Ok, I narrowed down to two choices, I think...

[ryouko]

Hello all!,

I am new to this hobby, and have been doing quite a bit of research. I have been quite interested into the larger truss dob scopes due mainly to the large size and yet the portablility they offer. I myself at first was interested into the astrophotography, but after carefull review of the type of equipment, and the budget that follows, I think I will just follow the advice that I have got from the post I left in the welcome section.

I know that these larger scopes are probably not "really" good for the beginner. I am sure the setup and take down are also a little inconvenient at times, yet, with all the reviews I have been reading, it seems to me that the little inconvenience is well worth the view. I personally have never looked through, or even seen one of these in person. So, I will like to get opinions from the ones that have had experiences with these types of scoopes.

From the first post, my first choice was the meade lightbridge. I figure the 12" would probably be the best of both the 10" and 16". The 16" seems to be a little pricy and the 12" is only a few more than the 10". I read a lot on the meade lightbridge to find that not only is it a good scope but can be modded quite easily. I myself being the mechanical type find this to be a good project to start on. Though, I also want one that is good right out of the box (as I am guilty of the impatience, including with new "toys" like this!)

My other choice that I have stumbled upon is the Orion Skyquest XX12i, which features a computerized aide in finding sites in the sky easier. Now I don't know quite well how this system works and if it is any good (including for a beginner like me) but could be a little help in enjoying the sites more than just trying to find them. I can't quite find many reviews on this scope, so compared to the meade lightbridge, what would all of your opions be on these scopes?

Keep in mind, yes I am new, and fairly ignorant in the subject. I find this hobby to be quite interesting, and something I would like to at least try before I say I do or do not like. This hobby also seem like one would find many new people and learn new things on the way, so why not!

[ollypenrice]

A big Dob can get you into the faint objects where a little help in navigating might be very useful. The argument agaisnt this is that you might learn less, though some feel aid is a help to learning. I think you will get 'fors' and 'againsts' on this thread and also someone is bound to find a third suggestion!!! I would say maybe yes, get the aided navigation.

Olly

[gedmac]

a large dob is ideal for a beginner.........just choose the size that matches your criteria,ie portability,weight,where you want to view:rolleyes:

[gedmac]

a couple of links for you

Dobsonians - Skywatcher Skyliner 300P FlexTube Dobsonian and Dobsonians - Skywatcher Skyliner 300P Dobsonian the no truss is quite a bit cheaper but the portability would be alot less:cool:

[Chris H]

I have the Orion XT10i with the object locator and it is an excellent system.

With regard to the 12" scope I would really recommend that you try and see one in the flesh before buying they are bigger than you might expect. My advice go for a 10" perfect balance between aperture and manageability. Also if you want it too work out of the box these Dobs require collimation and if its a truss design then they require collimation every time you assemble them. A solid tube 10" Dob would require less frequent adjustment the 8" even less again.

[NGC 1502]

I agree with Chris, post #5. Best to try before you buy. If you can get

along to an astronomy club or star party, that would be good.

Regards, Ed.

[thommo10]

I agree with Ed & Chris I would look at a scope in the flesh so to speak first, further more I would go for a non- motorised equatorial mount so you can learn the co-ordinates of objects in RA and DEC this is usefull when reading astronomical mags, you can always upgrade the mount later to a goto if you wish.

[Dave-Ryan]

You sound like I was when I was thinking about buying a telescope 6 years ago.

I had no books or knowledge of where to find anything so I bought a goto telescope and am glad I did because I doubt I would still have the interest today if I didn't.

For people like us an instant hit helps.

[JamesM]

I would at least go and have a look at the the different sized scopes to see what you feel you could manage if transporting it is part of the equation. Certainly some form of tracking is helpful especially at higher magnifications as the objects will move across the field of view quicker. Of course this could be countered by an eyepiece with a wider field of view but I guess you may feel that you've spent a bit of money and will want to get some observing under your belt before buying any more kit.

As a relative new person I am in the camp that argues that GOTO is really useful. Sure there is virtue in finding things manually and it does teach you a lot but given the weather sometimes, I always want to maximise my viewing opportunities to the full so I would go for it now as it is cheaper if it is already installed than it is to add it at a later date. Stellarium can provide you with altazimuth coordinates for objects if you want to use your drives manually.

With all these things, deciding from the start with all that research what you 'really' want is the best and cheapest way of going about it rather than buying and reselling towards what you want!

Clear skies

James

[ryouko]

Thank you for all the advice, I will be honest, though, I am a little impulsive about buying! It sounds to me that the biggest issue with these two scopes is more of the "goto" feature than the optics. In my opinion, and keep in mind of my ignorance, is more about the optics. Being an amateur photographer here of terrestrial type of course , when I look at a lens to purchase, I look at the focal length and aperture. So far the aperture of the Orion is f4.5, where the aperture of the meade lb is f5 , now I don't know if .1 would count, as when I shoot that does not have much of an affect for my photography. Now we are talking about viewing things that are light years away, so .1 might make an affect. Yet, I can't quite get over what the focal length is. The meade is around 1524mm, the orion skyquest sits at 1500mm and so does the skywatcher skyliner 300p which is also at f5. So I am not thinking that the 24mm will make much a difference, but I don't know overall which is the best. So far the LB is the highest focal length and the orion xx12 has the best aperture.

Now portability is no issues with me. Usually when I do go camping and what not, I take my rover which has plenty of room for any of these scopes. If I did have a good budget, I would have went with the 16" meade lightbridge, but that is getting to spendy for me. As I have said earlier, I am an impulsive buyer, and that 16" looks quite tempting. I figure the 12" would be a better overall buy seeing that I am a beginner and that the budget is not all the way up there. There is one thing, though, that I like about the skywatcher skyliner, is that it has direct slr camera hookup, which is what I wanted in the first place.

To gedmac, is the skywatcher skyliner 300p very sturdy? It looks to me the truss support is a little light, where the other ones add diagonal support also.

[pvaz]

There's a bit of a confusion there, which I also faced, when I started in astronomy as I also had some photography background.

f/something is the focal ratio, not the aperture, although in a camera when you set the aperture you get the focal ratio value on the display. Focal ratio = focal length/aperture. So when you bring the f. ratio up you're telling the lens to reduce the aperture. So the inscribed f/ratio on a lens is an indication of the widest aperture you can achieve with it.

On a scope this doesn't happen, the aperture and focal lengths are fixed making the focal ratio fixed as well. The only thing you need to consider focal ratio for is:

1) In astrophotography a lower f/ means more light with shorter exposures. This is not noticed visually.

2) Visually the lower the f/ (anything under 6) the more demanding it becomes on eyepieces. Cheaper ones will show aberrations to the edges.

3) The lower the focal ratio the more sensitive it is to collimation.

4) With very long focal length eyepieces you'll get a brighter sky background and may loose some of the light the scope collected. You want an exit pupil under 7mm to keep it smaller then the human eye diameter. Ideally under 5mm for more contrasty views. Exit pupil = [EP focal length] / [scope f/ratio]

In visual astronomy, what really matters is the aperture (lens/mirror diameter). The wider it is, the more light you get focused to your eye so you'll see fainter objects. Inevitable, when you have very wide apertures you need long scopes scopes as well. For example, a 16" (400mm) even at f/4.5 will be 1800mm tall, plus the base, so a small step leader is needed to peek trough when pointing at zenith.

[gedmac]

sorry cant comment on the 300p as i own a mere 200p,but if your interest is visual as opposed to imaging the best optics/pound are dobs.if you decide on a dob its now all about size and portability.the size from a 200p to a 250p and then on to a 300p is vastly different so the best way to decide is find a local astro group or visit a local shop.i use my scope in the back garden and wouldnt want to be lugging anything bigger in and out of the shed.remember what i was first told...........the best scope is a used scope......not one what sits unused.good luck;) btw the 200p is very sturdy