90/900 SkyWatcher refractor on EQ2 VS 130/900 SkyWatcher newton on EQ2

[vilimovsky]

Greetings!

I'm planning to buy my first real scope, but because of a newborn child in the house i'm on a tight budget, around 200 pounds for scope and bits and pieces. Like all beginners i would like to do a little of everything, Solar system, binary stars and some DSO if possible . This two scope are readly avaliable at telescope centar near me and are in my price range, what say you oh mighty SGL collective

Thanks!

Vilimovsky

[jnb]

I say buy second hand. At that price new you will get an EQ2 mount which will be lightweight for either of those scopes. If the budget has to be £200 and it has to be new then while I am not a fan of them I would suggest looking at a dobsonian or a short tube refractor. Dobsonians have stable if limited mounts and short tube refractors put less strain on the mount.

[ronin]

The refractor is smaller in diameter then the reflector, which is the main negative point against it.

It will perform well and by the nature of a refractor should require no maintenance.

The reflector is greater diameter however for the one in question the mirror will be spherical, not a great problem if the tube is about 900mm long. You will also need to collimate the scope at intervals, not a great problem but it will be required, that means buying a collimator.

Check the physical length of the tube on the reflector.

Occasionally the focal length is 900mm and the tube is 500mm. This then means they put a barlow lens in the focuser to get the extra focal length. You would be best to avoid this type of scope, (Bird-Jones design).

If the reflector had stated 130P then I would be drawn more to that, without the "P" (parabolic) then I would go for the refractor even is smaller diameter.

Looking at other sites the 130/900 appears to be a standard reflector design so not a Bird-Jones.

[Cornelius Varley]

The Skywatcher 130/900 has a spherical mirror, but at this diameter the difference in performance between parabolic and spherical mirrors is negligible.

[nmoushon]

If you are going to stick between these two I would go with the reflector. You'll get a decent more amount of light so you'll be able to see more. I would also suggest looking second hand. This will save you a bit on your budget and will allow you to get an extra eye piece or two or a couple other extras.

[vilimovsky]

Thanks for detailed info, i think i'm going to try and up the ante to 300 pounds and see what i can get for that, if you have some recommendation for that price range do tell, oh and sadly it has to be from a shop. (Btw prices here are almost the sam as in UK)

[Schorhr]

The EQ2 or a bit more beefy Astro3 ("fake" EQ3) has  already trouble with a 130/650, I would say that's the limit if you don't want to cope with vibration at high magnifications..

.

If you just want to observe visually, consider a 150mm (6") dobsonain, or regarding saving a bit more, the 200mm (8") is great, as it will show spiral arms of some galaxies (under dark skies where the milky way is visible well) but even for planetary observation the higher resolution, light gathering and stable mount rocks... But you have to track in both directions by hand (easy, really).

Keep in mind you will need maps (print or just start with "turn left at orion"), a red lamp (preserving night vision), one or two additional eyepieces (10-27gbp, for example UWA 66 degree eyepieces, Seben Erfle or Plössl)...

Good luck choosing the right telescope :-)

If it needs to be portable, affordable, yet still stable: Heritage 130p.

Different apertures; 

http://clarkvision.com/visastro/m51-apert/

(under dark conditions, the impression of the galaxy after longer observation, using multiple magnifications to detect the fine details)

What you can epect to see in a small telescope

http://stargazerslounge.com/topic/196278-what-can-i-expect-to-see/

(no colorful images, poster sized images, yet stunning details once you get past that)

Influence of light pollution

http://www.perezmedia.net/beltofvenus/archives/001459.html

(and he orion nebula is one of the brightest DSO objects... faint galaxies won't even be visible within a city... only if the milky way is visible, you can expect to see a few details - see bortle scale or by counting the stars of ursa minor, to estimate the sky quality)

[purdo]

Hi Vilimovsky & Welcome to SGL.

I have the 8" (200P) Dobsonian bought for £300 including carriage. Great telescope.  To see what it looks like, click on First Light Optics logo at the top of the page, then on Telescopes - Skywatcher - Dobsonians.

[vilimovsky]

Thank you for links Schorhr! One question, is it possible to buy a good EQ mount and then transfer the OTA from dob mount to EQ later in the game?

[Schorhr]

Hi,

it is possible, but the newtonian telescopes on the dobsonians are usualy long and heavy (long focal length for easier viewing, better aperture Ratio to use cheap eyepieces...).

This will require you to get a larger, more expensive mount, and perhaps a focal reducer.

That can cost more then, say, a shorter f/5 telescope and eq mount.

Many use a large dobsonian telescope for visual (as it will Show more) and Get a smaller telescope on a eq mount for imaging. Ideally with a lower focal length to prevent frustration when beginning.

Getting a telescope for both visual and imaging often results in a compromise that ruins the fun.

If you just want tracking, visually, you can build or buy an EQ Platform to put your dobsonian on. It will track for about an hour and is good enough for visual purposes. While manually tracking is not hard, at magnifications over 200x a eq platform can make observing easier especially with difficult objects or if you plan on sketching stuff.

If you plan on taking snapshots of planets, this can be done with a dobsonian, it is a bit difficult to track manually though just by finder scope. I did it up to 2000mm focal length. You record a video, select the best frames, and stack those. Can be done.

For deepsky imaging, all you need is a camera with long exposure times or bulb mode, very simple barndoor mount (boards, hinges, threaded rod... Can be built for under 10£).

There are lots of amazing objects you can make visible that way, just using a lens between 18 and 200mm.

So what kind of imaging do you plan on doing, or just prefer an equatorial mount?

for visual, you will notice how easy a dobsonian is, and the focuser does not turn to odd places when panning.

[vilimovsky]

Well to be honest i'm afraid that with dobson i'll have to constantly "play" with the scope and that i'll be more concentrated on tracking than on observing, but this is noob talking so i'm probably wrong. How much do you really have to play with a dob?

My intentions with the scope are that of purely visual observing XD.

[Schorhr]

If visual is all you want, the dobsonian will be fine. Many Deepsky Objects will require less then 100x magnification, and then you have only move the dobsonian once in a while.

At 200x the Objects will slowly move through the field of view, with affordable 70 degree wide angle eyepieces that does work quite well.

You don't need to track it all the time, just let the object (such as Saturn) wander through the field of view, then gently nudge the dobsonian again to move it back into the view.

With magnifications hitting 300x you either want to get ultra wide angle eyepieces or consider a eq platform. Sadly, those cost around 300€ now, but that would be still cheaper then a EQ6 with motor, and for visual use, a eq platform is really nice and quickly set up (point north, put dobsonian ontop, turn motor on.).

If you want you can set up a telescope in stellarium and compare how fast an object passes through the field of view, for example with a

- 200/1200 telescope,

a 30mm 52 degree eyepiece (plössl, 15-30£),

a 30mm 70 degree (Erfle, 2" eyepiece, 50-80£),

- and a 6mm50 degree (plössl6 £)

- and 66 degree ( UWA 20-27£ ) eyepiece.

Of course moving the dobsonian is much smoother then with the arrow keys, so as allways, the software does not give a realistic impression but shows you the different transit times and field of views.

At 200-260x (66deg eyepiece) wich I often use for planets it can be a bit anoying at times, but not so badly that I would drag out my eq platform every time.

A dobsonian is so easy to use, stable and smooth to move, it neglects most downsides. Surely a EQ mount is nice, especially with motor tracking, but the moving focuser position is much more anoying (IMO).

[vilimovsky]

Oh one important thing that i forgot to write is that my primary observing spots are on gravel roads with some bigger chunks...

[Schorhr]

Usualy it's not hard to find a place to place a dobsonian, but one should not underestimate their size (though a 6" on a STABLE eq mount can weigh as much as a 8" dobsonian).

I put my dobsonians on grass, gravel, roads, whatever.

Worst case would be to remove a few larger chunks or use a heavy board, but I doub't that'll be neccesary.

With a 8" dobsonian you can see a lot of deepsky details that are not visible in 4 or 6". You won't regret it (if you have a realistic expectation such as the animated 3D galaxy animations from TV. :=) ).

[vilimovsky]

I expect fuzzy greys

A

fter some thinking i decided to go with 150/1200 SW  Skyliner Dobson, in the spec is said that it has Pyrex primary parabolic mirror, Cryford 2" focuser with an adapter to 1,25", it comes with 10 mm and  25 mm EP (it does not state FOV or maker), and with a 6x30 finder scope.

What else do you recommend to buy in terms of filters, eyepieces or collimator device?

[ollypenrice]

A simple Cheshire is a good collimator. A laser is quicker but you need a good one or they are not accurate.

You'll need a red light, ideally on your head, and some star charts. You can print your own from the free Stellarium prior to a night out or you could buy something like SkyAtlas 2000 by Wil Tirion. I don't get on with smaller ones but some people do.

Good choice of scope. Dobs are so nice to use.

Olly

[Schorhr]

So why the 6" over the 8", price? Because both dobsonians typically come with parabolic mirror.

The typical 10 and 25 eyepieces that come with most scopes are not turning you blind but are best to be to replaced in the long tem.

at the beginning they are fine, a collimation cap can do the trick and costs nothing or a few bucks if you buy one ready made.

A 6X30 finder scope is not a good choice, a Telrad or rigel quickfinder make locating things easier.

in the long term you will need a 2" overview eyepiece (at f/6 something like 30-36mm depending on your dark skies, at f/8 40mm for example. Type erfle works ok at those aperture ratios... Cost 60-80£ but show a nice wide angle field)

Other then overview eyepieces, a 6mm for 200x helps a lot. Nice for planets.

plössl are cheap but the short ones have way to little eye relief, but cost under 8£. Better are the 6mm UWA with 66 degree apparent field of view, 20-27£.