[Mr Jepps Se]

Hi ya.

I don't want to spend more than £100 and I don't want to have to spend hours setting the darn thing up. So I've spotted one within my price range and was wondering if I could get an evaluation from you guys.

The one I'm looking at is:

Celestron AstroMaster 70 EQ

It's specifications are:

OPTICAL DESIGN Refractor
APERTURE 70 mm (2.76 in)
FOCAL LENGTH 900 mm (35.43 in)
FOCAL RATIO 12.86
EYEPIECE 1 20 mm (0.79 in)
MAGNIFICATION 1 45 x
EYEPIECE 2 10 mm (0.39 in)
MAGNIFICATION 2 90 x
MOUNT CG-2 Equatorial
OPTICAL COATINGS Fully Coated
WEIGHT 18 lb (8.16 kg)

My questions are:

1. Any good as a starter scope?
2. How clearly could I see say the bands of Jupiter, or the rings of Saturn?

I don't want to buy anything really unless I can actually see the patterns in the atmosphere of planets. I would certainly like a good close up of the moon, space station and preferably Mars.

Any advice would be more than welcomed!

[Doc]

My neice has one of these and my thoughts are....

I'm going to be blunt here and say that you will be disappointed with this scope, for starters it's small aperture will not let you see that much detail on planets, deep space objects will be very hard to find unless observing from dark skies. The moon should look nice, but I do honestly think you will out grow it very quickly.

Ontop of this this the EQ mount is very wobbly and this causes alot of wobble at the eyepiece.

The problem you hace is £100 is not alot of money so I advice to buy second hand and try and get a bargain.

[jgs001]

If you can stretch the budget a little, then I hear this is a good option

Dobsonians - Skywatcher Heritage 130p Flextube

The mount is very simple to use.

[Mr Jepps Se]

Ah shoot... I should have known the universe would be more expensive than that! But heh, it is nearly 2010, can't blame me for trying. lol.

I'll raise my budget a bit. I'll have another look for maybe the £200 mark, but if you can actually recommend one meanwhile, that would be much appreciated.

Simon

[Mr Jepps Se]

Originally Posted by jgs001

If you can stretch the budget a little, then I hear this is a good option

Dobsonians - Skywatcher Heritage 130p Flextube

The mount is very simple to use.

That looks very nice, but seems I'd need to carry a table top about with me... I'd prefer one with a tripod to be honest. But I'll keep that in mind if all else fails.

[Doc]

This is a bargain.....

Dobsonians - Skywatcher Skyliner 150P Dobsonian

[jgs001]

In that case what about

Dobsonians - Skywatcher Skyliner 150P Dobsonian

[Doc]

In your post you say you want one easy to set up.

Well you cannot get easier then a Dob. A cheap EQ mount is a pain in the bum to set up and use.

[Doc]

Originally Posted by jgs001

In that case what about

Dobsonians - Skywatcher Skyliner 150P Dobsonian

LOL snap john, exactly the same time.

[jgs001]

ain't that just so...

You don't need a tabletop though, just a floor. Take out, put on the floor and away you go. You don't have to polar align, work out the odd way that the scopes move to align on your target etc.. The movements make sense (Up, Down, Left and Right...)

[Mr Jepps Se]

Originally Posted by jgs001

In that case what about

Dobsonians - Skywatcher Skyliner 150P Dobsonian

Seems like a good choice then. Hell I'm used to rolling around on the ground with my binos, I'm sure I can follow suit with a scope.

[ash]

As i have purchased the 200 version of said scope and i can vouch for the ease and simplicity of setting up and using.

Plonk it on the floor let it cool for 30mins...and the universe is your oyster.

And the views are stunning...simples

Andy

[pvaz]

Originally Posted by Mr Jepps Se

Seems like a good choice then. Hell I'm used to rolling around on the ground with my binos, I'm sure I can follow suit with a scope.

I have a similar one, same hight but a bit wider. Great to use and no setup time. I take an old office chair, with wheels, outside and it's very comfortable to use the scope.

[Mr Jepps Se]

One thing I heard is that some scopes relay the image to you upside down and in some cases at an angle.

Will this (Dobsonians - Skywatcher Skyliner 150P Dobsonian) be the right way up, ie as I would look at it with the naked eye?

[jgs001]

I'm not sure which scopes do what with the image (I can never remember), but any mirror changes the orientation of the image. For Deep Sky this really isn't an issue. It can be confusing at first on the moon when comparing to a normal view map mind you. That's also why I swapped out my normal finder scope for a red dot finder. I couldn't get to grips with the inverted view through the finder.

[wulfrunian]

The Dobsonian will give you a completely inverted image - upside down and left to right - image compared with what you see with the naked eye.

[Mr Jepps Se]

In which case, any suggestions for a scope under £200 that doesn't invert the image and which is strong enough to see the colored patterns in Jupiter's atmosphere?

Many thanks.

[JamesK]

You'll be hard pushed to find a non-inverting astronomical telescope. It doesn't really matter in Astronomy which way you're looking at the thing, it's orientation will change as the time of night and the year progresses anyway.

[Mr Jepps Se]

Ah ok. Thanks.

[pvaz]

Originally Posted by Mr Jepps Se

In which case, any suggestions for a scope under £200 that doesn't invert the image and which is strong enough to see the colored patterns in Jupiter's atmosphere?

Many thanks.

Most telescopes in astronomy invert the image. Either upside down only or upside down + left to right.

Only exception is a refractor with a prism (corrects the upside down), but then you get problems caused by refracting light such as color aberration. To avoid this you need an APO. If you want a small APO refractor you'll be looking in the range of 500£ and you'll have about 25% of the light gathering capability of the suggested scope.

Dobsodians are Newtonian scopes on a dobson mount. A Newtonian scope uses 2 mirror to relay the image to the Eyepiece, this causes the image to be inverted twice, upsidown and left to right. Mirrors don't cause cromatic aberration and are cheaper to produce then lenses. Even the hubble is a newtonian. For astronomy it will do great. If you want it for terrestrial use then you need a refractor.

[Mr Jepps Se]

Originally Posted by jgs001

In that case what about

Dobsonians - Skywatcher Skyliner 150P Dobsonian

As I said I am new to astronomy apparatus, I have just got to grips with specifics in Binoculars. I understand the magnification on my binos to be 15x.

The Dobsonion has different types of magnification figures so I am a bit confused as to its strength.

Does "Highest Practical Power (Potential): x306" mean it will magnify to 306x, or is this just some "relative" jargon?

Simon

[jgs001]

Simon, magnification is a factor of the eyepiece used. Divide the focal length of the scope, by the focal length of the eyepiece. The scope is 1200mm long so using a 20mm ep will get you 60x. As a guide, roughly twice the aperture in mm is the maximum useable magnification. Even then, there are times when that's just too much power for the atmospheric conditions and your view deteriorates into much. However, magnification is only part of what a scope can be used for. Unless you're looking at the moon or planets, high magnification will not show you very much as the objects will be too large, and tracking gets much harder.

What a scope is very good at, is gathering light. Now, your eye, has an aperture of about 5mm... The 15x70's are 70 mm, but that describes the diameter, and light gather is about surface area. 150mm, that scope, is much much better than the binos, which are much much better than your eyes for gathering light. This enables you to see faint fuzzy objects more easily.

I hope that makes sense and helps...

[Mr Jepps Se]

Taking your tuition in hand, I am not convinced that this Dobsonian will give me images of the colored patterns in Jupiter's atmosphere. Or if it does only 1 or 2 bands. Unless, are there 5mm eye pieces that I could use and would that make it more powerful?

I follow your bit about dividing the focal lengths, but I cannot see why you recommended this one, as 120x with the 10mm eyepiece supplied won't give me much deep space entertainment.

Or am I overlooking something?

Thanks again you are kind to give advice.

[jgs001]

I think it would be fine. I've seen the two main planetary bands on Jupiter with my st80 at 160x with a 5mm ep and a 2x barlow. I'm not sure about colours though... I don't know if the eye is sensitive enough unless it's a very big scope

[pvaz]

Well I have one and most deep space objects (DSOs) such as galaxys, clusters and nebulas are wider then you would expect. For most of them I have to use the 32mm EP (37,5x on my scope) I bought and some won't even fit completely in the field of view (FOV). For DSOs the most important thing is aperture since most of them are wide but dim. There are exceptions, such as the Ring nebula (M57) or the hercules globular cluster (M13) witch I like to observe with either the 15mm or the 10mm EP. Upping the mag increases size but reduces brightness. On dim objects its preferable to see them small but with the best contrast and definition possible, then to see them big and dimmer.

Planets appear much smaller but much brighter. So for planets a telescope with a small aperture (less light gathering capability) will do. On planets you will want high mags, so a 5mm is a good buy. On the other hand, you'll learn through experience, that as you up the mag you also magnify the seeing conditions caused by the earth atmosphere. This causes things to look bigger but less sharp, unless you have a perfect clear night. Thats why the hubble with a 2m aperture (i think) takes better images then telescopes on earth with 10m aperture but influenced by atmosfere.

I'll run a comparison between the dob and the 1st scope you sow so you can better understand the differences in design.

Aperture: The dob provides a bigger aperture. Light gathering depends on the area, so its pi times radius squared. If you run the math the dob haves almost 4 times the area so 4 times more light gathered from dim objects. Much more DSOs will be available with the dob.

Max Magnification: No info on the refractor page, but normal rule is 50x per inch, so around 150x potential max for the refractor. 300x max for the dob. So the dob will give you more freedom on planets. With the provided EPs the dob gives 120x max and the fractor gives 90x max.

Image: The refractor presents a corrected image, so you can use it on earth. Since refracting separates the colors (chromatic aberration, CA) you may see a purple hallo around bright objects such as the moon. Some people can't stand CA, some don't care. The dob doesn't have CA but inverts the image.

Mount: The dob uses a short, cheap but very steady mount. So it wont shake as much with wind gusts and so. The mount on the dob requires no setup but you track objects with less ease when they appear to move due to earths rotation. The refractor haves an eq mount. It haves a setup time to align with the north star (polaris), witch effectivly aligns it with the earth axis, then it's easier to track objects.

I think I just beat my record for the longest post!

That's what you get on a slow day at work...