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Old 22-04-2019, 05:44 PM
bluesilver (Peter)
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Eye piece height of 16 inch Dobsonian

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.
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Old 22-04-2019, 06:49 PM
gaseous (Patrick)
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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.
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Old 22-04-2019, 07:17 PM
raymo
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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

Last edited by raymo; 22-04-2019 at 08:43 PM. Reason: more text
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Old 22-04-2019, 08:24 PM
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skysurfer
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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 60 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.
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Old 23-04-2019, 07:58 AM
bluesilver (Peter)
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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.
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Old 23-04-2019, 08:01 AM
gaseous (Patrick)
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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.
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Old 23-04-2019, 08:29 AM
bluesilver (Peter)
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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.
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Old 23-04-2019, 09:00 AM
gaseous (Patrick)
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Sweet. If you're ever in Brisbane and want to buy an official Skywatcher Dob Trolley (used 3 times), let me know.....
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Old 24-04-2019, 09:02 AM
bluesilver (Peter)
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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.
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Old 24-04-2019, 10:04 AM
gaseous (Patrick)
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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.
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Old 24-04-2019, 10:47 AM
bluesilver (Peter)
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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.
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