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JOC

What do I need to buy please?

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"Nexstar 6 SE or Sky watcher star discovery 150P there appears to be a significant difference in price for two 6" instruments - can someone explain the probable quality differences and if one is better than the other and why please?"

Aperture size is merely one attribute of a scope. One of those is an Sct which has a long focal length and slow focal ratio on alt/az mount - good for sharp contrasty views of planets and moon. The 150P is a newtonian with a shorter focal length and faster focal ratio on an EQ mount - better for peering at dso's and maybe a little long exposure photography. Of course you can do both observing and imaging with both scopes - but they both have their advantages and disads for either practise.

My advice would be to do a lot of research first - took me 3mths reading and asking questions before I bought my first scope. It helps if you can get along to an observing session with a local club - you'll learn a lot very quickly and see a wide variety of scopes from which to choose. I know you don't want to do that - but it really is the better way to avoid expensive mistakes. Or pop to an astro shop and spend half a day with a knowledgeable assistant who will advise - but bear in mind they also want to make a sale. Hth :)

 

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To clarify, The Star Discovery is a 150p f5 reflector telescope but it is not on an EQ mount. The Star Discovery 150p comes on a Alt-Az goto mount just like the 6SE except also has the advantage of freedome find.

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D'ohh - thanks HK - yes it's a alt/az goto. My slip. lol 

OP - Please discard my comments about EQ mount for this scope - the major difference is newt vs Sct. :)

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18 minutes ago, happy-kat said:

To clarify, The Star Discovery is a 150p f5 reflector telescope but it is not on an EQ mount. The Star Discovery 150p comes on a Alt-Az goto mount just like the 6SE except also has the advantage of freedome find.

One of the problems with threads like this is that they can often end up with a bewildering array of options and suggestions.

The other problem is that there is no such thing as a right or wrong answer. What delights one person might be frustrating to another.

Going to see the physical size of the scopes does make some sense, as once you get to the 8" and above they get big quickly.

I think it is worth doing some further research  on the differences between scope types, specifically SCTs and Newtonians. Briefly:

Newtonians

Pros

Relatively simple and cost effective

Open tube cools quite quickly

Shorter focal lengths give a wider field of view, easier to find objects and fit larger ones into the field

Primary is relatively protected from dew although the secondary can still dew up. A dew shield helps this.

No chromatic abberation

Cons

Require collimating regularly, although once learned this is a quickly process

Image is upside down, can be confusing

Faster scopes can be more demanding on eyepieces and will show coma

 

SCTs

Pros

Compact design, easy to transport

Long focal length is good for planets, moon and smaller DSOs

Slower focal ratio means it is possible to use cheaper eyepiece designs

No coma

Collimation tends to be more stable and only occasionally needs adjusting

No chromatic abberation

 

Cons

Slow to cool due to closed tube design

Front plate prone to dewing up, will need a dew shield and possibly heated dew strap

Narrow field of view can make finding things more difficult, and it is not possible to fit larger objects into the field of view

Image is upright but left/right reversed, may also be confusing ;)

 

As neither a pro or a con, with the Newtonian you look into the eyepiece from the side, at the top of the tube, with an SCT you look into the eyepiece at the rear of the scope. Both can end up in slightly awkward positions depending upon where you are looking in the sky.

Perhaps have a look into these comments and then see what you are drawn to. Do come back and ask more questions.

Both of the suggestions are valid i.e. 6SE and 150 Discovery I believe, and would cater for your requirements.

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I agree with "super giant" :icon_flower:

If you decide to go for the 6SE (or any SCT type scope) you will without question need a dew shield as they mist up very quickly. Dew shields can also be purchased from FLO or you can make one yourself.

The 6SE was my first telescope and it was both easy to use and great to look through, be warned though as it will hook you up like a fish for bigger and better views....then your life and wallet will never be the same again :hello:

Edited by Pig
Flower smiley added

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The OP needs to be think on what they require now and what they may require or like to do in the future.

The 8" dobsonian (200P) will get them a good view of the sky and allow them to see a great deal, the negative aspect is that the user has to locate everything and then keep it in view while they observe. The action will come but it may not be immediate. Also finding say M13 then passing the scope to someone else means that M13 will likely no longer be in view. Something will have moved. Like everything each scope has their positive and negative aspects.

If there is an idea of getting images then really that "restricts" the choice (in a way makes it easier) to an equitorial mount with motors and most likely with goto. Least for imaging would be something like an EQ5 and they are over £500 just for the mount.

I have a Bresser AR 102S sat here and that is a good all round scope, for a bit less CA they do a longer version, but the 102 seems a good entry scope. The CA would knock it out of the imaging in a strict sense but you can add a DSLR and play/practise. The field of view is good. Drawback of the 102 (or similar) is that it does not deliver the greatest magnification, neither does it deliver the largest aperture, but it does what it does well and easily.

Problem is that equipment is getting costly. People are sort of expecting a goto these days and a goto mount of reasonable entry level is something like the EQ5 (£530) or the iOptron CEM25 (£800). The EQ3-2 is £330 but is really too lightweight for what many people intend to eventually add to it or use it for. The iOptron SmartEQ is again nice but appearsto lack the carrying capacity. iOptron need something around the 8 to 9Kg capacity (20lbs). A 102S and an EQ5 comes to £800 and that is these days getting to be starter level.

The OP also may have to realise that the scope is the start. Almost immedialy additional eyepieces are required. I would simply say use the supplied items but expect to purchase new ones for everything. Minimal I suggest is something like the BST's at 8mm, 12mm and 25mm so £150. I suspect there are many that have a more costly collection of eyepieces then they do a collection of scopes.

Also I will suggest that marketing claims and "rules" be ignored. Many say 2x the diameter in mm for magnification. I suggest that you just expect that the maximum is simply the diameter in mm, not 2x of it. Most scopes produce that and anything above it is a bonus. That way you will not be disappointed.

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Imaging does not have to have an EQ mount but you must be aware of and accept the limatations that a motorised Alt-Az mount gives.

Nigel G uses the star discovery mount with the 150p and The Admiral uses the SE mount with a refractor, see this thread of how far they are pushing the imaging limits of those mounts which you are considering, though they are bouncing on the limiter, as are members SteveNickolls and Filroden who also post on that thread.

link here

There is no one size fits all, it is about finding the best match for what you need be it space, weight, portability, intended use etc. I would love a 200p but for me I do not have the space or capability to get it outside and it wont give me the imaging taste I'm after so I choose something else.

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As far as I'm aware the OP has not talked about deep sky imaging so an AltAz goto would be perfectly adequate visual and even for short exposure planetary or lunar imaging

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And welcome to the world of astronomy JOC!!!

Once you have your score we will bamboozle you with eyepieces!

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I would bet the SW 150P has better optics...at least as a system. The SCT uses more elements in its design and each one has the possibility to degrade the view. The long FL of the SCT has pro's and cons as well.

Overall a SW200mm dob would outperform the 6" SCT IMHO.

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Wow, what a helpful group of people - I like a lively forum all with folks willing to chip in and help a novice.  I've watched all the Sky watcher star discovery 150P link that was posted on Page 1, and I am tending to the view that it would probably be quite sufficient for what I'm looking for.  The Nexstar 6 SE may be the icing on the cake out of the two of them, but it is considerably more cash up front until I see how I get on with things.  The reviewer did seem quite keen on the 150P and wasn't beyond pointing out its short-comings, and although some might see it as a problem in waiting not having to collimate (I've looked up what this means) the main mirror may be easier for a beginner to get to grips with.  It also appeared that it was set up to have a bash at photography if I wanted to try it out.  I think the motorised goto drives are going to be more my cup-of tea - the easier it is to find things the more immediately attractive the whole thing could be.  I note that out of the two the Nexstar has been recommended as better for the planets due to longer focal length, whilst the 150P was more generally suitable. 

If I went down the 150P route, what sort of images might I reasonably see with the standard set-up.  Are telescopes at this level going to bring up something like any form of detail on something as distant as Jupiter - I can remember counting moons on the ex's old one, but they were only dots of light and the planet was just a vaguely orange disk, for example would I be able to see the swirl of a relatively close nebula, maybe colours - that sort of thing or do you really have chuck serious cash at this to get that level of detail.  OK, I know I won't have Hubble in the back yard, and of course the atmosphere is always going to be a bug-bear, but at this sort of price point (which is more than I may have paid for the ex's one) am I still in the class of 'dots of light', or can I expect to see some level of detail in the more distant objects (i.e. local planets and possibly beyond).  I am in the countryside, no street lights, 3 miles+ from the nearest medium size town and can point out over the direction of sea - we are not pristinely dark skies, but we get good stars on a clear night and I imagine are in a better position than a lot of folks.

Thank you all for your inputs, you all sound a great bunch of folks, esp. as this is probably the hundred and umpteenth time such a question has been asked.

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Good stuff, glad you seem to be finding your way to a good decision!

Sounds like your skies are better than most, and that is actually what makes most difference, a small scope will show plenty under a dark sky.

The 150P will actually not be significantly worse on planets than the SCT, but you will need to use shorter focal length eyepieces and these can tend to be a bit tighter on eye relief, certainly in the simpler/cheaper designs such as plossls.

In terms of what you can see, colour is pretty much out except for coloured stars which can be nice. You may catch some subtle colours on planets. When it is best placed, you should be able to see the two main surface bands on Jupiter (the Equatorial Belts), you can also see shadow transits of the moons and the Great Red Spot. You won't see the Galilean moons as anything other than points of light.

On Saturn you will see the rings, the separation between rings and the planet, probably the moon Titan and possibly some surface banding.

Everything else will be shades of grey, but if you understand what you are looking at then it is pretty amazing. Galaxies, open clusters of stars, globular clusters, nebulae and planetary nebulae, all should be possible.

M42, the Orion Nebula is probably the most easily seen nebula and will certainly show plenty of detail.

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Afraid not being a photographer I can't speak on what you might expect to get straight out of the box however I have seen some cracking photos taken with this scope of Jupiter and Saturn using a modified webcam and you will also get some great close up shots of the moon just by amming your phone down the eyepiece.

As for the collimation there is actually a little play in the primary mirror which lets you collimate it slightly which I have just finished doing on mine.

As for what you will see with this scope then as said above you will get the rings of Saturn and some good detail on Jupiter including the great red spot. Nebula's won't be a problem-the Orion nebula is one of those 'wow factor' targets and looks great thorough this scope and invest in a nebula filter and you will see plenty more. If you are interested in the limit of this unit then you may be interested that i recently located the famous 'whirlpool galaxy' , which at a distance of approx 26 million light years away ( 1 ly=aprox 6 trillion miles!) I didn't think was to shabby a distance to see when standing in my own back garden!!

Or is you just want to explore your self then you always have the 'point and look' option. Hope this helps.

Edited by popeye85

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If you are thinking of using your DSLR the best thing to do is take the telescope off the mount and use your DSLR with a lens. I think you get an adaptor in the box for mounting a camera to the mount.

Why because the focuser on the star discovery 150p needs a DIY job/hack (invalidate arranty) on it before a DSLR will reach focus. But a webcam will work great and is best suited to image planets.

If you really get into imaging you can always get other equipment in the future and keep what you chose now as the grab and get out there quicker gear.

Edited by happy-kat

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4 hours ago, JOC said:

  ........Are telescopes at this level going to bring up something like any form of detail on something as distant as Jupiter - I can remember counting moons on the ex's old one, but they were only dots of light and the planet was just a vaguely orange disk...........

I don't see why you should not see something with the 150P,  though I have not used one.
What I can say is,  I have seen the shadow of a Moon on the face of Jupiter, a perfect black spot, and  both  weather bands visible across the Planet but only for a few seconds that conditions allow, and the GRS! Great Red Spot, which is more of an orange/brown, blended into the weather bands, but the shape gives it away on a good night, but all this from a 200P. That memory is still  firmly etched till the next time.
Of Jupiter's Moons, no details are visible to my eyes, just points of light, But Jupiter is detailed. I would like to see Jupiter through a 12" to see how much bigger the image is compared to my 8". 

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Thanks all, I can feel a 150P coalescing as a purchase choice.  I'm a 'want to get started quickly type person', and will probably buy soon, but I am glad I came on to a forum and asked for some opinions as I realy didn't know where to start and I do like to feel that if I buy something I am doing so with a bit of research.  It is so good of you all to entertain yet another, what do I buy thread.  I'll keep checking back in case someone really has an opinion that I wouldn't be well served as a beginner with a 150P, but I think that's the choice at this moment in time.  So what is the next thread.....what eye pieces shall I buy, what shall I try to find to view............, what filters will I need (do the filters fit over the eye-pieces or over the lenses/mirrors?), how do I stop the credit card collapsing..............!!!!???

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If you like the 150P,  get the 200P. You won't regret it.
They come about second hand as/when folk upgrade to bigger scopes ( Aperture Fever ?) the desire to get more.  I just think the 200P (8") will last longer than the 150P  (6").
I was certain I was going out to get the 12" last Christmas, but the 8" may be all I need? Going larger has both merit and pitfalls? ie. cost weight size for portability. 

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My 130p revealed 5 like bands on Jupiter and I watched a moon's shadow transit as described above as a black dot, generally see the two main bands I think that night must have been exceptional seeing.

Not everyone gets aperature fever and you won't know whether you'll get it until you know. :-) on the plus side your dark location works in your favour.

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8 hours ago, JOC said:

how do I stop the credit card collapsing..............!!!!???

If there is an issue with the credit card... I would put the project on hold until the situation improves.

Edited by N3ptune

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No Issues with the credit card as the project commences - I just wondered how easily you can get hooked on constantly 'improving' things!  I suspect the problem all us novices have is being seduced by colour enhanced images taken by super-scopes in the media, and then wanting some measure of something similar on a home system, which I guess is never a likely thing to happen.

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It's not so much "colour enhanced" as "correctly coloured" according to wavelengths of light and combinations through filters. But then what does "correct" mean? It's only correct for our eyes - an alien may see things differently. But you can get some great images from your back yard - just look through the imaging sections - some of the guys n gals do fabulous work imaging - often better than magazines and tv.

But you do need the imaging gear to do it - expensive optics, mounts, filters, cameras etc. The eye can't see the sort of colours that cameras and long exposure can - it's impossible - so expect only blacks, whites, and shades of grey at the eyepiece - for all but a few dso's, planets, and the sun. :)

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Hi Brantuk  - duly noted, thank you, N.B.  I've no initial intention of viewing the sun - that sounds plenty dangerous without sufficient special kit! 

Picking up on something that was mentioned above re: taking pictures.  I understood that I can use the goto mount of a 150P to take pictures with my DSLR - is this understanding correct?  I assumed that you would need a system to take pictures of stars through a telescope.  I have obtained quite passable and pleasing images of the moon through my DSLR mounted on a standard photographic tripod, but I always assumed that this was the moon was bright enough to generate sufficient light and because it is a sufficiently large object to point the camera at.

12463678823_ec5a289eb9_z.jpg

What do you think?  I was quite chuffed with the image.  I found instructions online and just set the exposure and aperture to what it said and popped it on it onto the tripod with a cable release to take away the vibration.  I own a canon T3 Rebel (EOS 100D) - I have a 18-55mm and a 55-250mm lens. 

Does a camera like this posses sufficient magnification to take pictures of stars/nebula's without focussing through a telescope, and therefore does the mounting of it on a goto tripod allow it to track the stars during a long exposure?  In short - I am most intrigued that I might be able to take photos of the night sky with the 150P set-up even though (as I am sure you can tell) I don't have the first idea of how I'd do so.

Edited by JOC

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Using an alt-az tripod you can get anything from 10 seconds to 45 seconds depending where in the sky you point. Some directions the earth's rotation is more apparent so star streaking happens faster. Some DSO are very low light emission and those exposure lengths are not long enough to show them but many are bright enough. Longer exposure can only be done on a substantial equatorial mount which would eat your original budget in one go and not be as portable and light as you really want a very stable mount and that isn't going to be light. To see what members are achieving with their motorised Alt-az mounts check out the no eq challenge thread (one member Nigel G is using that mount with either the 150p (but he did hack the focuser ...) or a camera lens)). 55mm gives great wide field I used a lens that size for comet lovejoy.

Your camera is fine and can either be used directly with a telescope (not all will reach focus with a dslr) or with camera lenses. Ebay great source for vintage manual lenses quite cheap it is surprising what a 200mm lens can show.

 

Edited by happy-kat

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