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christheman200
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Reged: 06/12/13

Loc: Toronto, Canada
What to expect of Jupiter?
      #6028606 - 08/16/13 06:24 AM

Today and yesterday I stayed up very late to see Jupiter in the morning. In my ES 82 8.8mm it looks super crisp and sharp, but not very detailed. It appears to be about the size of Saturn's disk right now, and I can really only discern two bands and that's it. It seems like there is some deviation across the top band. This was expected. However, when I push it to 340x with my ultima barlow it loses almost all of it's detail, and even the bands are hard to make out. This is odd because seeing was great, no wind no nothing. Jupiter was about 35 degrees up (a rough guess). Is this to be expected? Or is my barlow deteriorating the view? Could it also be other parts of the optical chain not being up to snuff? This was all through my XX12i, and of course it will be greatly affected by seeing. I might try out a friend's 4mm and see how it fairs against my barlow, as we have an RASC meeting tonight and what looks to be the best viewing night of the year on Sunday. Thanks.

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brianb11213
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Re: What to expect of Jupiter? new [Re: christheman200]
      #6028638 - 08/16/13 07:20 AM

Jet stream? Collimation? Don't blame the optics until you have proof ...

... having said that x340 is waaay too much for Jupiter, which never does stand magnification well: 20x - 25x per inch is the realistic limit and 15x per inch usually works better.


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azure1961p
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Re: What to expect of Jupiter? new [Re: brianb11213]
      #6028666 - 08/16/13 07:54 AM

Sounds like a thermal or collimation issue with the scope. As a general rule as noted 25x per inch is a good general working magnification. In inspecting the smallest features like spots, barges, etc you may find 350x profitable if the sky allows it. With my 8" between 173x and 250x is the usual envelope. If the details are at the diffraction limit of your scope then you'll need more mag to define it.

At anyrate sounds like either your mirror was yet equalized to the outside temps or your collimation was askew.

Pete


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MikeBOKC
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Re: What to expect of Jupiter? new [Re: azure1961p]
      #6028727 - 08/16/13 08:49 AM

Jupiter is especially vulnerable to factors like seeing, scope cooldown and collimation. It's just a very persnickety target probably because there is just so much detail there, and when any factor is a bit off that detail suffers. It will get better as it gets higher in he sky, and now and then you will get a night when it just jumps out at you with startling clarity. I agree -- lower magnifications than you use on Saturn will yield better views. And check for Jovian moon transits; watching one is a great way to train your eyes for picking out maximum detail on Jupiter.

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christheman200
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Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: MikeBOKC]
      #6029505 - 08/16/13 04:32 PM

I did double check my collimation and it was spot on, but I was using my collimation cap so it might not be as accurate as I could hope. No jet stream last night, just still air. The scope had been outside for around 2 hours with the fan on so it should have cooled off. Maybe some dew could have been doing it? I checked it for dew, but there might have been a thin layer avoiding my eyes. There's also getting to be a lot of dust on the mirror now. But it didn't feel like it was the fact that I was pushing it too far, it really felt like the barlow was softening up the images way too much.

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christheman200
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Reged: 06/12/13

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Re: What to expect of Jupiter? new [Re: christheman200]
      #6029624 - 08/16/13 05:42 PM

I've compiled an imgur album of my primary and secondary mirror, main eyepiece and barlow lens. http://imgur.com/a/SsPlv#0 I've only had the scope for a month and there is a lot of dust on the primary, very little on the secondary. I have eyelash oils that keep coming back on my main eyepiece, and there are two streaks of some sort of residue left over from cleaning the barlow. Should I clean my primary? Can you see anything that would affect the seeing?

Edited by christheman200 (08/16/13 05:45 PM)


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brianb11213
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Re: What to expect of Jupiter? new [Re: christheman200]
      #6029653 - 08/16/13 06:01 PM

Jet stream is not apparent at ground level, unless you're on top of a 8000 metre mountain ... the air can be completely still at ground level & still have a 200 mph turbulent river of air at the tropsphere completely smearing the image. (Stars won't focus to better than a fuzzball; I've know jet stream smearing be so bad that it was nearly impossible to focus an 80mm scope at only x24.)

Dirt on the primary mirror is very unlikely to have any effect at all on the image. Just a slight reduction in contrast, if really awful. Cleaning the primary is probably the last thing to attempt.

Smearing is more likely to result from excess cleaning than too little. Having said that if you have visible smears on barlow / eyepiece do try cleaning the surfaces using isopropyl alcohol or similar to decontaminate, then dry with a very soft cloth, dabbing rather than scrubbing at the surfaces.


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christheman200
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Reged: 06/12/13

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Re: What to expect of Jupiter? new [Re: brianb11213]
      #6029706 - 08/16/13 06:27 PM

Thanks, I will try that cleaning method soon. There was no noticeable rippling even under high power, which is normally quite noticeable when viewing Saturn in the evening at such low elevations. Jupiter's moons also snapped into perfect focus. Even Mars looked rather good, other than a bit of fringing from it being so low. I don't think I've ever seen my scope give me images as still as yesterday.

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christheman200
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Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: christheman200]
      #6030380 - 08/17/13 06:44 AM

Now it is somewhat apparent that I did screw up my collimation, at least I think I did. My secondary was way off in the back/forth direction that you adjust with a screw. I now hope that it is somewhat more centred. It looks much more circular and seems centred. The collimation locking screws on the back are a bit odd in that to get them tight enough to stop the collimation from changing as I move the scope the collimation shifts. This means that by locking down the screws my collimation gets thrown slightly off and I have to pre adjust for this. I don't know if this is normal or what but I will look into it over the next couple of days. I got the collimation adjusted and let the scope completely cool down, luckily there was no dew today! I had my blow dryer prepared just in case. Anyways, today I spotted the GRS with and without the barlow. The images were dead sharp, although I'm itching to get myself a laser collimator to make them even sharper! 90 percent of the time I had perfect viewing with no turbulence and occasionally it was a bit hard to spot much detail. As the GRS came closer to the centre of Jupiter it became more and more obvious and pronounced, as well as becoming much more detailed. Detail in the bands was obvious. I can't wait until opposition! I did a pen on paper sketch but it shows the GRS very inaccurately (too large, this happened because at the beginning of my viewing session I thought the GRS included a whiteish area around it, but this seems to be a vortex surrounding it) and the sketch is not very detailed. For tomorrow I will get out my sketching pencils and might post my results!

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christheman200
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Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: christheman200]
      #6030382 - 08/17/13 06:49 AM

Also, as an alert to anyone who wishes to observe a transit, Io will be transiting tomorrow from 7:50 until 10am GMT, or 3:50 until 6am EST. I plan on sketching this too.

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Asbytec
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Reged: 08/08/07

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Re: What to expect of Jupiter? new [Re: christheman200]
      #6030394 - 08/17/13 07:01 AM

I look forward to your sketch.

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idp
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Reged: 08/21/09

Loc: New Haven, CT
Re: What to expect of Jupiter? new [Re: Asbytec]
      #6031129 - 08/17/13 02:45 PM

From your description, and in spite of the collimation problem you mentioned, I'd say there likely was a thermal issue. Did the telescope stay out all night long, or did you take it out right before observing?

When I observed Jupiter with my 8" newton, I could not see much during the first 1/2 hour or so. The situation improved greatly as the mirror cooled down, and after about 1 hour it was good to go.

Ivano


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christheman200
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Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: idp]
      #6031315 - 08/17/13 04:30 PM

The telescope had been out for a while, I'd say an hour to two hours, but that might not have been enough. It was a rather cold day now that I think of it. Tonight is supposed to be the best viewing of the year and I think we'll be heading off to a dark sky site with club members. As long as others want to show up I think someone can bring a good laser collimator and get my scope into perfect alignment. At least the secondary adjustments will last a long time, if not the back and forth position for years. I wonder what Saturn will look like with a properly collimated scope now? Also, do you know of any links to people who have had trouble with their collimation locking screws changing the collimation and how they fixed it? Thanks.

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christheman200
sage


Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: christheman200]
      #6031557 - 08/17/13 06:53 PM

I might also have a go at Saturn with the hopefully properly collimated scope. I completely disassembled the OTA and put together the mirror holder again, it now collimates properly without hassle. I also adjusted the secondary and I think it's about as good as I am going to get it.

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Sarkikos
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Re: What to expect of Jupiter? new [Re: christheman200]
      #6032028 - 08/18/13 12:07 AM

Chris,

Here's some ideas to improve your results with Jupiter (or other planets):

(1) Make sure your scope is very closely collimated. IME, the usual laser collimator and collimator cap does not cut it. Better to use a simple Cheshire/sight tube followed by an autocollimator. Stack the donuts.

(2) On a night of good seeing, after closely collimating the scope, test it on Polaris (or a similar star if you have tracking). There's no sense expecting too much on planet observation if there are problems with the optics.

(3) Allow time for the primary to adjust to the outside temps before you make critical observations. An hour is probably about right for a 12" mirror. Have a fan under the primary.

(4) Make sure the clips on the primary are not too tight. This can produce pinched optics.

(5) Try to set up your scope on grass, not on concrete or asphalt, to reduce local thermals from the ground. Placing outdoor carpeting under the scope can help.

(6) Think about getting a binoviewer. This can increase contrast, making planet surface detail easier to see.

(7) Construct an apodizing mask. Another way to enhance contrast.

(8) Use a Baader Moon & Sky Glow filter. IME, the best all around contrast filter for planets.

(9) Try to keep your eyes close to photopic adaptation. This will ensure your eyes are at their highest visual acuity (contrast, detail, color range). Keep a bright white light on near your scope (just don't have it glaring directly into your eyes or the telescope) or periodically look at a white paper illuminated by a bright white-light flashlight. A dark site is not necessary - or even preferred - for observing planets. But if you're at a dark site with other observers, you shouldn't do the "white light trick." This is a good reason to observe planets at home instead.

(10) Use just enough magnification to see the most detail with the best contrast. Pushing the power too much will make it more difficult to tease out fine surface detail, especially for Jupiter. You won't get a gold star for super high magnification.

Mike


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T1R2
Carpal Tunnel


Reged: 06/11/13

Loc: NeverWhere, 35*N
Re: What to expect of Jupiter? new [Re: Sarkikos]
      #6032142 - 08/18/13 02:01 AM

Chris, I stayed up until 5:30am and Jupiter was at about 45*, It was not steady and was a blur, my scope is critically collimated, with the jet stream this far south it will be hard for anybody down this way to get a good view until probably this fall and winter when it's higher earlier, in my C11, even when the air is still, views are almost photogenic at 233x (12mm) and is about the highest mag I use. My 5" didn't give very good views either when the planet is low, if you can rule out poor collimation, tube currents, then its probably the alt. and the jet stream.

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christheman200
sage


Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: T1R2]
      #6032150 - 08/18/13 02:15 AM

Where are you from? It was incredibly steady last night.

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christheman200
sage


Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: Sarkikos]
      #6032167 - 08/18/13 02:31 AM

Quote:

Chris,

Here's some ideas to improve your results with Jupiter (or other planets):

(1) Make sure your scope is very closely collimated. IME, the usual laser collimator and collimator cap does not cut it. Better to use a simple Cheshire/sight tube followed by an autocollimator. Stack the donuts.

(2) On a night of good seeing, after closely collimating the scope, test it on Polaris (or a similar star if you have tracking). There's no sense expecting too much on planet observation if there are problems with the optics.

(3) Allow time for the primary to adjust to the outside temps before you make critical observations. An hour is probably about right for a 12" mirror. Have a fan under the primary.

(4) Make sure the clips on the primary are not too tight. This can produce pinched optics.

(5) Try to set up your scope on grass, not on concrete or asphalt, to reduce local thermals from the ground. Placing outdoor carpeting under the scope can help.

(6) Think about getting a binoviewer. This can increase contrast, making planet surface detail easier to see.

(7) Construct an apodizing mask. Another way to enhance contrast.

(8) Use a Baader Moon & Sky Glow filter. IME, the best all around contrast filter for planets.

(9) Try to keep your eyes close to photopic adaptation. This will ensure your eyes are at their highest visual acuity (contrast, detail, color range). Keep a bright white light on near your scope (just don't have it glaring directly into your eyes or the telescope) or periodically look at a white paper illuminated by a bright white-light flashlight. A dark site is not necessary - or even preferred - for observing planets. But if you're at a dark site with other observers, you shouldn't do the "white light trick." This is a good reason to observe planets at home instead.

(10) Use just enough magnification to see the most detail with the best contrast. Pushing the power too much will make it more difficult to tease out fine surface detail, especially for Jupiter. You won't get a gold star for super high magnification.

Mike




All I have for now is the included collimation cap, which needless to say does not suffice. If it stays clear tonight I will star test on Polaris. Time will be allotted to cooling down the scope. I'll check if the clips are too tight. Setting up on grass really isn't much of an option. After spending so much money on everything so far a binoviewer is not what I need to spend my money on. I might make an apodizing mask some day. Maybe someday I will dabble with filters. There is already a lot of light around. Currently I can either go with 170x or 340x and that's it.


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christheman200
sage


Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: christheman200]
      #6032332 - 08/18/13 06:21 AM

Well, seeing started off good tonight, some of the best seeing in a long time. Saturn looked much better than I have seen it through my scope before, and I decided to take it to a dark sky site about 40 minutes away. Little did I realize/remember just how bad a nearly full moon would be on the seeing! We decided to just head straight home. I set up the scope at around 3:30 to cool down and headed out at 4:30 till right now. Jupiter did not look particularly good today, I think the seeing trailed off from being great to poor around 2am. The only real detail visible was Io's shadow, plus the two cloud belts and nothing else (other than three moons). I mistook Europa for Io until I took a look online as to where Io was, finding that it was over Jupiter's disk. I could not resolve Io against Jupiter's surface, but I might have been able to if I knew where to look. I should be ordering a glatter laser and tublug soon and will see how this affects my collimation accuracy/viewing. I won't adjust the mirror clips until I get the collimator so that I can make sure that I have the same collimation when testing to see if the tension was pinching the mirror. There was some fringing along the edge of Jupiter indicating atmospheric distortion, I have never seen it so bad at an angle of 35-45 degrees, at least I don't remember. Since there wasn't much to draw, I decided to just view. I drew Saturn, and it turned out well but I will hold off on posting that until I get a nice sketch of Jupiter. I also drew Venus but that wasn't very interesting.

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Sarkikos
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Reged: 12/18/07

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Re: What to expect of Jupiter? new [Re: christheman200]
      #6032722 - 08/18/13 12:00 PM

Quote:

I'll check if the clips are too tight.




You should be able to slip the edge of a business card between a clip and the mirror. If it's tighter than that, it's too tight and might pinch the primary.

Quote:

Setting up on grass really isn't much of an option.




So, exactly what do you mean by this? There is no grassy area on which you can set up the scope or there is? Sometimes idioms don't make immediate sense to me unless there is further explanation.

Setting up on concrete or asphalt is not a good idea, especially if you're going to view planet/lunar. Those materials store heat during the day and will release it throughout the night. If you must put the scope on asphalt/concrete, throw a couple outdoor carpets down first.

Quote:

There is already a lot of light around.




That is good for viewing planets, unless the glare goes directly into your eye or the telescope. But you may be overestimating the brightness of the ambient light. If it's not as bright as a bright white-light flashlight, it's not bright enough. Try the flashlight trick.

Quote:

Currently I can either go with 170x or 340x and that's it.




170x will only be 14x per inch. You should be able to go higher than that for planets. 340x is 28x per inch. That should be plenty if the seeing is at least fair. If you are consistently keeping your eyes near photopic, you might not need to go any higher - assuming good seeing - to see fine surface detail.

Mike


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