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Dobsonian Telescopes


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Hello Everyone

Hope you're enjoying your weekend.

I think I've narrowed my first telescope purchase to a 6" Mak-Cass. 

But I keep thinking about the 8" or 10" Dobsonian scopes as they are actually less expensive than my potential 6" purchase and let in more light at the same time.

The thing that concerns me is what I would consider an akward viewing posture. I'm 6'1" tall and I'm trying to think how I would be able to use that scope without being too uncomfortable. Do they make special eye pieces to accommodate those concerns?

If sure like to hear from anybody who uses a large Dobsonian scope.

Thanks

 

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Hi and welcome to SGL. My first scope was an 8” Dob which I still have and use whenever skies permit. I f you want to stand when viewing then you could use a water butt base to raise the height or alternatively use a seat for more comfortable viewing. I once had a 127 Mak but I sold it because it was too prone to dew problems which has never been a problem with the Dob.

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The best thing to do while using an 8-10" dob is to observe whilst seated. I find that an adjustable drummers stool (the type that spin up and down) is the perfect height for observations at all altitudes. I'm 5'10" so you might find it a little bit more difficult if trying to observe something right down by the horizon but generally that isn't something you do as the atmosphere degrades the image significantly in that scenario. 

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I find my 8" F/6 dobsonian really comfortable to use in seated position. I'm also about 6'1" - but that does not make a difference when seated if you get observing chair that is adjustable.

10" F/4.7 has same focal length and same tube length (give or take) as 8" F/6 - so using it would be the same.

Even using 12" (1500mm FL) is doable in seated position if you have height adjustable chair.

 

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I'm a 6ft 1 inch DOB user. I have a 8" f 6 DOB and have never experienced any discomfort using it.

The focuser sits at an angle of 45 degrees from vertical (or horizontal!) and is presented at a very comfortable angle to the eye. Of course it depends on the seat height. Too low and it can be a neck crane at the zenith, and too low turns it into a crouch near the horizon. An adjustable height seat is ideal, think drummer's stool.

No special eyepiece needed.

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I had quite a big dob. I bought an adjustable chair like this one 

https://www.amazon.co.uk/Leifheit-Multi-Seat-Niveau-White/dp/B0000DH7KA/ref=sr_1_2?dchild=1&keywords=ironing+chair&qid=1622381321&sr=8-2

I've seen them called ironing chairs but I found it very convenient observing at the eyepiece.

The only problem I had with the dob was that the base was very heavy and I had to move it in and out of the shed each time. Moving the base first and then the scope. 

Steve

 

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I am 6ft 1inch and I own a SW 200P Dob. I have no issues at all with viewing; I mostly do sitting viewing but standing is not an issue either for brief periods. You may want to consider a RACI since you can avoid awkward position trying to find your targets (I never used the straight finder in my telescope). I have seen other recommending to put it on a water butt base but I am not sure I would trust mine on it, but it would allow you to view standing.

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I got an 8" Dob last August. I'm 6'5" and can report so far no issues (apart from operator error 😄)

Get yourself an adjustable chair/ stool and a water butt stand and you've covered pretty much all height related viewing situations.

20210222_200425.thumb.jpg.699636f5de7aa5023a2e01c79f209543.jpg

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1 hour ago, Goldfinger said:

Hello Everyone

Hope you're enjoying your weekend.

I think I've narrowed my first telescope purchase to a 6" Mak-Cass. 

But I keep thinking about the 8" or 10" Dobsonian scopes as they are actually less expensive than my potential 6" purchase and let in more light at the same time.

The thing that concerns me is what I would consider an akward viewing posture. I'm 6'1" tall and I'm trying to think how I would be able to use that scope without being too uncomfortable. Do they make special eye pieces to accommodate those concerns?

If sure like to hear from anybody who uses a large Dobsonian scope.

Thanks

 

Sounding dangerously Yoda like, I'd say 'Raise the dob., lower the observer, one or the other, or both, whatever works .

I have a heritage 150 dob, which has a low tabletop base , so have built a rough little sturdy stand to raise it off the (usually wet) grass, and an adjustable height observing chair ,you can see both here

What  do you hope to observe with your 'scope ? That would be an important factor to me in a decision between dob and mak .

Heather

 

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Posted (edited)

I'm 6 foot tall. I like to stand when observing. This is my 12 inch dobsonian. The base was custom made to suit my eye height. This has been the best scope I've owned in the 35+ years I've been in this hobby (I've owned many !). I've seen more with it than with any other scope that I own. I use very wide angle eyepieces at low, medium and high magnifications which make tracking just that little bit easier. What suits me might not suit you though so continue to ask questions and think about the various options available :smile:

12dobwaiting.JPG.74773af3ea9624afeecc9ddbe83e3a14.JPG

Edited by John
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Posted (edited)
11 minutes ago, Tiny Clanger said:

Sounding dangerously Yoda like, I'd say 'Raise the dob., lower the observer, one or the other, or both, whatever works .

I have a heritage 150 dob, which has a low tabletop base , so have built a rough little sturdy stand to raise it off the (usually wet) grass, and an adjustable height observing chair ,you can see both here

What  do you hope to observe with your 'scope ? That would be an important factor to me in a decision between dob and mak .

Heather

 

Surely Yoda would levitate the Dob until the eye piece was in the perfect position for the observers eye!!!!!!!! 😄

Edited by reddoss
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30 minutes ago, Tiny Clanger said:

Sounding dangerously Yoda like, I'd say 'Raise the dob., lower the observer, one or the other, or both, whatever works .

I have a heritage 150 dob, which has a low tabletop base , so have built a rough little sturdy stand to raise it off the (usually wet) grass, and an adjustable height observing chair ,you can see both here

What  do you hope to observe with your 'scope ? That would be an important factor to me in a decision between dob and mak .

Heather

 

To tell you the truth, I simply don't know yet. This would be my first serious telescope. The reason I'm purchasing one is because I simply can't sleep at night and I'm usually up by 3:00 am. Rather than toss and turn for the rest of the night, I'll just set up the scope and see what's up in the sky. I'll just point it wherever until I find something interesting then try to identify it using the the Stellarium app.

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I've not had my 250mm Dob long but already it's too low even seated. My main observing area hasn't been used yet but that has 3 50mm paving slabs on it. I'm hoping that will help.

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28 minutes ago, Goldfinger said:

Does anyone have opinions on the collapsible Dobsonian scopes like this one? Being a newbie not quite sure what to think of them.

https://www.bhphotovideo.com/c/product/735539-REG/Sky_Watcher_S11720_10_Dobsonian_Telescope.html

 

 

The main advantage of the collapsible dob is if you have a storage space in which the collapsible dob will fit but the solid tube won't. Similarly it may be possible that you have a vehicle into which you can fit the collapsed dob on its base rather than putting the OTA and base in separately. 

The advantage of the solid tube version is that it is actually lighter (and so easier to carry) than the collapsible version and will probably hold collimation better. 

Personally, at 10" I wouldn't even consider the collapsible version. 

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Thanks for all the replies. You've been a terrific help to the newbiest of all newbies. Seriously...I'm a total newcomer to this hobby.

I have a question about lenses. Are lenses of the same size interchangeable? I notice there's different brands of lenses and filters and a lot of them are 1.25" in diameter.  Will they all fit any telescope that requires 1.25" lenses?

Or do I have a watch for specific lenses for special brands of telescopes?

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Posted (edited)

Many scopes can take either 1.25 inch or 2 inch eyepieces.

The larger size are used for low power / wide angle views. Most medium to high power eyepieces are in the 1.25 inch format and an adapter is provided with the scope to enable those to be used.

Generally, any brand of eyepiece can be used in any brand of scope. Depending on the specs of the scope, some eyepieces work a bit better than others.

 

Edited by John
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Posted (edited)

My advice is that an adjustable chair improves comfort, and therefore the observing experience, in any small to medium size dobson. That's for dobsons with focal length between about 1 and 2m. After that, a ladder is generally needed.

The uncomfortable alternative is that you lie on your knees and / or bend your back and neck to reach the right altitude..

With my 12" F6, I use a three steps ladder: 1st step is when standing when the telescope points at the zenith, whereas the other two steps are for sitting when the telescope points at low altitudes. In between, I stand. 

With my 16" F4, I stand when pointing at high altitudes and sit on the three steps ladder otherwise.

All of this is going to change after completing my adjustable chair which is based on a Catsperch chair style. With this I will observe sitting all the time.

If you have some basic skills, you can build your own. Look up: "Denver observing chair". Berlebach also makes some adjustable chairs, but they seem quite flexible to me... There are also some metal chairs like the Starbound, and its US and EU clones. Some observers use chairs for ironing clothes.. 

There is a quite large range of options.

Edited by Piero
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I would:

- get a decent collimation tool (Cheshire/sight tube is fine).

- an atlas to get acquainted with the constellations and location of the bight DSOs (e.g.  Messier objects).

- consider 3 eyepieces with focal lengths of 24/25mm, 10mm, and 5/6mm assuming the 10" you are considering is something like F4.7 . The 25mm which comes with the telescope works quite well.

- skip filters for now.

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16 hours ago, Goldfinger said:

I'll just set up the scope and see what's up in the sky. I'll just point it wherever until I find something interesting then try to identify it using the the Stellarium app.

A Dobsonian sounds perfect for this purpose. It's more of an all rounder compared to the Mak which is mainly considered a planetary lunar scope, and the Dob has a simple Alt/az (up down left right) mount which is perfect for just plonking down and having a look around.

Don't worry about height, my smallest Dob stands about 9" tall! As said you can raise the scope up or lower your self down with an observing chair : )   

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Posted (edited)
18 hours ago, Goldfinger said:

...., I'll just set up the scope and see what's up in the sky. I'll just point it wherever until I find something interesting then try to identify it using the the Stellarium app.

To be honest, you might get more out of the scope / observing with a little planning and having some targets / locations in mind when you star using the scope.

Telescopes present a surprisingly small "window" of the sky in the eyepiece even at low magnifications. Apart from seeing quite a few more stars, you might not find anything more interesting to observe by just scanning around.

Binoculars are probably better for that.

 

 

 

Edited by John
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4 hours ago, Chris said:

A Dobsonian sounds perfect for this purpose. It's more of an all rounder compared to the Mak which is mainly considered a planetary lunar scope, and the Dob has a simple Alt/az (up down left right) mount which is perfect for just plonking down and having a look around.

Don't worry about height, my smallest Dob stands about 9" tall! As said you can raise the scope up or lower your self down with an observing chair : )   

9" tall? I can't imagine seeing much with that.😉

I like the 10 inch Dobsonian for two reasons. Price and aperture. I live downtown in a major light polluted city. I hope the larger diameter aperture might overcome some of that.

If I get really discouraged I can always sell it. 

As far as purchasing an adjustable chair for height, I'll just use some square seat cushions with a chair for the time being. 

 

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2 hours ago, John said:

To be honest, you might get more out of the scope / observing with a little planning and having some targets / locations in mind when you star using the scope.

Telescopes present a surprisingly small "window" of the sky in the eyepiece even at low magnifications. Apart from seeing quite a few more stars, you might not find anything more interesting to observe by just scanning around.

Binoculars are probably better for that.

 

 

 

That's a good point and that will come later. I've never owned a telescope before..much less one this big. I need to spend some time getting familiar with it and have no idea how long that might take.

After that, I could form a plan depending on what and where everything is located using my Stellarium app. I'd love to see if I can find the planets.

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