Reflector v's Refractor telescope

[KerryThomas81]

So, I have been looking online for the last few days on and off at different telescopes. It seems the 2 most popular ones for beginners are either the Reflector or Refractor telescopes. 

I would like to hear people's views on these, and the experiences they have had if you wouldn't mind sharing, just to shine some more light on the subject (excuse the pun) 

I have been looking at a Skywatcher EXPLORER -150p (EQ3-2) 150mm  parabolic Newtonian reflector and a Startravel -120 f/5 (AZ-3) 4.75" refractor. Has anyone any experience with either of these telescopes? the brand and/or models?

Look forward to hearing back from you.

[Moonshane]

For me, the 150 Newtonian is a better all rounder but I'd recommend an alt az mount like the AZ4 with steel legs rather than the ali legs. The 120 star travel is nice but struggles at magnifications above about 100x

[KerryThomas81]

For me, the 150 Newtonian is a better all rounder but I'd recommend an alt az mount like the AZ4 with steel legs rather than the ali legs. The 120 star travel is nice but struggles at magnifications above about 100x

I have read of people filling the legs with fine grain sand to help stabilize the EQ mounts? I am just trying to gather as much information as possible before making my choice

[Cjg]

Kerry,

I've not owned or used both so will not offer an opinion. I notice that you have Kings Lynn as your location, I've met a few folks from the West Norfolk Astro who may have examples of those scopes in use..it would pay to visit them and have a look through /  at both examples. They are a friendly group based at a village hall at Tottenhill. 

You'll find their contact details at http://www.westnorfolkastro.co.uk/

Good luck!

Chris

[Cornelius Varley]

I have read of people filling the legs with fine grain sand to help stabilize the EQ mounts? I am just trying to gather as much information as possible before making my choice

The steel legs of the AZ4 shouldn't need filling. This tripod is the same as that used on some of the larger mounts and is very solid and stable

[Moonshane]

I have read of people filling the legs with fine grain sand to help stabilize the EQ mounts? I am just trying to gather as much information as possible before making my choice

you can but it's usually the head that struggles. Sand and optics is not a great combo.

[Steve Ward]

I'd say that the Skyliner 200P Dobsonian was a better "bang for buck" option than either of those for roughly the same outlay ... 

http://www.opticalvision.co.uk/astronomical_telescopes-sky-watcher-dobsonians/skyliner-200p.html

[KerryThomas81]

Kerry,

I've not owned or used both so will not offer an opinion. I notice that you have Kings Lynn as your location, I've met a few folks from the West Norfolk Astro who may have examples of those scopes in use..it would pay to visit them and have a look through /  at both examples. They are a friendly group based at a village hall at Tottenhill. 

You'll find their contact details at http://www.westnorfolkastro.co.uk/

Good luck!

Chris

I emailed them just today actually, to see about popping along one evening to meet with people and find out a bit more on getting started. I hope to hear back this week sometime. Thanks Chris

[laudropb]

+1 for the 200p Dob. Simple to use. No awkward eyepiece positions and a better all rounder.

[Peter Drew]

There are good refractors and reflectors for all aspects of astronomy. Size for size the reflectors are the best value and a 200mm Newtonian will always be the best bang for the buck. If you are just starting out this would be the best allrounder provided that you can manage the size. After gaining experience your next purchase might well be a refractor. I always cringe at the thought of filling sliding tripod legs with sand, sooner or later the sand is going to get in the wrong place. Hanging a weight from the tripod to help steady it is a better option IMO.

[Astro Imp]

I own and have used a 150P on a EQ3-2 and have had some great nights observing. However if I was starting again with the knowledge I have gained I wouldn't start with this combination for visual use. Using a Newtonian scope on an equatorial mount is just too much hassle, you are forever faffing around turning the scope in the rings to bring the eyepiece to a convenient position. I would think that the only use of an equatorial mount is for imaging and you would need something considerably more up market to pursue this branch of the hobby.

I would seriously consider the 200P Dob. mentioned above, you will see more and it will be much easier to use.

HTH

[cjdawson]

Let me lay out the options as I understand them.

There tends not to a be a huge amount to pick between the scopes optically.  A 120mm scope is 120mm whether it is refractor, reflector or something else..   Having said there are differences that you need to be aware of.

Firstly, Refractors tend to have a compromise as different wavelengths of light bend different amounts with refracted.  This can cause some distortion to the image - it's only small and for a small refractor (120mm is small in these terms) it'll be ok, but be aware it might be a thin.

Reflectors get around this as they don't bend the light, they reflect it.

In use, a refractor, will need to be on a tall tripod, as you look closer to the zenith, the eyepiece will get lower to the ground.   With a reflector, the eyepiece is at the opposite end, so as you raise the scope to the zenith, the eyepiece also gets higher.  With a long enough scope, you will end up needing a ladder to get to the eyepiece.  This is something that is governed by the focal length of the scope, and your own height.

Other than that, you then get into build qualiry - flimsy mounts need strengthening to stop the wobbles, etc.

[RikM]

I'd say that the Skyliner 200P Dobsonian was a better "bang for buck" option than either of those for roughly the same outlay ... 

http://www.opticalvision.co.uk/astronomical_telescopes-sky-watcher-dobsonians/skyliner-200p.html

 So would I. I have the 150P and AZ4 and it's a great combination, but a 200P Dobsonian is better in almost every way. I also have an EQ3-2 and I would say there is no advantage for an EQ mount for visual observing. altaz is so much simpler and more convenient.

[KerryThomas81]

So would I. I have the 150P and AZ4 and it's a great combination, but a 200P Dobsonian is better in almost every way. I also have an EQ3-2 and I would say there is no advantage for an EQ mount for visual observing. altaz is so much simpler and more convenient.

[mikeDnight]

I'd imagine you'd be disappointed with the star travel refractor as a general purpose scope. It is in reality a specialist rich field instrument and is limited to low powers. The reflectors mentioned above are a much better bet as all round instruments. If you want a refractor you'd really need to get one with a longer focal length than the star travel for it to be a good all rounder. Or, you could go for an ED apochromatic refractor, but the cost goes through the roof for this kind of scope.

The 6" Newtonian you mentioned in your original post has the advantage of being light weight and easily manageable, and is capable of providing you with years of enjoyment. The easier a scope is to use, the more often you'll be inclined to use it.

Mike

[paulastro]

The AZ4 is an alternative to a dobsonian if you don't want to use an equatorial for your reflector.  I use a SW 6inch F5 and it's very sturdy, quick to set up and use and easy to pick up the whole thing and move around if you need to avoid any obstructions.  The AZ4 is also useful for a variety of other scopes - useful if you have more than one.

[Mr Spock]

For the amount of money they cost, the 200 Dob is seriously good.

[Chipela]

I have liked the Skywatcher 150PDS + EQ5 combo a lot. It's easy to disassemble it to four pieces, 5 kilos each, so moving around and managing is easy.

I understand that equatorial mount is more complex than alt-az but it gives a special advantage: add later a single axis tracking motor (~100euros) and targets stay in view. This is very useful when sharing the view with someone (especially with high magnification).

Rough tracking doesn't need any precise alignment, it's enough that the RA axis points approximately to north.

[Alan64]

Hi Kerry,

Both telescopes would have their respective caveats...

The 120mm f/5 refractor would perform quite well for the dimmer, deep-space objects; but when turning it towards the Moon and planets, at f/5, it will exhibit quite a bit of chromatic aberration, or false colour, and would be reminiscent of a kaleidoscope in that event.  There are filters to minimise the effect, but at f/5, I wouldn't expect a satisfactory reduction, let alone an elimination.  An AZ4, with aluminum legs instead, would be lighter and more portable...

http://www.firstlightoptics.com/startravel/skywatcher-startravel-120t-ota.html

http://www.rothervalleyoptics.co.uk/skywatcher-az4-1-alt-az-mount-with-aluminium-tripod.html

Or, pair the refractor with an equatorial, perhaps an EQ5...

http://www.firstlightoptics.com/skywatcher-mounts/skywatcher-eq5-deluxe.html

...,and a single motor drive for its RA axis; for hands-free, automatic tracking of any object, whilst keeping same in the eyepiece's field-of-view for extended periods; for studying a moon's shadow-transit across the face of Jupiter; and even for casual, short-exposure astrophotography...

http://www.rothervalleyoptics.co.uk/skywatcher-ra-motor-drive-for-eq5-with-multi-speed-handset.html

Refractors require the least amount of maintenance, are optically unobstructed, and are the most durable of telescopic designs.

This 150mm f/5 Newtonian,instead, has a 2" two-speed focusser, and for ultra-fine focussing for the more difficult targets...

http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-ota.html

...and for only £26 more over the 150P, albeit when both are purchased separately.

A 150mm f/5 Newtonian would be a near, mirrored simulation of said refractor, but without the false colour.  Mirrored telescopes are apochromatic, meaning, totally free of false colour.  It, too, could be mounted on the linked AZ4 mount, but it would not need an EQ5 for visual, nor perhaps for casual imaging even.  An EQ3 could be had instead, and motorising its RA axis as well...

http://www.firstlightoptics.com/skywatcher-mounts/skywatcher-eq3-2-deluxe.html

http://www.rothervalleyoptics.co.uk/skywatcher-ra-motor-drive-for-eq3-2-with-multi-speed-handset.html

Newtonians require collimation; that is, simply aligning and aiming the primary mirror towards the secondary mirror, then ensuring that the secondary is aimed directly into the focusser and the eyepiece, like so...

http://www.company7.com/orion/graphics/NewtonianLightPath649499.jpg

Collimation instructions abound throughout the internet; for example... http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm ...along with assistance from the members of this site and others.

Collimation is not the beast as it might appear at first, is mastered soon enough, and for best image quality.

I have a 6" f/5 Newtonian, and by virtue of its apochromatic performance I'm able to routinely observe the bright Moon, the brighter of the planets and stars, at high magnifications, over 200x, and with no false colour whatsoever...

Cheers,

Alan

  

[RT65CB-SWL]

Hi Kerry and welcome to SGL.

If you purchase a refractor, buy a star diagonal too if it is not included, as it will make looking into the eyepiece easier.

If you purchase a Newtonian reflector, go for a dobsonian. Pros are...

1. low centre of gravity.

2. eyepiece does not rotate as you move the 'scope in azimuth, only altitude.

3. no false colour.

...or if you can afford a catadioptric reflector, ie Maksutov or SCT, again buy a star diagonal if not included.

Another optional purchase I would consider would be a variable Lunar/Moon filter.

[Alan64]

A Newtonian on an alt-azimuth doesn't get any better insofar as comfortable eye placement.  The optical tube of a 6" f/5 rotates quite easily and handily within its tube rings, I've found, and is most comfortable in comparison to the fixed focusser of a "Dobsonian".  I also find a mostly-metal mount far more durable in comparison to one of heavy, non-durable particle board.  Dobsonians, with their primary mirrors close to the ground, suffer more from thermal issues which compromise the images.  I have read of users using box fans to dispel thermal layers within the longer, ground-hugging optical tubes of Dobsonians.  This is especially problematic during the warmer months.  With a 6" f/5 positioned higher upon its mount, it and the observer enjoy much greater air circulation and thereby a faster acclimation; ready to observe in mere minutes instead of an hour or more.

A 6" f/5, with a focal-length of 750mm, whether a Newtonian or a refractor, is the closest one may come to a telescope that does it all, visually: the lower magnifications for deep space vistas, and the higher magnifications for the Moon and planets with the aid of a simple 2x barlow; most versatile, compact, portable, bright and powerful; all adjectives describing a travelling astro-master...

[KerryThomas81]

Thank you all for your advice. I decided to go for the Dobsonian 200p. Took it out the other night for the first time, and was not disappointed