I've eyed a starter scope - but any good?

[Dr Nurburg]

Thank you all for your time, I am outstanded at your good will to help me in such detail.

Obviously I want to make sure I am not buying something I will regret.

From what you've told me, I have now come to assume that the best image of Jupiter I will get, using the Dobsonian 150P, and I expect only with a 5mm eye piece, would be like the one I have attached to this post.

Do you think I have made a correct evaluation or, what would you say is the maximum quality/result I would get?

Many thanks...

[pvaz]

Thank you all for your time, I am outstanded at your good will to help me in such detail.

Obviously I want to make sure I am not buying something I will regret.

From what you've told me, I have now come to assume that the best image of Jupiter I will get, using the Dobsonian 150P, and I expect only with a 5mm eye piece, would be like the one I have attached to this post.

Do you think I have made a correct evaluation or, what would you say is the maximum quality/result I would get?

Many thanks...

Yeah thats about it. You can use this site to have a simulation of Andromeda and M13. change the EP to 10, 5mm or whatever you want to test on the form then press view.

I do see color clearly on planets (jupiter, mars and saturn). Publicity often makes people think they can see color on DSOs. Some show signs of green and blue but not many do. The eye rarely sees color at low light levels. It's like looking at lots of cars in a parking lot at night without much light. You can see shape but its hard to tell the colors.

I'm glad to help. Other people here toke the time to explain me stuff when I started (and they still do now). I would not know what I do know now if it wasn't for them so I like to help whenever I can.

[Dr Nurburg]

Ace that sounds like what I should expect for under £200.

How do you work out the aperture though? The product page doesn't seem to tell you what that is.

Cheers again, we're getting somewhere now.

[pvaz]

Ace that sounds like what I should expect for under £200.

How do you work out the aperture though? The product page doesn't seem to tell you what that is.

Cheers again, we're getting somewhere now.

It's the diameter of the primary mirror for the dob and the diameter of the lens for the refactor.

The dob is 150mm (about 6") and the refractor is 70mm (a bit less then 3").

[Capricorn]

Jupiter is a big planet, unfortunately it is a long way away. So it is SMALL!

If you bought a 12inch SCT (£1200) you would probably just see 2 bands. I looked at Jupiter through a 70mm refractor and later through a 14 inch SCT. At both times I saw 2 bands, and 4 little dots that were the moons. Amazed at how similar the view was.

I read a lot of instances of people having had 80mm refractors and they seem to be good as a general purpose scope. However decent ones still cost money.

No idea where you are in the UK but a visit to an astro club may help you get some idea on the capability of the various types and sizes. If you are down around the Guildford area then there is a public evening there Friday or Saturday, lots of scopes expected. Advertised here under IYA2009 I think.

[Capricorn]

Where did the image of Jupiter come from?

I ask as it is about the right size for say 100-120x but it looks very sharp.

If it is an picture that someone has imaged then it is not exactly the same as you will see.

A common imaging technique is to "stack" images. This is a case of taking say 80 images, determining the best 20 say, then stacking these one on top of another. So the quality is built up and then it can be sharpened. You eyes don't do this.

[Astro_Baby]

If you want a rough idea of what Jupier looks like take a look at this review of the Sky-Watcher 130 (thats a 5" reflector) like the 150 Dob thats being talked about but a teensy bit smaller.

Review of the Sky-Watcher 130PM

Look about halfway down the page and I have done some sketches to give you an idea. These were not done at very high magnification.

High magnification is not always possible with the UK atmosphere where your limited under normal conditions to about x200 and frequently less than that in my experience.

I have never seen more than two distinct bands on Jupiter even with my 8" but then I seldom spend much time on planets. I have yet to even see the red spot (which is actually a sort of grey color these days I am told).

[Dr Nurburg]

If you want a rough idea of what Jupier looks like take a look at this review of the Sky-Watcher 130 (thats a 5" reflector) like the 150 Dob thats being talked about but a teensy bit smaller.

Review of the Sky-Watcher 130PM

That looks very pleasing. What size eye piece were you using for that? Makes the 150P sound very attractive.

[Chris H]

As a rule newtonians are better for deep space objects (DSOs) and refractors are better for planets producing a sharper image at higher magnification. A good refractor on a decent mount is going to cost you a lot more than your budget allows. See this link for example

Skywatcher Pro Astronomical telescopes

and that price does not include a mount or better eyepieces. Also you can only see seven planets and four of those won't show any detail and will just appear as a small pale disk. It is a much better idea to go for something like a 6 or 8 inch newtonian reflector on a dobsonian mount £175 - £265 these scopes come with two eyepieces 25mm and 10mm which is fine to get you started and offer the ability to see many things in the night sky for example planets, nebulae and star clusters. You will have to get to grips with collimation but it is not as hard as it seems and you improve with practice. In my opion this is certainly the way to start with a telescope you can expand your equipment with better eyepieces and by adding filters to get better views of DSOs.

Where in the world are you? This is important because the sky conditions determine what magnification you can use, if its in the UK then it is rare that you can get near to or over x200. Most of the time it will be a lot less. I spend much of my time scanning for DSOs at x40 which may not seem much but it provides some great views and a wide field of view.

If you go down this route it should'nt break the bank and if you don't like it you can sell everything and not make too much of a loss.

[Astro_Baby]

To the best of my recall the EP in use would have been around 10mm - certainly not smaller than 6mm because with that scope I only ever used the Celestron Eyeopener kit and the smallest EP in that I just couldnt get on with.

I generally dislike much below about 7mm because I find them hardwork so my bet would be I was most likley using the 9mm.

If I may offer some small advice - dont get hung up on magnification. All beginners want to have a go at getting planets the size of a dinner plate in the eyepiece. The reality is without a massive telescope and perfect skies it wont happen. On a small scope you will find that as you push the magnification the view gets worse and worse and harder to control. At powerful magnifications planets move across your field of view in seconds, the atmosphere wobbles alarmingly, focus becomes more and more critical and with each touch of the focuser you will introduce yet more wobble into the view and eventually even a sparrow breaking wind 400 yards away will cause heat haze - well maybe not the sparrow but it will seem like it

Most beginners as I say want to go for massive magnification - most end up realising that low magnification provides a better experience. I almost never go much below 13mm on my 8" and thats with a mount that tracks for me. Partly thats down to weather and atmosphere and partly because I find the view hard work.

Anyway - hope thats some useful input for you.

[oceanheadted]

Mel,

(like the new avatar!) Interesting comments on eyepieces, I was beginning to wonder if I was missing something by avoiding the short focal length eyepies, I rarely seem to get any advantage in going much below 10 mm on my refractors which have a slightly shorter focal length than your 200p.

cheers

Alan

[Dr Nurburg]

So is the Dobsonian 150P electric then? Or does it have a battery? I am surprised it needs power because I didn't think they needed power until they were extremely powerful. But I've read posts that suggest it needs to cool down as if it's being powered.

Can someone enlighten me here?

Many thanks.

[Chris H]

No it is not electric or powered. By cool down all that is meant is that before you use it on a cool or cold Autumn or Winters night it must be left outside to 'cool down' and reach thermal equilibrium with the environment. An un-cooled mirror can degrade image quality. Some reflectors have a fan fitted to the base to speed up the cool down time. You don't really need a fan on a scope with a 6 inch mirror, cool down time will be normally less than one hour. Hope this helps.

[crepitis]

when the telescope is stored during daytime, with the cap on the end of the tube, the column of air inside will be at the ambient temperature, when the telescope is taken outside and the cap removed the warmer air inside the tube will have to escape into the cooler outside atmosphere, otherwise its like looking through a heat haze on a warm day, and any image you view will be adversely affected,

Cooldown time depends on where the scope is stored, if its indoors in a warm room then it will take longer than if it was stored outside in a shed or garage and much closer to the outside temperature.

As for the image of Jupiter you will see,, I had a look through my Tal 100RS Refractor last night ( a 4" refractor on an equatorial mount), and even allowing for the fact that Jupiter was pretty low in the sky, with a televue 20mm plossl and a Meade 14mm Ultra Wide Angle 2" eyepiece 2 bands on Jupiter were clearly visible, along with 4 moons, so I would expect a 6" aperture scope like the skywatcher dob to give similiar, if not better, views.

[topdude]

How about one of these

Sky Watcher Sky-Watcher Deluxe 80mm Astronomy telescope starter kit

Skywatcher is a good make, nice and portable, has an erecting diagonal, easy to use, good price