Looking for some general advice. Noob questions inside...

[smulx]

I've saved up a few questions instead of making different threads for little things, so these are the things that have confused me so far. Any advice at all is appreciated.

Why do some auto tracking mounts have different motor speeds? I would have thought they only needed to move at one speed to compensate for the earths rotation.

I know that a refractor is better for viewing things within the solar system, but how much better is it? For example, if I had an 8" reflector already, would a smaller ~5" refractor be noticeably better for closer objects?

I'm a bit confused about which mounts will auto track an object accurately. I've understood the difference between an Equiorial and Altazimuth, and it's the Equitorial I want to go for. But, it's not always clear which ones provide motorized auto tracking. Is it standard for a GOTO one to also provide a tracking function, or will the two things be mentioned separately? I think the Synscan and Syntrek functions on the skywatcher ones have something to do with this, but I'm still a bit confused. I hope that makes sense. I'll try to rephrase it if it doesn't.

Is the tracking required for photographing closer objects like the moon and planets, or are short exposures enough to get decent pictures for the closer things?

Finally, if I explain exactly what I want, hopefully someone will be able to provide some advice. Basically, I just don't want to end up with obsolete things that have ended up being a waste of money, For example, instead of buying loads of cheap things now and having to upgrade everything when I can afford it, I thought it would be best to buy fewer things but better quality. So instead of buying a cheap scope, cheap mount, cheap goto equipment and cheap camera, first I'm going to invest in a slightly better quality scope and mount. The one I was thinking about was a Skywatcher 200P 8" with an EQ5 Deluxe mount. And then eventually, I can upgrade the mount with a tracking system which I can use for photography, and I haven't ended up wasting any money by getting a completely new mount and discarding the old one. I'd prefer to get a Dobsonian now, but I'm thinking ahead and I don't think they can be easily upgraded. Does all this sound like a logical approach, or can anyone offer advice based on your experience when starting out?

Thanks!

[smulx]

After looking around a bit more it seems that all Dobsonian's only have altazimuth mounts, so are they never useful for capturing images of DSO's?

[Astro_Baby]

Hi and welcome - I added all my replies below but this is a personal viewpoint only and you have to remember everyones experience is different.

I've saved up a few questions instead of making different threads for little things, so these are the things that have confused me so far. Any advice at all is appreciated.

Ta very much -

Why do some auto tracking mounts have different motor speeds? I would have thought they only needed to move at one speed to compensate for the earths rotation.

Yes your right - they only really need one speed in an ideal world BUT because you may want to drive the scope to a nearby target or to make corrections to the scopes tracking you may want a slightly faster speed. Unless a scopes equaltorial mouint is accurately polar aligned (thats a topic in itself) there will be tracking errors and you will need a little bit of user input to adjust the scope hence the variable speeds. By the way remember the speeds of up to about x16 on a lot of mounts is VERY slow. Normal speed would take the scope 24 hours to perform a revolution so at x.16 it would take the scope 90 minutes to turn round once. In a nutshell x16 is useful but only for drive corrections NOT for moving around the sky - for that you need speeds up around x300

I know that a refractor is better for viewing things within the solar system, but how much better is it? For example, if I had an 8" reflector already, would a smaller ~5" refractor be noticeably better for closer objects?

Ohh tough question. SOme would say a long focal length refractor will perform better on planets and the mnoon than a modern fast reflector (and I'd be one of them by the way). However you could have a slow(er) reflector with a longer focal length and it would do as well. There are all sorts of abstract debates about whether a reflector is as efficient on planetary targets because of its central obstruction. In a nutshell a decent reflector is a good maid of all work whereas longish focal length refractors have their adherents for plenateray and double star views. Its a pretyyu touigh one to give a single opinion and everyone will have their own view of that I suspect.

I'm a bit confused about which mounts will auto track an object accurately. I've understood the difference between an Equiorial and Altazimuth, and it's the Equitorial I want to go for. But, it's not always clear which ones provide motorized auto tracking. Is it standard for a GOTO one to also provide a tracking function, or will the two things be mentioned separately? I think the Synscan and Syntrek functions on the skywatcher ones have something to do with this, but I'm still a bit confused. I hope that makes sense. I'll try to rephrase it if it doesn't.

GoTo and tracking are different. A GoTo scope will always do tracking as part of its functions whereas tracking mounts will only track (its down to you to find the object in the first place). Syntrek is essentially a 'slugged' GoTo mount. It has the high speed motors of a GoTo mount and most of the gubbins but not the GoTo handset which has the smarts in it for GoTo. GoTO mounts always have far faster motors (for high speed slewing) whereas tracking mounts (apart from Syntrek) most usually have slower motors.

Both equatorial mounts (EQ) and AltAz mounts can do both tracking and GoTo these days some motorised Alt/Az mounts mimic an EQ in the telecope motions. THese are ok for observing but cause probloems for atroimaging where you really need an equatorial mount. Imaging is a subject in its own right and I cant really offer any advice there.

Is the tracking required for photographing closer objects like the moon and planets, or are short exposures enough to get decent pictures for the closer things?

I'll leave that to the imaging boys and girls. A good book on imaging for the beginner is 'Making Evry Photon Count' and its been written by one of the forum members - the very estimable Steve Richards.

Finally, if I explain exactly what I want, hopefully someone will be able to provide some advice. Basically, I just don't want to end up with obsolete things that have ended up being a waste of money, For example, instead of buying loads of cheap things now and having to upgrade everything when I can afford it, I thought it would be best to buy fewer things but better quality. So instead of buying a cheap scope, cheap mount, cheap goto equipment and cheap camera, first I'm going to invest in a slightly better quality scope and mount. The one I was thinking about was a Skywatcher 200P 8" with an EQ5 Deluxe mount. And then eventually, I can upgrade the mount with a tracking system which I can use for photography, and I haven't ended up wasting any money by getting a completely new mount and discarding the old one. I'd prefer to get a Dobsonian now, but I'm thinking ahead and I don't think they can be easily upgraded. Does all this sound like a logical approach, or can anyone offer advice based on your experience when starting out?

Whew - ok - although planning for the futue is good unless you literally have tons of money the bottom line is WHETEVER you buy you will want to upgrade or exchange later on.

For me - I bought a cheap scope to start with (SKyWatcher 130) while I worked out what I REALLY wanted to do. Haveing decided I bought something a bit more expensive (Skywatcher 200 on an HEQ5). The fact is even the HEQ5 isnt really toigh enough for what I want but I have to be portable and an EQ6 is just a bit too heavy. You could mount a Dob tube later on onto an EQ6 if you wanted but the fact is the market is getting better and better and by the time you took that step you may just want to get a whole new rig.

People always advise people to get the best they can afford. Its sound advice in some ways but ignores the fact a beginner may not have the faintest idea of what they want to do. Lots of people start off assuming they will do imaging (I am going to be controversial and suggest that while imaging is enormously satisfying for many people its cost and challenges have the power to put people off the hobby altogether). A few months later the would be imager gets fed up because its tough and find they have the wrong gear. SImilarly observers often assume they will want the most powerful eyepiece - if they push off and buy a 3.8mm Ethos with a price tag of £500 and then find powerful mag isn'y any use to them then they mau hev the best power eyepiece going but its no use to them and they have wasted their cash. Thats why its so hard to advise a beginner.

I would seriously sugget getting along to an astro society or have a talk with a decent dealer like FLO before you part with cash or just hang around the forum and see what issues people have with their gear.

MORALITY TALE from the book of astro - Yea I was a reflector fan and deep sky observer but a few months back in the time of the summer an agent of mephistopheles sold me a TAL refractor as a piece of room decor, Get thee hence oh tempter I said but three times did he offer me the scope known as the TAL-100RS - FInally I weakened in my heart I got to using it and found it was good - verily. Now I almost never use the reflector because I enjoy the views with my smaller 'frac and have renounced the false faith of them that use reflectors. And verily did I sayeth unto the multitudes 'look mate it renders planets better'- and some astro fans did rend their clothes and gnash their teeth and sayeth I am barmy (yea I probably am). And I came at last to a place caled 'the observing site' and there I contemplated the many scopes I have owned and wept for I would have savthe myself a fortune had I bought that which I would not even consider when I started. - Here endeth the lesson - let us look at our eyepieces and sayeth 'if only I hade one more - amen'

Hope all of that is some small help.

Thanks!

[Astro_Baby]

Nope - Dobs are never used for DSO work. Deep Sky imaging requires long exposures and that means EQ mounts and tons of time, patience and equipment most usually - but thats really a question for the imaging folk.

[John]

After looking around a bit more it seems that all Dobsonian's only have altazimuth mounts, so are they never useful for capturing images of DSO's?

A dobsonian scope uses the same optical tube (ie: the same miror layout) as a newtonian but on a simple mount - it's the low cost but effective mount thats the innovation (or was when it was developed by John Dobson in the 1950's).

Because the mount is simple, you get the maximum amount of aperture for your money with the dobsonian scopes.

They are excellent for observing, particularly low to medium power views of deep sky objects but not suited for anything other simple "snapshot" type imaging of the moon and brightest planets.

[brantuk]

I have a dob for visual, a small eq mounted refractor for wide field imaging, and an SCT for both visual and imaging/guiding. It's dificult to find a single scope that satisfies all projected needs.

You'll get good visual and imaging on a fairly advanced eq mount perhaps with a large aperture newt or sct on it. You'd want to budget £1500 to £2K for that sort of set up new. Otherwise you'll probably have to compromise.

Buying second hand from other astronomers is a good way to go. Plenty of bargains to be had but you need to know what you're looking for to save 30% to 40% of those prices.

To gain that knowledge I'd suggest a cheaper set up whilst you learn the sky. You might also like to dable in a bit of AP with a webcam or dslr if you have one. Learn as much as poss about scope types, ep's, photo processing, techniques, etc. Join a local astro soc and/or get to a few star parties - you'll get a much better idea of what you eventually aspire to.

There's nothing wrong with a 6" or 8" newt on a HEQ5/6 mount for well under a grand s/h.

Meantime ask as many specific questions here as you like - you're allways guaranteed a quality answer.

All the best

[smulx]

Hope all of that is some small help.

That was a very large help, definitely not small. Thanks for going in to so much detail

[smulx]

A dobsonian scope uses the same optical tube (ie: the same miror layout) as a newtonian but on a simple mount - it's the low cost but effective mount thats the innovation (or was when it was developed by John Dobson in the 1950's).

Because the mount is simple, you get the maximum amount of aperture for your money with the dobsonian scopes.

They are excellent for observing, particularly low to medium power views of deep sky objects but not suited for anything other simple "snapshot" type imaging of the moon and brightest planets.

Makes sense, thanks. Is it possible to fit them to a proper equatorial mount? I've never actually seen one but I've read that they're pretty big so I wasn't sure if this would be too awkward to do.

[smulx]

I have a dob for visual, a small eq mounted refractor for wide field imaging, and an SCT for both visual and imaging/guiding. It's dificult to find a single scope that satisfies all projected needs.

You'll get good visual and imaging on a fairly advanced eq mount perhaps with a large aperture newt or sct on it. You'd want to budget £1500 to £2K for that sort of set up new. Otherwise you'll probably have to compromise.

Buying second hand from other astronomers is a good way to go. Plenty of bargains to be had but you need to know what you're looking for to save 30% to 40% of those prices.

To gain that knowledge I'd suggest a cheaper set up whilst you learn the sky. You might also like to dable in a bit of AP with a webcam or dslr if you have one. Learn as much as poss about scope types, ep's, photo processing, techniques, etc. Join a local astro soc and/or get to a few star parties - you'll get a much better idea of what you eventually aspire to.

There's nothing wrong with a 6" or 8" newt on a HEQ5/6 mount for well under a grand s/h.

Meantime ask as many specific questions here as you like - you're allways guaranteed a quality answer.

All the best

Thanks for the input, that's actually what I was beginning to think. It's probably best if I forgot about the imaging for now and blow all my money on a decent Dob with some good EP's.

What's so good about the SCT's? Is it just much higher quality?

[Astro_Baby]

Really more about portability than anything else.

[smulx]

Really more about portability than anything else.

Would an 8" Dob be awkward to move around? I've never seen one but I've read that they're pretty big.

[John]

Makes sense, thanks. Is it possible to fit them to a proper equatorial mount? I've never actually seen one but I've read that they're pretty big so I wasn't sure if this would be too awkward to do.

Well it's the tube containing the optics that you would fit to the equatorial mount - it's not difficult as they use the same tubes as the equatorial scopes - you would need to buy a pair of tube rings and a thing called a dovetail bar which is what clamps into the equatorial mount.

An 8" dobsonian is more portable, in my opinion, than an 8" equatorially mounted scope. Takes up less room when not in use as well.

[brantuk]

SCT's and Maks tend to be used as planet killers - very sharp and crisp. Some come on eq mounts - many on alt/az. They can be used on dso's too so are good general all rounders. If they're on alt/az they can often be wedged for eq viewing - but affordable wedges vary in quality and can be a pain to set up for imaging. Even then tracking corrections still have to be made in two planes rather than one unless the alignment is absolutely spot on accurate. You need careful consideration of your objectives before blowing money on them cos they're quite expensive per inch of aperture.

Me? I love mine lol

[Astro_Baby]

Well an 8" dob would be typically about 10" wide - a scope is always a bit bigger than it mirror size and around 1.5m long (very roughly). The thing to watch is the weight because the mirros can get quite heavy. I dont think a 10" woulkd be all that bad but as a telescope mirror gets bigger it gets lots heavier in the process.

There are what is called Flextubes (Skywatcher make them) where the telescope sort of telescopes down in size and there are dobs where you can collapse the tube by removing the poles holding t together - its hard to explain but take a look here

Lightbridge - LightBridge 10" Truss Dobsonian

and you can see a truss tube type design where the poles are removable to allow the scope to be transported.

[smulx]

One of the flextube ones is actually on my list of possibilities for one to buy. I live in a heavily light polluted area so the extra space would be a bonus for travelling outside of the town.

I'd just pretty much made up my mind to get an 8" Dob, then I realised that the Skywatcher I was looking at has the same aperture and is only £100 more and it has an EQ5 mount included. Hmmm.

[brantuk]

My flextube is the 300 (12") and it has a 24" diameter base and stands 45-46" high when collapsed down. The OTA is quite heavy but manageable - same for the base. If you're fit and healthy it's not too much trouble to put in the car - but this size needs a Volvo estate at least. The 10" is obviously a bit smaller. They're great vfm per inch of aperture but you need to see one in the flesh to judge for yourself.

Most scopes are bigger than they look in the pictures so you so do check out size, weight, and portability