Eye piece height of 16 inch Dobsonian

[bluesilver]

Hi, I currently have a 10 inch Skywatcher goto Dobsonian and very happy with it.
I have only now just been thinking about upgrading to a larger one, but so far i have been unable to finding an answer on eyepiece heights when the unit is pointing straight up, basically i am looking for the eyepiece height when it is at the maximum height.

I was mainly interested to find out the heights of the Skywater 14 inch, 16 inch and 18 inch

I realise it is a basic question for now, but was hoping to find some information on this first.
If anyone has any information on this it would be greatly appreciated.
Thanks.
Peter.

[gaseous]

I can't give you an exact answer Peter, but I owned a 16" skywatcher dob for a while, and at about 6 feet tall, I definitely needed at least one step to reach the eyepiece when pointing straight up (or anything higher than about 60° if memory serves). Given the width of the base, this means you're kind of leaning in towards the scope, which your back will not thank you for over an extended period.

[raymo]

The 14" is 5ft 4" [162.5cm], the SW 16" IS 5FT 8" [172.72CM],and the SW 18" Stargate is 6ft 2" [189.23cm].
raymo

[skysurfer]

It depends on more factors.

* Focal length
* Mirror surface height above the ground

So eyepiece height is FL-Diameter/2+height above ground.

Mine (also 16") is 1800mm (f/4.5) and mirror is 20cm above the ground when pointer vertically, so it is 1800 - (400/2) + 200 = 1800mm = 1.80m.
And my eyes are 1860mm above ground (I am 1.96m) so I can almost observe objects near the zenith while standing, but for objects below 60º I have to bend or use an observing chair.

Shorter people have to use steps when observing near the zenith.
When that is a problem, get an f/4 16" Dob which has a 20cm shorter FL, but most eyepieces require a coma corrector.

[bluesilver]

Thanks for the replies, very good information there.
I am 6 feet tall, Sounds like a 14" or possibly a 16" might be a good size step up without being too much of a problem to use.
Appreciate the replies.
Thanks.

[gaseous]

The 16" is a pretty heavy beast - the base needs to be disassembled to move it, and the tube is pretty unwieldy. If it's going to be permanently set up then that's fine.

[bluesilver]

It won't be permanently setup, but will be left assembled if that makes sense.
I will be making a trolley or cart system so that i can leave it fully assembled and wheel it out and back in.
Where i am i have have no city lights or such, so it is a dark spot
It is not going to be transported to and from sites, so it is just a matter of wheeling it out maybe 10 meters or so.

[gaseous]

Sweet. If you're ever in Brisbane and want to buy an official Skywatcher Dob Trolley (used 3 times), let me know.....

[bluesilver]

Hi, just another question on these larger Dobsonians, and please let me know if i am heading off in the completely wrong track here.

If i were to say to go to a 16 Inch Skywater Dobsonian, will this give me even better and slighter larger images of the planets like Saturn, Jupiter?

Or am i better off looking for a different telescope for planet viewing?
Any information is appreciated.
Thanks.
Peter.

[gaseous]

Hi Peter,


your 10" dob has a focal length of 1200mm, and the 16" dob would be 1800mm, so you'd be getting a 50% increase in magnification for any chosen eyepiece. (say, 120x (10") vs 180x (16") with a 10mm eyepiece). The views would certainly be brighter with the larger light gathering capacity, but to be honest I don't think planetary viewing is the target audience for these large dobs - I certainly never really used my old 16" for that sort of thing - it tended to sometimes make the views of Saturn and Jupiter a bit too bright, and therefore lost some detail. Not to say it can't be done, but if planets are your thing then something with more focal length and a great deal less cumbersome might be more suitable. Your 10" with the right eyepieces and / or barlow is probably fine for planets, but if you're also going to be chasing DSO's, then a 16" would be a step in the right direction.

[bluesilver]

Appreciate the honest reply.
It is the kind of answer i am looking for.
I am kind of looking for both, Planets and also now just starting to look at DSO's, but only just starting to look for them.

So i am guessing that to do both, i really need two separate Telescopes?
I might start a new thread for this then as it is not really related to this one.

But thanks very much to all for the advice's given here,
It is appreciated.
Peter.