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christheman200
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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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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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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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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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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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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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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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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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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
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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
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Reged: 06/11/13

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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
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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
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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
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Reged: 06/12/13

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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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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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Sarkikos
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Re: What to expect of Jupiter? new [Re: christheman200]
      #6032747 - 08/18/13 12:12 PM

Quote:

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.




You don't need to go to a dark site for viewing planets! If you're just going to look at planets or the Moon, you can stay home.

It shouldn't matter if the Moon is nearly full or not if you're observing a planet, unless maybe the Moon is right next to the planet in the sky. Planets are not like deep sky objects. These are completely different animals. You need a dark site and a moonless night for DSO, but not for planets.

Also, the Moon has absolutely no affect on the seeing. Seeing is the level of turbulence of the atmosphere. But the Moon will limit how deep you can go, what will be the faintest objects you can see.

Quote:

I should be ordering a glatter laser and tublug soon and will see how this affects my collimation accuracy/viewing.




These are good tools but more than you really need. A simple Cheshire/sight-tube followed by an autocollimator will do just as well if not better. The advantage to the Glatter laser and Tublug is that you can collimate in the dark with them.

Mike


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Sarkikos
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Re: What to expect of Jupiter? new [Re: Sarkikos]
      #6032752 - 08/18/13 12:14 PM

In Maryland, we often enjoy better seeing during summer and fall. Winter and spring are usually worst for seeing here.

Mike


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christheman200
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Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: Sarkikos]
      #6033326 - 08/18/13 06:02 PM

Quote:

Quote:

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.




You don't need to go to a dark site for viewing planets! If you're just going to look at planets or the Moon, you can stay home.

It shouldn't matter if the Moon is nearly full or not if you're observing a planet, unless maybe the Moon is right next to the planet in the sky. Planets are not like deep sky objects. These are completely different animals. You need a dark site and a moonless night for DSO, but not for planets.

Also, the Moon has absolutely no affect on the seeing. Seeing is the level of turbulence of the atmosphere. But the Moon will limit how deep you can go, what will be the faintest objects you can see.

Quote:

I should be ordering a glatter laser and tublug soon and will see how this affects my collimation accuracy/viewing.




These are good tools but more than you really need. A simple Cheshire/sight-tube followed by an autocollimator will do just as well if not better. The advantage to the Glatter laser and Tublug is that you can collimate in the dark with them.

Mike




I went to a dark sky site after Saturn had set. We were going to go for some DSO observing, and honestly half of the sky wasn't too bad so we could have stayed but there were others that were supposed to come and none did, so it wasn't worth staying. By seeing I meant light pollution from the moon affecting viewing, I guess that word isn't really appropriate. I generally collimate once or twice while I'm outside and I don't want to have to shine a flashlight down the tube to do it. It's more expensive but it's worth it.


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wfj
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Re: What to expect of Jupiter? new [Re: christheman200]
      #6038472 - 08/21/13 02:39 PM

You don't need to shine a light to collimate - simply look at a bright star (or Polaris if you'd like it to not move) and tweak to perfection.

Planetary is all about constant practice / repetition. You do this enough times, with best performance learned out of equipment and tweaking and skill, that when good seeing happens, it all comes together.

It's hard to have expectations met, because many things not under your control can go wrong. It might be a better strategy to not have expectations but to improve skills incrementally - not likely to come all at once.

Jupiter is a highly dynamic planet - from the last few mornings I've observed it, this pass is already showing a different story than last year. With my modest equipment/skills, watching the "fluid dynamics" of GRS passage, the combination/split of other spots, the short lived activity along the equator all exceed my expectations on a weekly/monthly basis.

Suggest along with Mike that you observe from home - to increase frequency. Also DSO's and Jupiter are "night and day" different - I keep them on separate schedules.

Here's to a nice Jupiter, then Mars, then Jupiter ... observing season.


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Sarkikos
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Re: What to expect of Jupiter? new [Re: wfj]
      #6038930 - 08/21/13 06:44 PM

Quote:

You don't need to shine a light to collimate - simply look at a bright star (or Polaris if you'd like it to not move) and tweak to perfection.




Agreed ... but not so much to perfection. IME a closer collimation than checking the diffraction pattern of a star can be reached by using a Cheshire/sight-tube and then stacking the donuts with an autocollimator. Unfortunately, that combination needs a fairly bright source of light.

When I'm observing planets at home, I collimate my solid tube 10" Dob inside the house before I set it up outside. If I'm going to a dark site, I collimate at home before I leave. I try to get there while there's still some light in the sky so I can tweak the collimation, just in case it was loosened in transit. If I arrive well after sundown, I'm out of luck. I don't have the tools to collimate in the dark. Then I would have to check the diffraction pattern of Polaris.

It gets complicated with a truss scope, which needs to be put together again everytime it's used. It needs to be collimated every time on site after it's fitted together. There's no getting away with a little tweak to the collimation, as with a solid tube scope.

In any case, if you set up the truss scope either at home or at the dark site while there's still some light in the sky, you don't need an artificial light for collimation. This would also allow the scope's optics plenty of time to cool.

If I were to buy a truss scope, though, I think I'd be sure to get a good collimation kit - maybe the Glatter laser and Tublug - that can be used after dark. I wouldn't want to arrive after dark at a remote site and have no way to collimate my truss scope. That would not be good.

Mike


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christheman200
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Reged: 06/12/13

Loc: Toronto, Canada
Re: What to expect of Jupiter? new [Re: Sarkikos]
      #6042969 - 08/24/13 04:50 AM

I'm picking up a glatter/TuBlug, and I will also need to solve my collimation locking problems before it arrives.
I didn't notice this before, but it now seems that my collimation locking screws aren't doing there job.
Cranking them all the way down, it still shifts when I move up and down, and this is a substantial shift.
I think I will need to install tougher springs to stop this issue, it should make the locking screws useless.


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corpusse
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Reged: 04/11/10

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Re: What to expect of Jupiter? new [Re: christheman200]
      #6043348 - 08/24/13 10:48 AM

I only image, so I'm not quite sure why I'm reading this thread, but I'd like to point out the seeing in Mississauga is usually terrible to fair. Last year I did not get one real good Jupiter image despite trying many times. I got one good Saturn this year (the low alt didn't help).

I'm not really sure why but real good seeing seems to be very rare here.


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dscarpa
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Re: What to expect of Jupiter? new [Re: Sarkikos]
      #6043793 - 08/24/13 03:15 PM

On Friday we at long last had clear skies at dawn and got my first look at Jupiter this season. Seeing was good and I was using a 5 XO and 7 XW barlowed to 175X-240X in my WO ZS-110. The two main belts and 3 others were sharp with a little detail and the polar hoods were easy to see. Europa, Ganymede and Callisto were the moons seen. In San Diego County seeing for lunar-planetary is often better on the coast than in the mountains or desert. David

Edited by dscarpa (08/24/13 03:24 PM)


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dscarpa
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Re: What to expect of Jupiter? new [Re: Sarkikos]
      #6043809 - 08/24/13 03:24 PM

On Friday we at long last had clear skies at dawn and got my first look at Jupiter this season. Seeing was good and I was using a 5 XO and 7 XW barlowed to 175X-240X in my WO ZS-110. The two main belts and 3 others were sharp with a little detail and the polar hoods were easy to see. Europa, Ganymede and Callisto were the moons seen. David

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Special Ed
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Re: What to expect of Jupiter? new [Re: dscarpa]
      #6044033 - 08/24/13 06:20 PM

@ the OP,

There are already a lot of good pieces of advice about observing Jupiter in this thread so I'll try not to repeat them. An altitude of 35 is still pretty low and will definitely affect your ability to see detail in Jupiter's cloudtops, all other variables being equal.

The important thing is to keep trying. The good news is as the apparition progresses, Jupiter's altitude will increase. Now is the time to start training your eye to see detail. I was glad to read that you sketch--that's probably the best way to train your eye and sharpen your observing skills.

I suggest you sketch your observations even if you can't see any more detail than the 2 main belts. As time goes on, you will be surprised how much detail will reveal itself and your sketching skills will benefit from the practice as well.

Another suggestion--as far as magnification is concerned, the sweet spot for Jupiter is often 200x-260x. From your report, that is exactly the hole in your eyepiece collection. If your budget is tight, maybe you can borrow an ep from a friend in RASC that will yield that range in your scope. BTW, that 12" scope should provide you with some fine views of the King and the larger aperture makes color easier to see, in my experience.

Good luck with your Jupiter observations and please share your sketches here and/or in the Sketching Forum.

@ dscarpa--congratulations on your first look this apparition and thanks for the report. Jupiter is never the same from one apparition to the next--looking forward to my own first look.

Best regards to all.


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Re: What to expect of Jupiter? new [Re: christheman200]
      #6045227 - 08/25/13 01:46 PM

I find that to be the sweet spot power wise for Jupiter as well. View at dawn. Last night my ZS was only pulling in 2 fuzzy belts when it wa low. Later on it was 5 belts and 3 moons but no spot. Next session my IM-715 or C9.25 is going to get a crack at it. David

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christheman200
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Re: What to expect of Jupiter? new [Re: corpusse]
      #6046379 - 08/26/13 03:55 AM

Quote:

I only image, so I'm not quite sure why I'm reading this thread, but I'd like to point out the seeing in Mississauga is usually terrible to fair. Last year I did not get one real good Jupiter image despite trying many times. I got one good Saturn this year (the low alt didn't help).

I'm not really sure why but real good seeing seems to be very rare here.




Yeah, we normally have *BLEEP* weather here, but we've had a decent stretch for the past two weeks.
I haven't been able to make a sketch yet because of bad turbulence for the last while.


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christheman200
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Re: What to expect of Jupiter? new [Re: Special Ed]
      #6046380 - 08/26/13 04:00 AM

Quote:

@ the OP,

There are already a lot of good pieces of advice about observing Jupiter in this thread so I'll try not to repeat them. An altitude of 35 is still pretty low and will definitely affect your ability to see detail in Jupiter's cloudtops, all other variables being equal.

The important thing is to keep trying. The good news is as the apparition progresses, Jupiter's altitude will increase. Now is the time to start training your eye to see detail. I was glad to read that you sketch--that's probably the best way to train your eye and sharpen your observing skills.

I suggest you sketch your observations even if you can't see any more detail than the 2 main belts. As time goes on, you will be surprised how much detail will reveal itself and your sketching skills will benefit from the practice as well.

Another suggestion--as far as magnification is concerned, the sweet spot for Jupiter is often 200x-260x. From your report, that is exactly the hole in your eyepiece collection. If your budget is tight, maybe you can borrow an ep from a friend in RASC that will yield that range in your scope. BTW, that 12" scope should provide you with some fine views of the King and the larger aperture makes color easier to see, in my experience.

Good luck with your Jupiter observations and please share your sketches here and/or in the Sketching Forum.

@ dscarpa--congratulations on your first look this apparition and thanks for the report. Jupiter is never the same from one apparition to the next--looking forward to my own first look.

Best regards to all.




I will definitely try to sketch all of my Jupiter observing sessions in the future!
Of course, the seeing got worse progressively after that one good night, so no sketch yet.
I'm looking at getting a 6mm when it is possible. I fear I've already asked around for too many things in my local RASC (mount, barlow, diagonal, you name it!).
However, a friend, Jo, may have an eyepiece I could borrow for a while but I don't want to bother anyone until our next viewing session.


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TG
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Re: What to expect of Jupiter? new [Re: christheman200]
      #6047122 - 08/26/13 02:38 PM

Quote:

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?




Jupiter, unlike the other planets, doesn't take power well. I've noticed that that an exit pupil of about 1mm gives the most pleasing view, large enough yet containing a lot of details. Higher powers will make the lower contrast features on Jupiter, such as ovals and festoons, harder to make out. I'm not sure why this is the case. It may be that the image dimming at higher powers causes the eye to lose its ability to discern low contrast features.

The power for a 1mm exit pupil is easy to calculate: it's the same as your aperture in mm.

If you know how to star test, do it just when you are observing Jupiter. It'll quickly tell you if everything is ok with your optical train. The things to watch for are seeing, collimation and thermals. If all three are ok, then you can worry about other possible problems.

Tanveer.


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Scott in NC
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Re: What to expect of Jupiter? new [Re: TG]
      #6049677 - 08/27/13 09:08 PM

Quote:


The power for a 1mm exit pupil is easy to calculate: it's the same as your aperture in mm.





And another easy to remember formula is that the focal length of the eyepiece needed to produce a 1mm exit pupil is the same length (in mm) as the f/ratio of your scope. E.g., an f/6 scope would need a 6mm eyepiece to give you an exit pupil of 1mm.


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Re: What to expect of Jupiter? new [Re: christheman200]
      #6050444 - 08/28/13 10:56 AM

Sunday AM the mak showed about the same as the ZS. This AM I had the 9.25 with a 10 XW for 260X and there was quite bit more detail including the GRS! That side of Jupiter does have more to see. As to the spot it didn't jump out at you but it was easy. David

Edited by dscarpa (08/28/13 10:58 AM)


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Re: What to expect of Jupiter? new [Re: christheman200]
      #6050452 - 08/28/13 10:58 AM

Sunday AM the mak showed about the same as the ZS. This AM I had the 9.25 with a 10 XW for 260X and there was quite bit more detail including the red spot! That side of Jupiter does have more to see. As to the spot it didn't jump out at you but it was easy. David

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Re: What to expect of Jupiter? new [Re: christheman200]
      #6054619 - 08/30/13 03:15 PM

This AM I was viewing Jupiter with my IM715 using a 12 Delos for 250X with very good conditions. All four different colored moons were there with Io's shadow black and sharp but rather small. The GRS was coming over the limb and 5 belts with quite a bit of detail in them and the polar hoods was visable! What to expect of Jupiter? It would appear to be a lot given good conditions! David

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Re: What to expect of Jupiter? new [Re: dscarpa]
      #6060128 - 09/02/13 10:15 PM

I have a post up in the reflector forum, but I might be able to get some help here too. It is now very obvious that my collimation locking screws are not doing anything or possibly making my collimation worse. No matter what I do the collimation drifts a LOT past 75 degrees up. Does anyone know of a possible fix? When I posted my thread originally, it was about shimming my mirror but it quickly turned into asking about my collimation locking problem. At first, I thought I had finally nailed the problem as a loose spider or secondary, but once that was dealt with it was clear that the mirror was drifting. I am using a collimation cap and once I get the dot centred at around 45 degrees, I tighten up the collimation locking screws. However, no matter how tight the locking screws get they do not stop the dot from drifting around 2-4 donut diameters across the surface of the mirror. Most drift is noticeable past 75 degrees upwards, with some noticeable past 25 degrees downwards. Any help is appreciated, thanks.

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