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How can I see larger views of planets

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#1 bfeeney

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Posted 17 August 2019 - 11:00 PM

Hi everyone. My name is Brian, I'm new here and new to astronomy, glad to be part of a forum for my new found hobby. I have a 120 x 1000mm reflector telescope my wife and I take out onto our back deck to look at the planets. I recently bought some middle-of-the-road Svbony wide angle eyepieces (10, 15, 20 & 23mm) to get away from the cheapy ones that come with the scope. We look at Jupiter and Saturn a lot, and they look cool, but they're small, especially Saturn. I start with the 20mm or 23mm to find the planets then work down to the 10mm to zoom in, but even with the 10mm the planets are rather small. We can see that Saturn has rings, but that's about it. I think I max out the scope with the 2x barlow and the 10mm. My question is, how do I get a larger view of the planets? Is it eyepieces? Mirror Diameter? Focal length? All of the above? I know 120mm isn't huge but it's a big step up from my 70mm travel refractor. I'm thinking about getting a used 12" Dob down the road, but I want to get the right one. Thanks everyone.


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#2 petert913

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Posted 17 August 2019 - 11:07 PM

Well, Saturn is almost a billion miles away. So unless you have a 14” SCT, she’s gonna be a bit on the small side lol.gif


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#3 Jim Waters

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Posted 17 August 2019 - 11:18 PM

Get a 14 or 16" f/4.5 plus DOB with above average optics and use high-power eyepieces.  


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#4 astro_1

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Posted 17 August 2019 - 11:22 PM

Yep, focal length is what you need. That is followed by more aperture. 



#5 bfeeney

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Posted 18 August 2019 - 12:03 AM

Thanks for the quick response everyone. Yeah, I figured I need a bigger scope, I didn't think I would need a 14"+ though. From what I've read, I gathered that 8" is good, 10" is better & 12" is where it's at, before the prices skyrocket and portability is diminished. I'll probably end up with a 12" unless I find a good deal on something larger.

 

Any suggestions on good eyepieces (that aren't $250 each)? I debated on wide angle or Plossl and ended up going with the wides. While they aren't top of the line, I can definitely tell a difference.



#6 Sketcher

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Posted 18 August 2019 - 12:50 AM

Many people don't like to hear this, but it takes practice (among other things) to really "see" planets (or any other astronomical objects) through a telescope.

 

If I understand your post correctly, your telescope has a 120mm aperture -- that's large enough to reveal quite a bit of detail on Jupiter and Saturn.  Furthermore, your telescope has a 1,000mm focal-length.  You can achieve the following (and more) magnifications, assuming you can use the 2x Barlow with any of the eyepieces you've mentioned:

 

23mm eyepiece -- 1000 divided by 23 provides a magnification of 43x

20mm --- 50x

15mm --- 67x

10mm --- 100x

15mm + Barlow -- 133x

10mm + Barlow --- 200x

 

That's a reasonable range of magnifications for a 120mm telescope.

 

While Jupiter and Saturn don't look particularly large at 100x, 133x or 200x, those magnifications are sufficient to reveal quit a bit of detail -- under good enough sky conditions (all nights are not equal in this regard) once the observer has gained enough experience.

 

Frankly, you don't really need to see larger views of the planets.  You need to take your time and look for finer details in the images that you do see.  Even then, it will take time (days, weeks, months, and yes, even years) to develop your observational skills through practice, practice, and more practice.

 

There's much to learn about using a telescope.  It's not just a simple matter of pointing a telescope and instantly seeing all there is to see of any targeted object.

 

If I manage to get around to it I'll take a photo (and post it here) of a painting I made in 2001 that shows the details that were seen on Jupiter and Saturn with a 80mm f/5 achromat refractor operating at a magnification of 105x.

 

On the other hand, if what you really want is just a larger view, you can get that by using a shorter focal-length eyepiece (such as a 6mm, 4mm, or 3mm) and/or a stronger Barlow (such as a 3x or 5x); but trust me, going that route will not reveal more planetary detail.  It'll make the planets look worse -- bigger, but dimmer and fuzzier.  A bigger image isn't always better.

 

Another solution is to go out and buy a larger telescope, but that too would be a mistake.  It's much better to learn how to "see" using a smaller telescope before jumping onto the larger telescope bandwagon.  Some things are just easier to learn while using smaller telescopes.  Besides, atmospheric conditions and other issues can make a large telescope (at times) no more effective than a smaller telescope.


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#7 aa6ww

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Posted 18 August 2019 - 01:02 AM

 Don't believe it Brian. You have an excellent telescope for observing both Jupiter and Saturn and even the deep space objects.

120mm of aperture at F/8.3 is plenty of aperture to give in incredible views of both of these planets, but you have to do the homework.

 

Don't be "that guy" that keeps buying scopes without first understanding how to use what you have effectively. 

 

 

First of all, you have to make sure your optics are perfectly aligned. Follow the procedures, find some video's on YouTube, and ask in the reflector forums out here if you get confused on how to align your optics. Its not a big deal,  you just have to know how to do it right.

More importantly, you have to understand a few basic facts about how to optimizing your planetary observing. Your scope has to be full acclimated to the outside conditions. You cant just take your scope outside on any given night and set it up and expect it to give you jaw dropping views of the planets.   

You are going to have to leave your scope out for at least half an hr, maybe an hr, before everything should be full acclimated. The tube currents and temperatures inside your scope has to be acclimated to the outside temperatures. This should take some time. An hr should be plenty of time for a 5" mirror and 120mm tube.

These are all things you have control over, which I have mentioned above.

 

Now you have to understand seeing conditions. Read up on "Seeing conditions" and how they effect your planetary observing. Do the homework. Get online and start googling  what I just said. 

What you will find out is that 80 percent or more of your ability to observe planets successfully will be completely out of your control because you need good to excellent seeing conditions to really bring out the best of planetary observing.

 

Find the closest city to where  you live using this site:

 

 http://www.cleardark...html#chart_list

 

and look at the chart for your area and wait till seeing conditions are 4/5 at least, or better. At 3/5 conditions, you wont be able to get very high in magnification before the planets soften up and you loose sharpness.

 

From that site i just sent you on seeing conditions:

 

"The line, labeled Seeing, forecasts astronomical seeing. (It's an experimental forecast.) Excellent seeing means at high magnification you will see fine detail on planets. In bad seeing, planets might look like they are under a layer of rippling water and show little detail at any magnification, but the view of galaxies is probably undiminished. Bad seeing is caused by turbulence combined with temperature differences in the atmosphere. This forecast attempts to predict turbulence and temperature differences that affect seeing for all altitudes.

Bad seeing can occur during perfectly clear weather. Often good seeing occurs during poor transparency. It's because seeing is not very related to the water vapor content of the air."

 

So its a waiting game. Pick your nights of favorable seeing conditions. The most knowledgeable astronomers are also very good at meteorology because we need to understand the skies and how it reacts to our observing needs to make the most of not only planetary observing, but also of deep space observing.

 

For the record Brian, this year has been one of the worse years ever for me, in California, for favorable seeing conditions. Your area could be completely different. This year alone, to the best of my knowledge, we have had one night of excellent seeing conditions. 5/5 based on the clear sky clock. One night only for this entire year.

So don't beat yourself up thinking you need a better scope, because you don't. Proper seeing conditions is the key to your successful planetary observing.   

Also, for this season of both Jupiter and Saturn, both planets are very low in the sky this year, so you are also having to look through the lower layers of muck and garbage low in the atmosphere compared to other years where the planets are positioned higher in the sky where the atmosphere is cleaner and the observing is better. 

 

Seeing conditions is the key to successful planetary observing, and unfortunately if you just plan to do back yard observing, you are at the mercy of the Gods ability to give you calm stable conditions.

 

You can take your scope to higher altitudes, I did this 3 weeks ago and it made a world of difference in the seeing conditions and my planetary observing. I went to a local star party at an altitude of 5200 feet in elevation. Normally, my back yard is at about 30 feet in elevation so theirs is a world of difference. Again, your situation could be completely different so its best to know your situation there, or ask others about your area, city, etc on how to get the most out of your planetary observing for your particular area. You may also have a local astronomical society which would help you immensely and they may have some nice locations you can observe at also, as a group.

 

Everything I mentioned above is just common knowledge about general planetary observing and optimizing your planetary experience.

 

Regarding your eyepieces,

 

10mm at 1000mm FL is 100x  with a 2x barlow is 200x

15mm at 1000mm FL is  67x   with a 2x barlow is 134x

20mm at 1000mm FL is  50x   with a 2x barlow is 100x

23mm at 1000mm FL is  43x   with a 2x barlow is  86x           

 

from my experiences, you should be able to get decent planetary views with 3/5 seeing conditions up to maybe 134x. It would be hit and miss but if your scope is fully acclimated and your optics are aligned properly, you should get both Saturn and Jupiter to look pretty good at 134x as your upper magnification. Go back and forth between 100x and 134x, see what works best. Use your 20mm with a barlow for 100x instead of  your 10mm eyepiece.

 

If the seeing improves and you have better conditions, 134x should be very crisp where you should be able to see festoons on Jupiter and nice views of the Great Red Spot. Also, some nice shadow transits of Jupiter's moons should come through nicely.

 

On Saturn,  you should be able to see the Cassini division come in and out at 134x at 3/5 seeing conditions. Drop the magnification down to 100 and see if the sharpness improves. Use your 20mm with a barlow for 100x instead of  your 10mm eyepiece. 

 

With 4/5 seeing conditons, check the Clear Sky Chart for your area, 134x should be awesome with your 120mm reflector for both planets and you could try them both at 200x and see what happens. 

 

Also, you can get more magnificaion out of your 15mm eyepiece with your barlow installed, by pulling your eyepiece away from the barlow. Slide it out a little and your magnification will increase a bit more if you find 134 is awesome but 200x is too much.

 

If the Gods love you, and your area experiences 5/5 seeing conditions, you shouldn't have no problem getting 200x out of your 120mm reflector with excellent rock solid views. These are extremely rare nights so don't be surprised if this doesn't happen this year.  You should actually be able to push your magnification beyond 200x on 5/5 conditions but lets not push our luck. 

 

You mentioned you may consider a 12" dob.

If you get one, don't give up your 120mm reflector. I'm guessing its a dob also?

 

120mm is an excellent back yard size and easy to set up and use.

 

The 12" dob will absolutely give better planetary results then your 120mm reflector, but if you lack the seeing conditions for your 120mm reflector, you aren't going to get much more out of a 12" dob since you will still be trying to look through a larger hole of mediocre conditions with a 12" reflector. With bad seeing, sometimes more aperture is just more aperture and doesn't improve anything.  This is why you hear some people say their 4" refactors produced better planetary views them someone else's larger reflector. Its because of mediocre seeing conditions.

 

A 12" dobsonian opens up your entire sky to deep space observing. Even with your 120mm reflector. If the planets aren't so great, that doesn't mean you should pack in the scope. Use that aperture to hunt down the brighter Messier objects. There's a ton of them right between Jupiter and Saturn right now.

 

good luck!!!

 

...Ralph

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hi everyone. My name is Brian, I'm new here and new to astronomy, glad to be part of a forum for my new found hobby. I have a 120 x 1000mm reflector telescope my wife and I take out onto our back deck to look at the planets. I recently bought some middle-of-the-road Svbony wide angle eyepieces (10, 15, 20 & 23mm) to get away from the cheapy ones that come with the scope. We look at Jupiter and Saturn a lot, and they look cool, but they're small, especially Saturn. I start with the 20mm or 23mm to find the planets then work down to the 10mm to zoom in, but even with the 10mm the planets are rather small. We can see that Saturn has rings, but that's about it. I think I max out the scope with the 2x barlow and the 10mm. My question is, how do I get a larger view of the planets? Is it eyepieces? Mirror Diameter? Focal length? All of the above? I know 120mm isn't huge but it's a big step up from my 70mm travel refractor. I'm thinking about getting a used 12" Dob down the road, but I want to get the right one. Thanks everyone.


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#8 db2005

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Posted 18 August 2019 - 01:12 AM

You won't need a larger scope to see more than you describe. A 120 mm scope is already a powerful and very capable instrument.

 

To see more of Saturn than its rings you will need quality optics in good collimation, steady skies and patience. The Cassini division (a small gap in the outer part of its rings) is visible in 3" scopes but requires steady seeing. To see the subtle contrast differences on the planet's surface you also need patience and high-contrast optics. I've seen subtle contrast differences on the surface of saturn in a 80-100 mm scope. But the Cassini division frequently only becomes visible to me after I observe it for a few minutes... so don't expect to just take a quick glance at the planet and expect to see it right away.

 

If you use a 120mm/1000 mm reflector with 10 mm eyepiece and 2x Barlow lens magnification is already pretty high (200x) and unless the optics and seeing are great, I doubt it will show you more than 100x magnification. In my experience, reducing magnification can often increase the preceived contrast. If you have normal vision, you don't "need" a larger view of the planets to see more detail on them. A surprising amount of detail is visible already at 50x-100x. IME contrast is more important than magnification, and contrast can often be improved by reducing magnification a bit.

 

Of course, increasing aperture is an option, but I recommend you don't go down that route just yet, at least until you have used more of your current scope's potential. Larger scopes make every thing more complex: More complex transport, setup, more attention to collimation and thermal management/tube currents/acclimatization. And larger scopes need better seeing too, to perform to their full potential. In many cases a small scope will show better views than a small scope simply due to it being less affected by atmospheric disturbances than the larger scope. And larger scopes are typically faster (shorter focal ratio), meaning you need to buy more expensive eyepieces too.

 

Instead, I recommend you spend some time at the beginning of each observing session to check that your current scope is collimated. Also, wait until the scope is properly acclimatized before beginning to observe. 45-60 minutes is usually enough to reach ambient temperature, but your mileage may vary. Then, check collimation again by making a star test. When actually observing, have patience: keep observing objects for at least a few minutes before drawing any conclusions about the scope's capabilities.

 

One final word of advice if you do decide to get another telecope: If observing planets is your thing, take a look at telescope designs that are known for producing great visual contrast: Slow refractors or APOs, and MCTs, and slow Newtonian reflectors (with the smallest possible central obstruction).


Edited by db2005, 18 August 2019 - 01:15 AM.

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#9 Gary Z

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Posted 18 August 2019 - 01:29 AM

Don't let aperture fever ruin your love of the sky.  You may want to go large down the road, but there are downsides such as weight, cool down times (as db2005 as pointed out).  Someone asked us to look at their Meade Starnavigator NG with a 127mm Maksutov scope on it.  I tried out the mount and set it up, and while the goto wasn't perfect, that scope blew me away using nothing but the stock 26mm plossl eyepiece.  The views of the moon, Jupiter and Saturn blew me away.  Granted, I have a larger Celestron C8 and a few refractors, but the point is, this also is a great scope for planetary viewing.  In fact, I'm considering getting a Mak down the road and selling the C8.  

 

Also, I have a Stellarvue 80mm Doublet Refractor and last night, viewing Jupiter and Saturn with a 4.7mm ES eyepiece.  Dearly loved the views.  

 

Sure, no one is saying you need a larger scope, but learn what options will give you the best views for the particular aperture.  

 

Take care,

 

Gary


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#10 james7ca

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Posted 18 August 2019 - 01:37 AM

I'm going to suggest something that might seem a little radical. If you want a "larger" view of the planets then you should probably think about electronic, realtime imaging. Take a video camera like the QHY5III-178C or ZWO ASI178MC and attach that to your scope and then sit back and view the image (in realtime) on your notebook computer. When doing this you can get an image of almost any size by adding a barlow and/or by just zooming the display on your computer. Also, a video camera will allow you to change things like contrast, gamma, color, and exposure making some features even more visible.

 

This won't produce more resolution than you could get visually, but you might find that the image is much easier to view since you won't be limited by the small exit pupil that happens when using high magnifications on a relatively "small" telescope (meaning a very dim image). You also won't have to worry about "floaters" in your eye. The only real downside is that the video image will likely show noise at some gain and brightness settings. Also, at some limit you will become aware of the individual pixels that make up the image.

 

Of course, there is something to be said (in favor) about viewing an object directly with your eyes, so the video experience will be different but arguably superior by some measures. But, there is nothing that prevents you from using both methods.

 

Other than this, the only real solution to getting a "larger" image is a larger aperture telescope.



#11 sg6

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Posted 18 August 2019 - 02:01 AM

You need a scope capable of producing good quality high magnification images and the equally relevant eyepieces.

 

Since focal length and magnification are related the scope you have may be a little "short". and there is likely not a lot you can do. Then comes the quality. A good Zambuto of say 8" is likely to produce views you want but they cost.

 

I do not like the use of a barlow, they are an optical item and as such will be adding problems to the result. The question is how much of a problem. But most barlows are budget items.

 

Any chance of finding a club?

At least you will see a selection of scopes and maybe get an idea of the capabilities of each. Believe me things are not "simple".

 

You may find a 5mm or 6mm reaasonable eyepiece helps, I am half thinkingh an ES52 here as reports are usually good.

 

Saturn is relatively bright, so 120mm should be reasonable. But a reflector has that spider at the top and that contributes diffraction spikes which reduce the view. Not size however.

 

The classic "planet killer" is a long focal length refractor. Maybe there is something to be learnt from 100+ years of astronomy viewing. I say this as my best view of Saturn was through a s refractor of about 4" and 1000mm with an 8mm eyepiece, views through a 14" SCT have always been disappointing. So be a little wary of bigger, bigger, bigger.

Other than this, the only real solution to getting a "larger" image is a larger aperture telescope.

Since magnification is (scope focal length)/(eyepiece focal length) the scope aperture is not a factor in magnification.

You will get the same magnification from a 120/1000 scope and a 250/1000 scope with the same eyepiece. Should be brighter but not bigger.



#12 ButterFly

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Posted 18 August 2019 - 02:28 AM

A 5mm eyepiece should do you fine.

 

Saturn is going to be low in the sky for a few years, so timing is also important.  All views are better when they are higher in the sky becuase of less air the light travels through.  It is at it's highest in the sky aorund 10pm now.  Next month, at around 8pm.  By October, it's at its highest at sunset.  So your best time is that two hour or so window around that time - 9-11pm now, 7-9 next month, and so on.

 

Planets take practice and waiting for the air to calm down.  Keep at it.


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#13 db2005

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Posted 18 August 2019 - 02:42 AM

 I have a 120 x 1000mm reflector telescope my wife and I take out onto our back deck to look at the planets.

The choice of surface for setting up your telescope can have a huge impact on what you will be able to see. While planets aren't affected by light pollution and are excellent targets for suburban stargazing, they are affected heavily by air currents which wash out planetary contrast and detail.

 

If you set up your scope on a hard surface like a concrete surface or a tarmac driveway, vibrations will not be dampened, and the heat plume rising from such  surfaces can wash out planetary details. The same applies for nearby buildings: the heat plume rising from buildings significantly wash out views of targets above them.

 

In my experience, the ideal observing location is a green lawn at least several metres away from buildings: A green lawn does not generate a heat plume at night, and it's great for absorbing vibrations, ensuring steadier views.


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#14 Redbetter

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Posted 18 August 2019 - 02:46 AM

120mm should be sufficient for good views of planets with considerably more detail than what you are describing.  I would expect those eyepiece focal lengths to work well with a decent 2x Barlow assuming the scope is properly collimated and has acceptable optics.  What Barlow are you using?  Did it come with the scope (those can be pretty bad.)

 

Collimation and optical quality can be big factors.  What model scope is this?  The concern I have is that when I search for 120mm reflectors with 1000mm focal length I turn up some Jones-Bird types with short tubes.  Optically that type doesn't tend to perform very well.  I hope this is not the case for you and that you have a normal Newtonian reflector. 

 

If it is a normal Newtonian then you should be able to collimate it and do some other things to verify that it is configured properly and will be able to put up decent images.  Newtonians tend to require some adjustment so that they perform as expected.  There is a learning curve to it. 



#15 james7ca

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Posted 18 August 2019 - 02:49 AM

...Since magnification is (scope focal length)/(eyepiece focal length) the scope aperture is not a factor in magnification.

You will get the same magnification from a 120/1000 scope and a 250/1000 scope with the same eyepiece. Should be brighter but not bigger.

I don't think there was any dispute or question about how to determine magnification. But, APERTURE is what gives you resolving power and finer detail, focal length alone really has little to do with the LIMITS of what you can see through a telescope. I think most people understand the relationship between focal length and magnification, at least in terms of how that combines with the focal length of the eyepiece. However, in a practical sense aperture still matters (given proper setup and conditions).

 

You are correct, however, that at any given (high) magnification that the larger aperture would create a brighter image which is one reason why a larger aperture can produce a better viewing experience (which is, I think, what the OP is actually wanting to achieve). This also means that for equivalent brightness a larger aperture can use a higher magnification. But, as mentioned earlier by many people there are limits to useful magnification (because of the earth's atmosphere and its effects on the quality of the seeing). So, a larger aperture may not be able to use a magnification that will produce a larger image, but it may still provide a better view.

 

All this said, I agree with your statement that the situation is "not simple," because optics differ and seeing conditions can actually affect different apertures in different ways. Then there is the question of setup (temperature acclimation, the local environment, and things like collimation), simple user experience, and the condition of the observer (including visual problems -- astigmatism -- being one fairly common issue). And I might add that many visual problems can be overcome with the use of video observing of the planets and the moon (as I originally discussed).


Edited by james7ca, 18 August 2019 - 08:15 AM.


#16 jodemur

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Posted 18 August 2019 - 07:12 AM

I agree totally with this Philosophy. I haven' been at Astronomy all that long myself but realized some time ago that time at the EP and the occasional moment of fine atmospheric clarity can render much. I think, for our two brightest planets, that 133x to 200x give very satisfying views.

Many people don't like to hear this, but it takes practice (among other things) to really "see" planets (or any other astronomical objects) through a telescope.

 

If I understand your post correctly, your telescope has a 120mm aperture -- that's large enough to reveal quite a bit of detail on Jupiter and Saturn.  Furthermore, your telescope has a 1,000mm focal-length.  You can achieve the following (and more) magnifications, assuming you can use the 2x Barlow with any of the eyepieces you've mentioned:

 

23mm eyepiece -- 1000 divided by 23 provides a magnification of 43x

20mm --- 50x

15mm --- 67x

10mm --- 100x

15mm + Barlow -- 133x

10mm + Barlow --- 200x

 

That's a reasonable range of magnifications for a 120mm telescope.

 

While Jupiter and Saturn don't look particularly large at 100x, 133x or 200x, those magnifications are sufficient to reveal quit a bit of detail -- under good enough sky conditions (all nights are not equal in this regard) once the observer has gained enough experience.

 

Frankly, you don't really need to see larger views of the planets.  You need to take your time and look for finer details in the images that you do see.  Even then, it will take time (days, weeks, months, and yes, even years) to develop your observational skills through practice, practice, and more practice.

 

There's much to learn about using a telescope.  It's not just a simple matter of pointing a telescope and instantly seeing all there is to see of any targeted object.

 

If I manage to get around to it I'll take a photo (and post it here) of a painting I made in 2001 that shows the details that were seen on Jupiter and Saturn with a 80mm f/5 achromat refractor operating at a magnification of 105x.

 

On the other hand, if what you really want is just a larger view, you can get that by using a shorter focal-length eyepiece (such as a 6mm, 4mm, or 3mm) and/or a stronger Barlow (such as a 3x or 5x); but trust me, going that route will not reveal more planetary detail.  It'll make the planets look worse -- bigger, but dimmer and fuzzier.  A bigger image isn't always better.

 

Another solution is to go out and buy a larger telescope, but that too would be a mistake.  It's much better to learn how to "see" using a smaller telescope before jumping onto the larger telescope bandwagon.  Some things are just easier to learn while using smaller telescopes.  Besides, atmospheric conditions and other issues can make a large telescope (at times) no more effective than a smaller telescope.



#17 aeajr

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Posted 18 August 2019 - 07:27 AM

As has been said, assuming your 120 mm reflector is properly collimated, you have enough aperture. More is usually better but you have enough now.

 

It would help if we knew exactly what scope you have and exactly what eyepieces.  And how you are doing your collimation.

 

SVBony are not what I would consider mid grade eyepieces.   They are very much in the low end of eyepiece scale.  However, that relates to the quality of the image, not the size.  But you may be applying too much magnification for the atmospheric conditions. This will make the image large but degrade the quality of the image.

 

The atmosphere will be the primary limiting factor as to how much magnification you can apply to an image with a 120 mm telescope, or any telescope for that matter.  Today you have eyepieces and barlow to reach 200X.  That may be about the limit.

 

If you do get that 12" Dob you may be able to reach 300X on Saturn on a good night, but atmospheric conditions may limit you to 200X or less on many nights.  

 

At 100X in my 80 mm refractor I can see Saturn's rings quite distinctly and can sometimes pick up a cloud band on Saturn.  I don't think I can pick up the Cassini divide at 100X.

 

In an 8", 203 mm Dob I can pick up the rings, Casini divide and cloud bands on saturn, but typically am still limited to about 200X by the atmosphere.

 

In my 12" Dob I may be able to push to 250X and can see a bit more detail of the planet. I have a better chance of reaching 300X with this than the 8" but still, the atmosphere is the limiter. 

 

I also operate a 14" Meade SCT at an observatory.   The image is still going to be limited by the atmosphere. I had Saturn at 250X recently but could go no higher. 

 

The eyepieces I am using are promarily Explore Scientific 82 degree and a Baader Hyperion 8-24 zoom.   I would consider these upper midrange eyepieces.  


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#18 bfeeney

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Posted 18 August 2019 - 09:11 AM

You guys are awesome, thanks a million.

Ralph & Aeajr, I have the Galileo FS120DX scope I got used on FB for $45. The mount was missing parts and didn't have smooth movement so I put it on a Celestron Heavy-Duty Altazimuth Tripod. I would say to-date, the mount was the best improvement, tracking is almost fun now. I wish I could mount a 12" to one of those tripods.

I live in Columbus, Ohio, light pollution is bad. The good thing is that I live on the West side of the city and within a few miles further West I'm knee deep in corn country, less lights.

I bought a Astromania laser collimator and got the dot in the center, but it was pure luck, I don't know what I'm doing or why (the why part is just as important as the how part). This is where a telescope class would be nice, but I don't think there is any around here, not even a store that sells telescope. Youtube and forums are great, but I would like someone standing there showing me everything I need to know about these things. We have the Columbus Astronomical Society club, but it seems like that is a group of people who gather to discuss observing and to actually observe. I feel like I'd be a 4 year old being thrown into middle school rather than pre-school.

When I get better eyepieces, should I stick with wide angles or try some Plossl's? I've looked at a zoom eyepiece multiple times but I'm afraid it will fall into the 'Swiss Army knife effect' where nothing on there is great, only marginally ok just to check the box. I might be wrong.


Edited by bfeeney, 18 August 2019 - 01:08 PM.

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#19 phillip

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Posted 18 August 2019 - 09:13 AM

So much great info I will only relate to what's already said.

I also like the Explorer Scientific and Baader eyepieces as an excellent choice at reasonable

Cost but release nice images.

The sky conditions are the enemy as patience to observe those better than average and the very

Rare steady sky.

An amusing post here years back new amateur had a sizeable believe it was a 14" SCT. His First

Look at Mars was a red pulsating blob unresolved image. Actually said he was going to shoot his

New acquired scope because of the discussing image. Mars is a tricky one to catch it with details

Really need exceptional sky conditions.

I'll agree, use what you have, maybe a move up on eyepieces. Learn to patiently observe, even

The smaller image can release alot of detail, takes Practice!

Have fun, super hobby to learn and Enjoy!

Clear Sky!

ETX90, 4SE
XT8I, XT10 Dobs Reflectors

6mm baader still waiting for that steady sky!
4.8mm Nagler rarely use, but that rare steady sky barlowed a beauty on Mars
Don't count on it, reached this level can count on one hand, but be ready!

Edited by phillip, 18 August 2019 - 09:26 AM.


#20 vdog

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Posted 18 August 2019 - 09:15 AM

Bigger isn't necessarily better, especially with planets.  It happens that I was experimenting with higher magnifications (400-500x) last night than what I usually use on Jupiter and Saturn.  The seeing was pretty decent, but every time I do this I find that I'm not really seeing any more detail, just a larger image that I have to manually track more often.

 

I have to do this every once in a while to convince myself I'm better off with my usual magnifications. grin.gif

 

That said, a 12" dob would really open up the sky, not just planets.  I would say go for it, even if you have to wait awhile.  In the meantime, a better short focal length EP (ES 6.7, Meade 5.5) might help you out with planets.


Edited by vdog, 18 August 2019 - 09:16 AM.

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#21 ShaulaB

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Posted 18 August 2019 - 09:25 AM

Have you considered observing deep sky objects as well as planets? Your scope is capable of viewing many of them. It is small enough to be portable, so you can haul it to a darker site than your home. DSO's really pop under dark, Moonless skies.

You might want to start with the Messier list. It includes open star clusters, globular clusters, nebulae, and galaxies. Download the list, or find it in a book at your library. Sort through to find the objects with the brightest magnitudes. The lower the magnitude number, the brighter the object.

You will also need to learn star hopping. With practice, it becomes easier. Best of luck, and have fun!

#22 REC

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Posted 18 August 2019 - 11:38 AM

Hi everyone. My name is Brian, I'm new here and new to astronomy, glad to be part of a forum for my new found hobby. I have a 120 x 1000mm reflector telescope my wife and I take out onto our back deck to look at the planets. I recently bought some middle-of-the-road Svbony wide angle eyepieces (10, 15, 20 & 23mm) to get away from the cheapy ones that come with the scope. We look at Jupiter and Saturn a lot, and they look cool, but they're small, especially Saturn. I start with the 20mm or 23mm to find the planets then work down to the 10mm to zoom in, but even with the 10mm the planets are rather small. We can see that Saturn has rings, but that's about it. I think I max out the scope with the 2x barlow and the 10mm. My question is, how do I get a larger view of the planets? Is it eyepieces? Mirror Diameter? Focal length? All of the above? I know 120mm isn't huge but it's a big step up from my 70mm travel refractor. I'm thinking about getting a used 12" Dob down the road, but I want to get the right one. Thanks everyone.

I run my C102 f/1000 up to 150x using a ES 6.7mm eyepiece and the planets give a good view. You need to learn about seeing conditions. If they are good, 150x will give you pretty clear views of them. Go to www.cleardarkskys.com. You want to have a night where the ratings are at least 3/5, but better at 4/5. I never get 5/5 where I live.



#23 aeajr

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Posted 18 August 2019 - 12:48 PM

You guys are awesome, thanks a million.

Ralph & Aeajr, I have the Galileo FS120DX scope I got used of FB for $45. The mount was missing parts and didn't have smooth movement so I put it on a Celestron Heavy-Duty Altazimuth Tripod. I would say to-date, the mount was the best improvement, tracking is almost fun now. I wish I could mount a 12" to one of those tripods.

I live in Columbus, Ohio, light pollution is bad. The good thing is that I live on the West side of the city and within a few miles further West I'm knee deep in corn country, less lights.

I bought a Astromania laser collimator and got the dot in the center, but it was pure luck, I don't know what I'm doing or why (the why part is just as important as the how part). This is where a telescope class would be nice, but I don't think there is any around here, not even a store that sells telescope. Youtube and forums are great, but I would like someone standing there showing me everything I need to know about these things. We have the Columbus Astronomical Society club, but it seems like that is a group of people who gather to discuss observing and to actually observe. I feel like I'd be a 4 year old being thrown into middle school rather than pre-school.

When I get better eyepieces, should I stick with wide angles or try some Plossl's? I've looked at a zoom eyepiece multiple times but I'm afraid it will fall into the 'Swiss Army knife effect' where nothing on there is great, only marginally ok just to check the box. I might be wrong.

Understanding Telescope Eyepieces- There are recommendations, based on budget, but the meat of the article is about understanding the issues when selecting eyepieces.
https://telescopicwa...cope-eyepieces/

 

The article says it all. 

 

Plossls are good, inexpensive eyepieces.   However the trend is to wider.  How wide?   How much money do you have and how large is the focuser on your telescope.   I presume it takes 1.25" eyepieces.

 

Zoom eyepieces are my most used eyepieces.

 

For my Single FL 1.25” eyepieces  I have the Meade and ES 82s.   Like them very much

 

AT Paradigm line 60 degree AFOV. - very good lost cost eyepieces.

https://www.astronom...pieces_c52.aspx

 

Meade 82 degree - I have a pair of these and like them. 
https://www.astronom...pieces_c75.aspx

 

Explore Scientific 68 degree and 82 degree line.  I have fpur of the 82 degree and really like them.  Many reports compare these favorably with the premium eyepieces.
https://agenaastro.c...scientific.html

 

Meade 82 vs. ES 82 - Discussion

https://www.cloudyni...e-82-eyepieces/

 

 

AT Paradigm line 60 degree AFOV.  

The Agena Astro Dual ED are the same eyepieces under a different label.

https://agenaastro.c...sult/?q=dual Ed

Discussion about Paradigm eyepieces
https://www.cloudyni...s/#entry8229760
https://www.cloudyni...s/?hl=+paradigm

 

 

Celestron Zoom eyepiece review - I have this one

https://telescopicwa...yepiece-review/

Zoom eyepiece review – Includes the Celestron zoom –
This is an older review and the tech specs may not match the current Celestron zoom, but I find the comments nicely reflect the performance of the Celestron zoom I own –

http://www.chuckhawk...m_eyepieces.htm

 

 

Baader Hyperion Mark IV Zoom review   - The current model  - I have the older model of this one - my primary eyepiece.

https://astronomycon...ox-january-2018



#24 Redbetter

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Posted 18 August 2019 - 02:02 PM

You guys are awesome, thanks a million.

Ralph & Aeajr, I have the Galileo FS120DX scope I got used of FB for $45. The mount was missing parts and didn't have smooth movement so I put it on a Celestron Heavy-Duty Altazimuth Tripod. I would say to-date, the mount was the best improvement, tracking is almost fun now. I wish I could mount a 12" to one of those tripods.

I live in Columbus, Ohio, light pollution is bad. The good thing is that I live on the West side of the city and within a few miles further West I'm knee deep in corn country, less lights.

I bought a Astromania laser collimator and got the dot in the center, but it was pure luck, I don't know what I'm doing or why (the why part is just as important as the how part). This is where a telescope class would be nice, but I don't think there is any around here, not even a store that sells telescope. Youtube and forums are great, but I would like someone standing there showing me everything I need to know about these things. We have the Columbus Astronomical Society club, but it seems like that is a group of people who gather to discuss observing and to actually observe. I feel like I'd be a 4 year old being thrown into middle school rather than pre-school.

When I get better eyepieces, should I stick with wide angles or try some Plossl's? I've looked at a zoom eyepiece multiple times but I'm afraid it will fall into the 'Swiss Army knife effect' where nothing on there is great, only marginally ok just to check the box. I might be wrong.

 

Ok, it is a real Newtonian, 120/1000.  Perhaps some others here will have had experience with that particular model and be able to provide specific suggestions about collimating it or about the best way to configure it.  It isn't a Jones-Bird (and those are usually 114's anyway...but for some reason Levenhuk was listing a 114mm short tube Jones-Bird scope as a 120x1000 at the top of the searches I did initially.)

 

As you have discovered, most very inexpensive beginner scopes that are on tripod mounts are woefully under mounted and nearly unusable until that is addressed.  You have already gotten a workable solution for that, so now it is a matter of improving the quality of the image.

 

My guess is that your primary problem is collimation.  When you say you have the dot aligned, the question that arises is whether you have aligned both mirrors or just one?   In the first step with the laser, the secondary mirror is aligned with the primary by using the adjustment screws (whatever type they are) to get the laser dot to land in the middle of the primary mirror.  This assumes some sort of visible mark is in the center of the primary (and that it is actually properly placed in the center.)  The second and most critical part is aligning the primary by centering the return beam in the target window of the collimator.  This is done by adjusting the collimation knobs on the primary mirror. 

 

The caveat to this is that before initially using the laser collimator, the collimation of the laser itself should be checked to be certain it is not skewed.  If it is off, then one will be introducing collimation error.  One might need to adjust the collimator first.  A way to partially work around this even if the collimator is a little off is to use the Barlow laser collimation method, which is a little more complicated but will make the key part of collimation accurate (the second step, aligning the primary).  The Barlowed laser method doesn't fix the error of aligning the secondary, which doesn't use the Barlow for alignment, but that is the less important error. 

 

And some use simpler collimation caps and such for visual collimation.  These work best with some daylight, which I rarely have when setting up.

 

Once you have it collimated, and after it has had ample time to thermally equilibrate with the ambient outdoor temp, you can do a star test at high power on a star.  With a bright star centered, going back and forth through focus slowly should reveal an airy disk pattern at focus (1st and possibly 2nd diffraction ring), then a growing number of rings spreading out as one moves further from focus.  The pattern should be round, not oval/elliptical, not triangular, comet shaped, or otherwise misshapen.  The central disk at focus should be round.  It shouldn't be a cross, or cigar, or some sort of triangle. 

 

If you see any of these sort of major defects they will considerably reduce the quality of the image for planets and such.  Some of them can be the result of correctable mechanical problems with the way the optics are supported and kept in place, some are miscollimation issues, but others can be due to problems with the mirrors themselves. 

 

Assuming one doesn't see any major defects, there still could be some considerable spherical aberration (over or undercorrection of the primary mirror.)  This should appear as considerably different brightness patterns to the rings at the same distance on either side of focus and can be a very sensitive test, so it is hard to tell what is acceptable.  At the eyepiece large amounts of spherical aberration tend to be seen as a planet or star image that never achieves a good focus at high power (which is also true of other defects to some degree...although they have characteristic patterns that allow one to distinguish them.)  With damaging levels of spherical aberration the scope sort of mushes through focus over a long range--teasing but never getting crisp.  It lacks what we call "snap to focus." 



#25 Zorbathegeek

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Posted 18 August 2019 - 05:06 PM

Lots of very useful advice on here re the adequate nature of your scope. I can't imagine I'll ever be able to afford an 18" Newt'. I love my 6" Dob'. It's had constant use over the past 12 months and I thought (12 months ago) that I'd be ready to upgrade by now, but the night sky is as limitless as your imagination. As a newbie, it's taken me months to realise that I can see amazing things with averted vision and letting my pupils dilate properly. I think if I upgraded now it would be like starting the 2nd course before I've finished chewing the first course. Spotting asteroids is one of my favourite exercises. They're only points of light in the scope, but knowing what they are and reading a bit about each one before it reaches opposition just fuels the imagination, and star hopping for 10th magnitude objects, whilst it can be a bit of a brain-melter, offers an incredible sense of achievement. As to Jupiter and Saturn, I have to wait until the seeing is excellent before I can use my barlow. However, the fact that that doesn't happen very often makes is so much sweeter when it does. In an article in August's Sky & Telescope about embracing the constraints of a small scope, the author quoted Ernest Rutherford who was working from a "ramshackle lab with a limited budget." Since the competition was so much better endowed, Rutherford said to his colleagues, "We haven't got the money, so we'll have to think."  


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