Some questions about telescopes

[Tzitzis]

Also got it! Thanks mate! Best magnification= reduced viewing area. 

John, I will have to move my dob (if I buy one) consantly. Athens sucks for stargazing, and if I want to stargaze in Athens I will have to move it up to the rooftop. If I go to a rural location, well I will have to transport it too.

Thanks a lot guys! All of you!

[Dom1961]

As for the Dob V EQ argument, I was planning on getting a EQ before as I thought the same thing as you, but now I have a dob I actually dont find it hard to keep the object in the eyepiece.

[ollypenrice]

The faster a scope's optics are, the less time it will take to take a good photo/image through it. Here's an example: If you have a scope that is F/10, and let's say it  takes 10 seconds to take a photo/image through it, if you have a scope with F/4 optics, it will take 4 seconds to get the same image through it. This is very useful if you have the scope mounted on a mount that doesn't track very accurately. The less time it takes, the less the scope will drift off target during the exposure.

However, the faster scope will also give you lower magnification with a given eyepiece:

Exposure times go as the square of the f ratio so, using minutes or seconds, F4 (4x4) = 16 minutes while F10 (10x10) = 100 minutes. The difference is pretty extreme but it matters little for a visual observer.

I would always go for a Dob for easy transportation and setup. Equatorial mounts introduce the need for counterweights, entangling tripods and polar alignment.

Olly

[Tzitzis]

Well it's the moving part I'm worried

[Dom1961]

Im 14 years old and Im quite small and not very strong but I manage to move my 8" Dob to my back garden from my room quite easily, they seperate into the OTA and the base for transportation

[Tzitzis]

I will have to move it upstairs in the rooftop .No elevator. And I will have to move it with car also.

[rwilkey]

But Skywatcher has f/5. It's "quicker" than the Spaceprobe.

By the way, what's up with that? What does quicker mean for a telescope. I don't get it.

It means it is a 'faster' scope and more rich-field, in my opnion an f/6 scope is better than f/5.  F/5 can be a bit demanding on eyepieces.  Also, I would say forget the Barlow to start with, see how you get on with the supplied eyepieces, telescopes are not about magnification, although that is a part of it.  Also, don't get a Moon filter unless you feel you really need one, many people manage without a Moon filter, so you may find this a waste of money.

[Tzitzis]

Didn't know that. Well thanks!

[happy-kat]

My take is simply put the light travels less distance from the receiving lens/mirror to your eye piece the faster the telescope.

[Matt Scunthorpe]

If your worried about moving it around etc, then its not even a question, you'll be better off with a dob. If you're going up to the rooftop with an EQ mount, you'll be doing It in trips, legs and weights, mount, scope, then EPs etc. A lot of stuff to leave on your rooftop with no supervision, and then you'll be doing it in the reverse order at the end of the session.

If your going in the car with it, then its not really much of an issue as you'll probably set up next to the car.

Matt.

[Tzitzis]

Suppose I get a dob... 

How will I "follow" the objects in the night sky without polar allignment and slow-mo knobs?

[Matt Scunthorpe]

You use your hands to nudge the scope in the direction that its going.

Matt.

[Tzitzis]

But I won't be able to follow the object so good, it will keep going out of view and I will be trying to find again. At least that's what I think.

But since we talk about dobs... I am interested in viewing Nebulas and clusters and galaxies. I want I scope I can watch many of these Messier objects. Will an XT4.5 do it for me?

[Tzitzis]

http://www.astroshop.eu/skywatcher-dobson-telescope-n-150-1200-skyliner-classic-dob/p,15559#tab_bar_1_select

Someting like that.

[John]

You need as much aperture as you gan get for deep sky objects. The 6 inch / 150mm will therefore be quite a lot better than a 4.5 inch / 114mm because it captures a lot more light.

I understand your concerns about tracking objects at high magnifications. It's entirely possible with dobsonians with just a little practice. I've often used 300x or more with my 12" dob. The other thing I've found with dobs (I've owned a number of equatorial and fork mounted scopes too) is that the simple mount design dampens vibrations very well.

[Matt Scunthorpe]

You will be fine once you get used to it. The 8" skywatcher dob is the best selling telescope for a reason, and there are 100s of people on this forum that use dobs and will say how easy it is once you get used too it.

The other links that you have posted will be the same, none of those scopes will follow the object, so you will have to keep getting it back into centre of view, albeit you will only need to turn the RA axis to keep it in view, but the only way you'll get one that actually follows the object will need a motor or a goto kind of system.

http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-eq-5-pro-goto.html

Something such as this, another possibility is just the EQ5 motors. I could not find a link to this, but I have the RA motor on my EQ5 and it works well.

Matt.

[Tzitzis]

You know something, you are right. I mean I was thinking about how difficult pollar allignment is, well at first. Also I think that you can't change your position after alligning and that's a drawback.

I've given it some thought, and that SkyWatcher dob is "budget alligned" so unless anyone else has to suggest anything else, I'm going to lock on the dob and start raising money furiously.

[Matt Scunthorpe]

Its a good choice that will see you well while you get started. I myself am actually going to get a dob shortly just for the setup time (or lack of it), as setting up the mount and everything else puts me off going out.

Matt.