another start up question.....

[chloe2005]

if they are both nexstar scopes...why do they look so different?

[Schorhr]

Hello,

no, 114 or 76 is the aperture in this case, the lens or mirror diameter.

As the surface area is what counts, a 114mm mirror will in theory gather 2.2x as much light as a 76mm mirror, so already more then double.

The resolution does not quadruple but increase too, of course.

BUT: There are other aspects.

Size of the secondary mirror (obstruction) that blocks some light and decreases the contrast.

This is why a mirror telescope will be a bit worse then a lens telescope with the same aperture.

BUT: A simple refractor, especially the short ones, will have visible color fringe at higher magnification, while short newtonians (under f/5 aperture ratio) will suffer from Coma.

But wait, it gets even more complicated. The Celestron N 114/1000 is a short tube, actually a 114/500 with an aditional lens in the build to reach 1000mm focal length. This has multiple disadvantages (difficult collimation/adjusting, chromatic abberation, most of these telescope types don't even have a parabolic mirror), but makes the tube lighter (so a cheaper mount can be used).

Also those ebay offers will probably end up with a higher price.

For planets, GoTo is NOT neccesary. Jupiter and Saturn are so bright, they can be seen with the naked eye and are often mistaken for the north star for example (when they are high up in the sky).

All you need to do to find a planet with your telescope is to check it's current position (in Stellarium for example), go outside, and point at the brightest "star" in that direction.

I'll try to sum it up;

-Aperture is the most important thing, especially for deepsky observing

-Twice the aperture in mm is the max. useful magnification

-The focal length devided by the eyepiece focal-length will equal magnification

-Newtonians with a tube that's much shorter then their focal length are Catadioptric systems. If the focuser/eyepiece is at the side, it's one of those with a built in lens and should be avoided by beginners. Other Designs such as Maksutov, where the focuser at the rear, are a different type and actually pretty good for planets

-Short refractor type telescopes suffer from chromatic abberation, and are not well suited for planetary use (for example the 70/400 and other starter telescopes like this )

I would not recomend anything under a 102/1300mm Maksutov, a 114/900 Newtonian or a 80-90mm refractor if planets are the main target.

The problem is usualy not the telescope, but the mount. This is why dobsonians are so popular.

The 130/650mm Heritage is so popular as it's very stable, portable and offers a large aperture for the price. The short focal length is often criticized but it actually holds collimation well and does a good job for planets as well, if you buy another eyepiece.

The problem with the other 130/650 and 114/900 newtonians is that they are often bundled with a EQ-1, EQ-2 or fake EQ-3 (Astro3 instead of a real EQ-3-2) mount. Over 100x the view does shake a lot and makes observing planets difficult.

GoTo is a nice-to-have, but if you can align the computer at two bright stars, you can find the planets just as well manually. And from within a town the GoTo won't help you see faint objects, plus it does tempt one to hop from one object to another- without learning the skies and taking time to observe. My best observations where done while looking at the same objects over half an hour, out on a dark field... And that's where a manual, light telescope without the need of batteries does come in handy.

[chloe2005]

W O W

my head is buzzing with all the variations available........

I agree a goto is a lazy option, but my thought process is as she is a beginner and has some learning difficulties (also short term memory is poor) if i can get something that allows her to see what she wants to see more readily and possibly independantly then that will grow her thirst for more and as she leanrns slowly along the way, the manual knowledge may stick

[Cornelius Varley]

if they are both nexstar scopes...why do they look so different?

The Nexstar bit is the mount. The 102 is a refracting telescope and the 114 is a reflector .

[Schorhr]

Sorry, I know it's a lot of info, but as you say, a lot of variants available, and difficult for a beginner to make sure to buy something good (an not some weak mounted, difficult to adjust rip-off kit).

Let me put it this way...

Price:

-130mm Telescope: 120-130£

-130mm GoTo Telescope: 285£

-70mm GoTo Telescope: 200-220£

So the GOTO Mount costs about as much as the telescope itself, the manual telescope will show the same thing though.

Set-Up:

Dobsonain->

Take outside, put eyepiece in, look through finder scope, point at brightest dot in the sky, observe.

(Tracking is done smoothly even at 200x, and wide-angle-eyepieces with higher power start at 27gbp.)

GoTo-Telescope->

Take outside, assemble with tripod, check batteries, enter coordinates, put eyepiece in, align with two stars that must be visible from your current location coordinates, acknowledge, observe, possibly correct positioning on higher magnification manually.

Of course goto can be learned and is easy once you 've done it, but don't take it as the easiest solution, especially if your daughter suffers from memory issues :-(

It's actually faster to set up a dobsonian, especially if you want to look at the moon and planets.

I have read a nice post on here why someone went from goto to dobsonian, but I was unable to find the post now.

All I am saying is that you should not buy a tiny, weak mounted telescope just to get GoTo. Again, it would be best to visit an observatory and possibly try a few telescopes if possible.

At the end it's your decision, just consider all the options and don't believe all the advertising ;-)

If you can spend 200£ or more, though, it is an option to consider. On the other hand, this may buy you a used 8"...

[chloe2005]

Thanks all

I think i'm going to lean on a Dob (check me out with the lingo already).........

As long as it easy to set up and Chloe can use it on her own as she wants to then i'm happy with that

If she can look through and see the rings of Saturn or the Red eye (is that within budget of a starter scope) then she will be more than happy

the moon is naturally also of interest - but as its so close isnt really an issue regarding a scope purchase.....or is it???

[LTB]

The only concern I have is with the "wow" factor. 

I have a friend who bought an inexpensive tripod and some decent used binoculars and he and his son have a blast for about an hour 3-4 nights a week.   His son has some learning disabilities as well.  His dad uses an I-pad with Sky Safari on it and brings up the constellation photos and then they look and trace the constellation and he tells his son the story of how that constellation got its name and then delves into some lore and history of the name.  They have a good time and learn a lot of history and a little bit of science. 

For them the "wow" is in the learning and not so much in the seeing.....Good luck.

[chloe2005]

any good?

http://www.ebay.co.uk/itm/IDEAL-FOR-XMAS-TELESCOPE-ORION-DOBSONIAN-SKYQUEST-TX4-5-INC-MOON-FILTER-PACK-/200970904147?pt=UK_Photography_Telescopes&hash=item2ecacca253

[Schorhr]

I think i'm going to lean on a Dob (check me out with the lingo already).........

Hehe, starting to get a pro! ;-)

The "red eye" is getting a bit weak, actually, and it depends on the conditions, light pollution, air transparency, seeing, how for Jupiter is up in the sky...

At 200x magnification both Jupiter and Saturn will be "pea sized", and more then 200x is not allways possible due to the turbulant air layers.

Jupiter will almost always show two cloud bands and it moons are quite fast, even an our later they will stand slightly different.

The moon works in the smallest telescope. It's best viewed when it's not full, as the shadow will enhance the appearance of all the crates.

 

 

The only concern I have is with the "wow" factor.

Yes, indeed, everybody has different interests and expectations.

In another astronomy forum there was just a case of dissapointment as the galaxies, planets and stars are not whirling around in full color and HD as soon as you put your eye to the eyepiece.

With the stock eyepieces Jupiter will probably be as big as this ->>> O <---- on most screens ;-)

Oh, if sun observing is an issue, you will need a closed tube telescope and a special filter... else NEVER look into the sun, it's dangerous. Can't stress this enough. Instant blindness.

[chloe2005]

NO.....wont be looking at the Sun

[Schorhr]

any good?

 

http://www.ebay.co.uk/itm/IDEAL-FOR-XMAS-TELESCOPE-ORION-DOBSONIAN-SKYQUEST-TX4-5-INC-MOON-FILTER-PACK-/200970904147?pt=UK_Photography_Telescopes&hash=item2ecacca253

Yes and no; A dobsonian as said is simple and easy to use, this one's aperture ratio is a bit less critical then the short Heritage 130p, but smaller aperture and heavier too. The a 6x26 finder is not as user friendly as a red-dot-finder and you really have to watch out not to bid too much.

A 130mm or 150mm telescope can magnify a little higher, but overall a 4.5" (114mm) telescope is a nice starter device of course.

I have built 125/900 dobsonians for around 45gbp and a 114/900 tube costs about 70gpb (but on a weak tripod). As a 130mm telescope starts at around 110gpb, A good bid would probably be 50gbp, I don't know if I would go any higher then that for a used small dobsonian, especially If I where unable to try it first.

[LukeSkywatcher]

Having read all the posts here, i'm still a bit stuck as to what scope to say will be the best. I think the easiest one to use would be the Heritage 130P. Its within budget and its light and its pretty self-explaining in how to use it. I dont think your daughter wants to be doing 1-2-3 star alignment that comes with a Go-To scope,so a manual dob is the way to go. Also,unless she is quite tall, the Heritage will be a perfect size for her. 

[chloe2005]

Thanks Luke....greatly appreciated....

I think something like the Heritage is what i will seek

[Reeny]

In the meantime Chloe, load stellarium onto your computer, and try to borrow some binoculars - any size will do.

Andromeda is worthwhile for your daughter to find with binoculars.

She can do that now with some help from you.

Once you find it it's easy to recognise, even with the naked eye.

And when jupiter starts to appear at a more sociable time of night - she will be able to see the moons.

Stellarium has a search function for planets and other objects.

It helps me to navigate around with the binoculars before zooming in with the scope.

Navigation is the key to good viewing.

The binoculars are portable, and don't need setting up.

So no time or effort is lost if the clouds roll in after 5-10 minutes (the time it would normally take to assemble a tripod scope).

[leelee970]

From my own experience I was bought a Nexstar as a birthday present - it was OK, but the price was really for the GOTO and not the optics. (Mine was 60mm refractor - that is the diameter of the lens). The tripod was a little weak and flimsy and setting up the GOTO was not always a success.

 

But it did get me into Astronomy.

 

I soon bought a 10" (250mm) Dob - and still use it. Heavy to move around but very easy to set up. The only thing that may need to be done is collimation (aligning the mirrors up).

 

This scope led me to build an observatory with a GOTO mount and 8" (200mm) scope- no need to set up and take down.

 

My 8 and 5 year old girls love using the 10" Dob, so easy to use - and "Daddy" is the one that has to carry it out into the garden, and put it away.

 

I've also taken my scopes to the local school and the Dob is the one that is used the most by the children.

As I have said before the Dob is the best value for money in my opinion. It is simple, give great views and would last a long time.

[leelee970]

Stellarium is great.

[Reeny]

And it's free.

[chloe2005]

Ok......

Have downloaded Sterrerium on my computer....

What do i do now with it....does it need setting up to my location...if so, how do i do that

[ronin]

For what you describe I would go towards a refractor, they are a bit more intuitive for a child to use.

I am somewhat unsure of the small dobsonians for the situation you describe.

Not keen myself on the StarTravel 80's but one would do most of what you want and they have a wide view so easy to find things and they are in effect maintenance free and also robust. The drawback is they will show some colour on things like Jupiter and possible magnification may not be quite enough to get a nice view of Saturn.

Something like the Evostar 90 would do all you mention, but an Evostar 90 costs a bit more, not really aware of a longer focal length 80mm that is a reasonable cost available in the UK, Opticstar do one at £230 and then you still need bits to make it into a usable scope, so that is out of consideration. If 70mm is OK then there are a few available on the Alz/Az type mount they seem to be around the £100-120 price range.

[Reeny]

Move the mouse to the left hand side of the screen - and a side menu will pop up.

Top button (a compass star) is the location.

Enter Lincoln into the search bar, Uk is third from bottom.

Or search for a city / town which is nearer to you.

Enter and save as your default location.

I went on google earth, found my longitude & latitude, the entered my home town as a new location.

To be honest, the accuracy will be near enough for you if you use Lincoln.

Now go to the bottom menu bar.

Click the saturn logo, and the spiral logo next to it.

Now fast forward the clock to see what is viewable tonight.

Jupiter pops up around 1am

[Schorhr]

Ok......

 

Have downloaded Sterrerium on my computer....

 

What do i do now with it....does it need setting up to my location...if so, how do i do that

 

http://www.stellarium.org/wiki/index.php/FAQ#Using_Stellarium

There is also a bunch of Youtube video tutorials on stellarium :-)

 

For what you describe I would go towards a refractor, they are a bit more intuitive for a child to use.

I am somewhat unsure of the small dobsonians for the situation you describe.

 

Not keen myself on the StarTravel 80's but one would do most of what you want and they have a wide view so easy to find things and they are in effect maintenance free and also robust. The drawback is they will show some colour on things like Jupiter and possible magnification may not be quite enough to get a nice view of Saturn.

 

Something like the Evostar 90 would do all you mention, but an Evostar 90 costs a bit more, not really aware of a longer focal length 80mm that is a reasonable cost available in the UK, Opticstar do one at £230 and then you still need bits to make it into a usable scope, so that is out of consideration. If 70mm is OK then there are a few available on the Alz/Az type mount they seem to be around the £100-120 price range.

I have a bunch of 60 and 70mm refractors, and the 130p beats their performance on moon, jupiter and saturn despite it's relatively large obstruction.

I have not used a 80mm refractor, but I can't imagine it would beat the overall performance, also given the weight and price for a suitable mount. Those larger refractors do get heavy :-)

Also I don't think they are harder to use, really. How so? Just because their focuser is sideways?

[chloe2005]

Ok.......

Managed to get my lat long from my postcode off the net.....

Put it into the program as directed then pressed both icons followed by the advance time.....

May pressed it a few to many times as screen was a blur and quickly found myself in 2017.......

Managed to reset it and re used the time advance.........really very good

[Reeny]

Now you can plan your viewing around the TV schedule.

And when the weather closes in - you can see what you are missing.

[Schorhr]

Hehe. Some day some company will create a telescope that has a Stellarium mode, in case of clouds it'll just show a virtual sky

[mitchelln]

Hehe. Some day some company will create a telescope that has a Stellarium mode, in case of clouds it'll just show a virtual sky

Just stick some Google glasses on the end of a loo roll