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Old 13-06-2010, 12:58 AM
Benboy (Ben)
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Is what I'm seeing normal?

Hi everyone,

I own a 6" Skywatcher Dob and have been learning a lot about astronomy/telescopes the last couple of months - especially from this forum.

I've been a bit disappointed with my views of saturn since I got my telescope and was wondering if I can get some advice on what could be the problem. I have the standard 25mm and 10mm skywatcher plossls that came with my scope -plus I just recieved a 6mm sterling plossl.(It's cheap but they get rave reviews).

All I see is a white circle with a perfectly flat-straight line going through it. I wasn't expecting much from the 25mm plossl and I heard the 10mm ones that come with scopes are normally terrible so I was putting it down to the eyepieces - both focal length and quality - or collimation. Now however I have a 6mm sterling plossl and all I see is the same but bigger- no colour, no details etc just a white circle with a flat line through it. I know the sterling plossl is not an expensive eyepiece but if you look them up they consistently get great reviews so now I am not sure what could be my problem.

As far as collimation goes I don't yet have a collimating tool (buying things one at a time because of my budget) and so I did consider that could be the problem - however I have just been looking up star collimating tests and what I see through my telescopes looks like what they say a collimated scope should see. So what could be my problem?
From what I have seen other people post of pictures taken through similar telescopes (i.e. not edited photos) and their comments about what they see - I should be seeing much better images...???

Sorry for the rant, any advice on where I should be looking would be greatly appreciated.

Thanks,
Ben
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Old 13-06-2010, 05:30 AM
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Stu Ward
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Ben
You are seeing exactly what you should, however with averted vision, and lots of practice you can pick out small details.
The ring is edge on atm, so you just see the flat line. When the our positions change it is possible to see more ring detail.
As for what you have seen on images, these are very long exposure pics, and probably computer enhanced, filtered etc.


Stu
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Old 13-06-2010, 08:29 AM
astro744
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The pictures you see are usually done with high speed CCD video cameras capturing AVI footage and then processed so that only the sharp frames are used and stacked to give the final image. You will notice the sharpest pictures are those from captured AVI footage and those from DSLR, although good cannot compete with the detail.

In the days of film exposure times for planetary imaging were in the order of a second or two (depending on many parameters) but they were never 1/30 or 1/60 sec. snaps. During the exposure the seeing had to remain steady which was not often the case. Visually though the eye could spot fine detail during brief fractional seconds of exceptional seeing giving the eye an advantage over photgraphy. Nowadays imaging has the edge over visual in the amount of detail that can be recorded. However nothing has changed for visual observing as you can still see an incredible anmount of detail given the right conditions and these conditions are:

1. A well collimated telescope which can be achieved with a star test and minimal tools.
2. A temperature stabilised telescope and eyepiece, (An hour of cooling for a 6" will make a big difference).
3. Exceptional seeing between you and the object with no turbulence in the atmosphere or within your local surrounds, eg. warm roof top or pavement giving rise to thermal currents.
4. A quality eyepiece (for planets only on axis performance matters if tracking is utilised).
5. Good eyesight and a trained eye for detail only achieved through experience.

Turbulent atmosphere and warm equipment are usually the main culprits to bad images and if your telescope is cooled but the atmosphere is not cooperating then either wait a bit or try another night.

Saturns rings are edge on but will open up over the next few years. The atmospehere of Saturn is bland compared to Jupiter but shaded bands can be seen although the colours are subtle. Either get up early and try Jupiter now or wait for Jupiter to move into our evening sky over the next few months.

Note transparency of the atmosphere is not so important for planetary observing and in fact good seeing can be achieved through hazy conditions. In fact a very dark sky can often be more turbulent especially if a cold front has recently passed.

Last edited by astro744; 13-06-2010 at 08:37 AM. Reason: Added note on transparency.
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Old 13-06-2010, 08:59 AM
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torana68 (Roger)
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Hi,
Try this for a comparison http://www.telescope-simulator.com/i...d=45&Itemid=57 , lots of things need checking, you should get a colimator (or borrow one) and check adjustment. I seem to remember my 4.5 did show a little deail so a 6 should but it really depends on the quality of the mirror and the eyepieces and then adjustment and the one you cant change "seeing", "seeing" is rarely perfect and you just have to get out there and look (there are videos on youtube taken through the eyepiece you can have a look at as well but youll have to search)
Roger
where's Suzy shes the 6" expert
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Old 13-06-2010, 09:44 AM
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Hi Ben .... yep, what the others have said.
I agree, Saturn is small through the EP at the moment, but this changes all the time. At the moment Saturn is heading away from Earth after opposition (closest to Earth) in March. As also said, the rings are pretty edge on at the moment at about 1.7' but will slowly increase. These 2 factors make for a smaller visual impact.
BUT .... this is still great through a scope - to see the planet and rings, even edge on is wonderful, and there should be a few Moons floating around too. www.stellarium.org to show the moons. Titan is easily visible.
Put in your 10mm and then the 6mm - take you time, make sure you are comfy (sitting on a stoll etc) take your time and soak it all in. Not just a 10 sec look.
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Old 13-06-2010, 06:49 PM
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Hi Ben,
I too have a 6” dob. And as Liz said, what you are seeing with Saturn at the moment is spot on. Back a few months (and leading up to) opposition (the point where Saturn and Earth are closest), parts of the black rings were easily detectable using a 7mm or 5 mm ep, and you could make out some shading bands of colour on the planet. I have also counted six moons with ease.

Though Saturn is always spectacular, it’s not great viewing at the moment – so much smaller than what it was and the rings edge on. The seeing conditions will dictate how much shading the bands on the planet will reveal. Some days I don’t see anything, some days I’ll be very happy with the detail I could see. For the days I don’t see a lot of detail, heck, I’m just happy I get to see Saturn anyway – how lucky are we! I have a 4mm Celestron ep, the hole to look through is not much bigger than a nail head (amazes me how much I can in fact see thru this little dot, but I do). The f.o.v. is very small for a dob, but I have used it plenty, though for short amounts of time (too much work, nudging dob), and it brings Saturn really close, the whole fov is nearly all planet. I can make out the banding better on this than on a 7mm. The weather hasn’t allowed me yet to try my barlowed 10mm down to 5mm, so I can’t comment at the moment on the abilities of this (a 5mm ep). With a dob, I much prefer to have wider fov’s (66 – 70 deg) so I can enjoy the object longer in my fov. And I do use this much more than my 4mm it’s true. But I still like to get that 4mm on, just for a quick look, before I start to get frustrated with nudging. As for viewing of the rings, I've found that a 10mm or a 7mm will give me easy views of them, including the black ones.

The next opposition of Saturn will be April 2011, (approx. every 13 months) the month leading up to during and after will be particularly spectacular. But don’t worry, Saturn’s rings will start to open up again soon. As Liz said, the rings at the moment are only 1.7 deg. The end of this month will see them open up to 2.1, July 3.2, Aug. 4.4, Sept. 6.1, Oct 7.8, Nov 9.3, Dec. 10.1 (Wow). The figures I have listed are for at the end of each month. As you will see in the following link, it shows you month by months how the rings will open up. //sites.google.com/site/larrygerstman/saturn-s-rings From October on, Saturn will look really amazing!

Jupiter is going to be in opposition in September. Though it is missing its south eq. belt at the moment, trust me through your 6” scope, using either a 10mm or a 5mm ep will give amazing views. It won’t disappoint. I saw it for the first time in Dec. 2009 when it was a lot smaller, and very low in the horizon, and it was still amazing! You will see the belting, and if you’re looking at this planet whilst it’s face is showing its red spot, you will just make that out as well. Here is a link showing all the transit times for the red spot for this year. The table is shown in Universal Time, so factor your time zone into this. And you will even see its four moons with ease.


Here is another link thay may be of interest to you as well - an Astronomy Calender of Events for 2010. http://www.seasky.org/astronomy/astronomy_calendar_2012.html.


If you are able to get a hold of the book Astronomy 2010 Australia, it will really be helpful for you. They sell for $25 (Ozscopes, Andrews - both online) many places that sell scopes will sell this book. It has a calender of info for each month, maps, and a ton of helpful information. Worth the money.


Ben, in the last six months that I’ve gotten into doing this hobby, I have noticed my eyes "see" so much more detail nowadays. Don’t just look at an object – study it, look at it for a long time (30mts for me at least is common), see as much as you can see, use techniques like averted vision, protect your night vision, etc. It probably took me three months (a whole lot of viewing within this time), before I really noticed how my eyes have gotten better, and continue to do so. So please, have patience, make yourself comfy, it will get better and you will enjoy this hobby more and more. You see, your eyes have to get trained, taking them to the limits of the scopes abilities. You will get there. The journey is the fun part, because it makes us want more and more.

As long as you have patience and a keen desire to learn and see more, the stars and planets will be there for a long time to come. Enjoy Ben!
Suzy.

Last edited by Suzy; 13-06-2010 at 10:18 PM. Reason: typo.
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  #7  
Old 13-06-2010, 07:58 PM
astro744
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Oppositions of Saturn 2009-2018:

Saturn 2009 Mar 8
Saturn 2010 Mar 22
Saturn 2011 Apr 3
Saturn 2012 Apr 15
Saturn 2013 Apr 28
Saturn 2014 May 10
Saturn 2015 May 23
Saturn 2016 Jun 3
Saturn 2017 Jun 1
Saturn 2018 Jun 27

At opposition Saturn's declination changed from from +6.68deg. in 2009 to +1.84deg. this year and will be -22.45deg in 2018 meaning it will be much higher in the sky in eight years. The planets diameter changes from 19.5arcsec to 18.4arcsec in the same time. The rings were edge on last year and will open to about 27deg. in about 7 years after which they will start to close again.

It is about 12.5 months between oppositions of Saturn and 13 months between oppositions of Jupiter.

Saturn will appear much sharper when it is higher in the sky and at say lattitude -40deg., 0deg declination is 50deg up from north horizon meaning in 2018, when Saturn's declination is -22.45, it will be 50+22.45=72.45deg. high from north when it transits. Currently at -40deg. lattitude it is transiting at 50+1.84=51.84deg. For each degree in latitude north Saturn will move a degree south and will be at zenith during transit at latitude -22deg. (approx. Rockhampton).

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Old 19-06-2010, 01:17 AM
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StellariuS (Jayden)
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I also use a 6" and most likely have similar views as you do. You got a Barlow? i have a 2x, and when i use it, Saturn loses a fraction of quality but covers more of my view. If you don't have a Barlow it might be worth giving it a shot. Don't let your scope disappoint you, just use it and learn its barriers and its strengths, there's way more out there other then Saturn. If a night just isn't working for me, I'll just point back to Carina (home turf) near the southern cross. Carina is crammed with magnificent views and never ceases to amaze me. You'll find your place.
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Old 21-06-2010, 07:54 PM
Benboy (Ben)
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Wow, thanks guys!!

I'm really glad I posted that question - lots of helpful information. Good to get confirmation of what I am seeing. I was aware of the "processed" photos as I mentioned, but still had the impression there was more to see. The info in this thread about angle of the rings - how close it is to earth etc would go some length to explain that. Also I have had some much better looks in recent days - or maybe it's just my "eye" getting better. But I agree that it is impressive just being able to see it like that at all - but it sure is helpful to know that what I am seeing is about right.
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