyon and rkelley8493 like this

#11 Procyon

Procyon

    Fly Me to the Moon

  • *****
  • Posts: 6332
  • Joined: 23 Feb 2009
  • Loc: Eastern Canada

Posted 27 May 2019 - 07:45 PM

I'm thinking all that rain that fell followed by the hottest day/night of the year caused massive evaporation. So much evaporation it turned into light but very long lasting fog. Looked like a steam room around here. Temp dropped from 73 to 53F in 3 hours, so that's also playing a huge role on the optics. Jet stream, dust particles, seeing, transparency, all seemed nice & stable.

Pretty much a typical summer night in the Everglades lol.

M94 and the Whirlpool Galaxy looked great though. M94 looks like a giant white ball, that is one bright Galaxy. Easily one of my favorites, with M105 & NGC 3384.

Edited by Procyon, 27 May 2019 - 07:46 PM.

  • rkelley8493 likes this

#12 rkelley8493

rkelley8493

    Viking 1

  • *****
  • topic starter
  • Posts: 553
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 27 May 2019 - 08:22 PM

.... Pretty much a typical summer night in the Everglades lol.

M94 and the Whirlpool Galaxy looked great though. M94 looks like a giant white ball, that is one bright Galaxy. Easily one of my favorites, with M105 & NGC 3384.

Haha, yea I'm right up the street from the Gulf Coast. Far enough away not to get the Gulf Breeze but close enough for all the heat & humidity. Summers are always long & harsh..

M94 is pretty bright! Almost looks like a fat, swollen, foggy star. It's one of the DSO's that isn't picky about telescope apertures. 


  • Procyon likes this

#13 rkelley8493

rkelley8493

    Viking 1

  • *****
  • topic starter
  • Posts: 553
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 29 May 2019 - 02:13 PM

Ok, I have an update on the ghosting issue with Jupiter. Apparently it was just the weather and seeing conditions that night. I didn't have any ghosting issues last night, but Jupiter is still too low in the sky for high magnification. I've noticed this in the Apo too.. anything above 130x and you can see the atmospheric shimmer going on, so it's not scope specific. Just too much atmosphere in the way.


Edited by rkelley8493, 29 May 2019 - 06:05 PM.

  • Procyon and BFaucett like this

#14 Procyon

Procyon

    Fly Me to the Moon

  • *****
  • Posts: 6332
  • Joined: 23 Feb 2009
  • Loc: Eastern Canada

Posted 29 May 2019 - 03:38 PM

- the central baffle will be brightly lit particularly nearest the secondary mirror, and quite possibly the inside surface.

- the secondary mirror baffle likewise will be brightly lit inside and out.

Some of this light scattered off the baffles will reach the focal plane causing a “fog” around bright objects. It is particularly bad from machined aluminium surfaces even when anodised black.

A coat of Black 3.0 or similar will help.

Great stuff. Definitely worth doing, especially if ever needing to remove the corrector. Much better than flocking the inside tube or even putting anything on the inside tube since it's already black.

 

 

Haha, yea I'm right up the street from the Gulf Coast. Far enough away not to get the Gulf Breeze but close enough for all the heat & humidity. Summers are always long & harsh..

M94 is pretty bright! Almost looks like a fat, swollen, foggy star. It's one of the DSO's that isn't picky about telescope apertures. 

Ever get nights with 0/mph stagnant air? I was thinking it may have been the wind but it was blowing at 14km/s. May is usually a 20 C/70F +-5c type of month here. Usually dry but with increased thunderstorms towards the end of the month. This year we've had 4 days of total dryness this month. The average is like 15 days. But like you said, it was a perfect storm.


Edited by Procyon, 29 May 2019 - 03:59 PM.


#15 Procyon

Procyon

    Fly Me to the Moon

  • *****
  • Posts: 6332
  • Joined: 23 Feb 2009
  • Loc: Eastern Canada

Posted 29 May 2019 - 04:02 PM

Ok, I have an update on the ghosting issue with Jupiter. Apparently it was just the weather and seeing conditions that night. I didn't have any ghosting issues last night, but Jupiter is still low in the sky for high magnification. I've noticed this in the Apo too.. anything above 130x and you can see the atmospheric shimmer going on, so it's not scope specific. Just too much atmosphere in the way.

Jupiter, with these conditions? You can count me out, lol. No that's not true, I think it's best to look at it after it's done climbing upwards for at least a couple of hours. Otherwise you'll see a nice handful of thick atmosphere, (thick wavy atmo if there's major turbulance), as it's behind more of Earth's atmosphere at that point.

Definitely need to catch it at it's highest altitude or around that period. Can always get some awesome views then if the seeing is ok and improving at times, or just great seeing.

But yes, it was definitely a bad night of conditions in your case. It happens quite often, you think your scope is malfunctioning. You easily confirm for yourself it was the seeing the following night out.

Edited by Procyon, 29 May 2019 - 06:17 PM.

  • rkelley8493 likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics