Big Dobs - are their days numbered?

[Richard N]

In the last month our Society has been unable to find homes for two 16 inch Dobs. Both were offered free. Both "required attention" making them something of a project. One was given back to its donor and sadly the other was scrapped (mirror retained). Both had homemade mirrors of unknown quality. I did get to look through the one that was scrapped. It looked great on the Moon. No doubt some will say this is sacriledge but in a situation where a scope can't be left where is was being stored, no-one could fit it in their car and ultimately, no-one was interested, there wasn't any other option. Big visual Dobs seems to be the preserve of a very few specialists these days.

[AstroKeith]

I believe the key is ' homemade mirrors of unknown quality'.

Although the mirror is a major cost item, building or fixing up the rest of the scope is a major investment in both time and money. You want to start with a mirror set that is known at least, and for me - a good one.

[Xilman]

Is the (relatively) intact one still available? I'm pretty sure that if advertised here on SGL it would quickly find a good home.  I may even be interested in it myself.

[niallk]

7 hours ago, Richard N said:

no-one could fit it in their car and ultimately, no-one was interested, there wasn't any other option

Shame - a well designed dob that breaks down for convenient transport is key, unless one is lucky enough to not need to escape light pollution!

[John]

I think that relatively few astronomers have the location and / or energy levels to make the most of a big aperture dobsonian. I have certainly considered 14, 16 and even 20 inch dobs over the past couple of decades but boring practicalities combined to make me realise that I would simply not be able to use such a scope often at all - maybe just a couple of times a year ?

My astro society has an 18 inch NGT newtonian at it's observatory site just a few miles from me. The scope needs some TLC and in many ways does not fit in with the way society members interests are going so I guess it will be disposed of at some point and I'd be surprised if there was much interest in it, despite the fact that the NGT 18's were high quality scopes and very attractive when they were launched back in the 1990's

Here I am using the scope a while back. The GOTO does not work so it's manual finding and that is enough to discourage some (not an idiot like me though 🙄)

 

 

Edited May 19 by John

[dweller25]

I always found the idea of a big Dob in the 16” range appealing, but then practical thoughts came into my head and I never got past 10”

Now I have some nice APO refractors, but neither put up the views that the 10” Dob showed.

But just imagine what the 16” would do 🤔……….

Edited May 19 by dweller25

[AstroKeith]

The 'Ultra Compact' layout for Dobsonians, exploited by Obsession results in very transportable scopes.

My own 18", self built, easily fits in the boot of my Mustang.

[tomato]

22 minutes ago, AstroKeith said:

The 'Ultra Compact' layout for Dobsonians, exploited by Obsession results in very transportable scopes.

My own 18", self built, easily fits in the boot of my Mustang.

That’s why I’m converting my humongous Skywatcher 16” Flextube to that type of scope, but I have to choose my words carefully.😉

[rl]

About a year ago I offered -free- three Dob mirrors on this site, collection only.  All three would have made a good Dob project. The only one to go was a 14" f/5.7 by AE optics. One is a 18.5" by Oldham Optics which I thought would have been snapped up but the relatively long focal length probably put people off; you needed a ladder to reach the eyepiece when pointed at the zenith. I did make a scope with this mirror and it was indeed optically wonderful, but the operational risk to life and limb made it hard to justify its place in the garage...it cured me of aperture fever. I'm down to 14" now and I may sell that one in the near future. 

Dobs have always been the classic DIY scope, and DIY scopes generally seem to be on the wane. Looking at the quality and price of some of the imports you can see why.

I think more and more people are primarily interested in photography now, the visual attraction of full-colour high-res pictures which you can get published will for many outweigh the more arcane satisfaction of star-hopping from one fuzzy blob to the next. Not a judgment; I do both, and neither particularly well!

The UK weather probably holds a veto on many people's ambitions now. It's easier (and less controversial) to justify keeping something that breaks down into small pieces easily and unobtrusively stored than have a massive scope lying idle for weeks on end in the house. 

[maw lod qan]

I find this very interesting. 

As time goes on, how many young people will really have the dedication to have a telescope like these mentioned to observe, when they can click on the internet to see an image.

Will they have that, "I'm really looking at this with my own eyes" thinking?

[Stu]

I guess if you think what the little Seestar is capable of now, fast forward five years and….. 😱

I have a 16” dob in the garage but it hasn’t been used for a while…..

[PeterStudz]

1 hour ago, maw lod qan said:

I find this very interesting. 

As time goes on, how many young people will really have the dedication to have a telescope like these mentioned to observe, when they can click on the internet to see an image.

Will they have that, "I'm really looking at this with my own eyes" thinking?

My daughter (she is 12, almost 13) certain does want that “I’m really looking at this with my own eyes”. And my experience with other kids is that they often do too. 

I think the issue here is often light pollution. Eg when we go on holiday to a place which just happens to have a dark sky the first thing (and it literally is) when we get there that she says is “can we go and see the Milky Way?”. This despite having seen it all before and having seen it numerous times on the internet & in books. 

At home we are limited to the planets (which actually go down really well) and a few bright DSO. With this limitation enthusiasm can quickly dwindle. And a really a massive Dob in a light polluted sky isn’t really going to help. 

Edited May 20 by PeterStudz

[PeterStudz]

6 minutes ago, Stu said:

I guess if you think what he little Seestar is capable of now, fast forward five years and….. 😱

 

Yes, it kind of reminds me of the beginning of the smartphone era. 

[Xilman]

Back in the day I had an 18" Dob from Beacon Hill Telescopes. Bad spherical aberration but I didn't much care because I wanted a light bucket for VS observing. It sat in a trolley and lived in a small converted shed on my back yard. Setting up was a five minute or less task. Did very good work from a light polluted site and was eventually sold to a group at RAL who wanted to build a lidar system.

I now have a 10" Dob here in the UK. I would like a large Dob (45-80cm say) over in La Palma but I need to get the rest of the kit out there in better shape first.

 

[Xilman]

27 minutes ago, PeterStudz said:

At home we are limited to the planets (which actually go down really well) and a few bright DSO. With this limitation enthusiasm can quickly dwindle. And a really a massive Dob in a light polluted sky isn’t really going to help. 

I am going to go out on a limb here and make a possibly unpopular comment which may get people mad at me.

 

Big Dobsonians can make very good imaging telescopes.

 

As an existence proof, I give Martin Lewis who uses an 18" Dob from a suburban back yard near St. Albans. He takes superb images of planets, many of which have won awards.. He's imaged the surface of Venus, for instance, through narrow band IR filters. He has picked up the brightest  ring of Uranus. He resolves details on the surface of the Galillean satelites of Jupiter. Any search engine will turn up examples of his work.

Martin uses an equatorial platform and a video camera. I claim that for some work the equatorial platform is not essential, albeit desirable, but the high frame rate camera is required to take decent images. Yes, the object of interest drifts across the FOV but a fair number of frames can be taken before the OTA needs to be moved in position for another set of subs.

Moral: don't write off anything until you have tried it for yourself, especially if others have succeeded.

 

[paulastro]

'Smart Telescopes are only the start of it.  This (below) being another development.

Its been the case for a long time that large dobs (16 to 20inch plus) are a very hard sell in the used market, and this applies even to Obsessions which only fetch a fraction of their new price.  I've had this conversation many times with big dob owners and users at Kelling.

[saac]

I don't think their days are numbered rather they are as they have always been more specialist rather than generalist telescope.  Apertures of 16 inch and above, no matter how well designed, will always require a certain amount of commitment due to handling and storage requirements.  They will always have their appeal to those who can.  

Jim 

Edited May 20 by saac

[PeterStudz]

2 hours ago, paulastro said:

'Smart Telescopes are only the start of it.  This (below) being another development.

Its been the case for a long time that large dobs (16 to 20inch plus) are a very hard sell in the used market, and this applies even to Obsessions which only fetch a fraction of their new price.  I've had this conversation many times with big dob owners and users at Kelling.

Yes, I’ve seen that. Interestingly, when I started out and first heard of EEVA I naively imagined that it was similar to this  - or more like a device to replace an eyepiece that would enhance the view. And enhance it in such a way that it would be as if you were observing in Bortle 1. All live too or close to it, similar to night vision I guess. After all, in this day and age how hard can it be!

The above device looks similar to an app on my iPhone - AstroShader - that auto aligns and does live-stacking to give a close to live preview. Just that here it’s all in an eyepiece replacement, hopefully far more convenient and with a better camera. 

[bingevader]

2 hours ago, saac said:

I don't think their days are numbered rather they are as they have always been more specialist rather than generalist telescope.  Apertures of 16 inch and above, no matter how well designed, will always require a certain amount of commitment due to handling and storage requirements.  They will always have their appeal to those who can.

Indeed. They have always been a bit of a niche market.

As Xilman said, not sure why they weren't offered on here.

I'd never say no to a free 'scope for school.

Not sure how we'd have got it down from Macclesfield!

 

[Xilman]

8 minutes ago, bingevader said:

Not sure how we'd have got it down from Macclesfield!

I note the smiling face, but do you really have that little imagination?  Renting a van is really not very expensive, especially in comparison with the cost of a fair-sized telescope.

[John]

Perhaps folks want everything to be easy today ?

"plug and play" "grab and go" "point and click"  - big dobs are none of these. They take commitment, effort and the development of skills and experience. The rewards can be great but they have to be earned and even then, apart maybe from a few sketches and notes, the results are only held in peoples memories. No pictures so it didn't happen, maybe ?

Maybe big dobs don't fit in so well with the room that people have in their lives for hobbies these days and the role that a hobby plays for them ?

 

 

 

 

 

 

[IB20]

I’d love to look through a massive dob but have very little, if any, interest in owning one. For me visual astronomy is about relaxation and de-stressing, I don’t think works so well with any DIY element, difficult handling of extremely large scopes or even having to observe on a ladder. 
Conditions play a part too, perhaps if I lived Nevada or similar I’d be more inclined to want a big dob.

[Alan White]

11 minutes ago, IB20 said:

I’d love to look through a massive dob but have very little, if any, interest in owning one. For me visual astronomy is about relaxation and de-stressing, I don’t think works so well with any DIY element, difficult handling of extremely large scopes or even having to observe on a ladder. 
Conditions play a part too, perhaps if I lived Nevada or similar I’d be more inclined to want a big dob.

This mirrors my own thoughts

[PeterStudz]

24 minutes ago, IB20 said:

I’d love to look through a massive dob but have very little, if any, interest in owning one. For me visual astronomy is about relaxation and de-stressing, I don’t think works so well with any DIY element, difficult handling of extremely large scopes or even having to observe on a ladder. 
Conditions play a part too, perhaps if I lived Nevada or similar I’d be more inclined to want a big dob.

I agree with most of this apart from the DIY bit. Everyone is different but when I made the base for my Dob, took the OTA apart and put it back together again, made an EQ platform… I found it extremely relaxing. All made outdoors with simple tools, eg all hand sawn - so something anyone can do. Most was done during the lockdowns and as I was working outdoors I needed fine weather - I’d actually feel relatively down if it was raining and I had to find something else to do!

Mind, I should add that I hate doing household DIY, much to the frustration of my wife!

Edited May 20 by PeterStudz

[saac]

1 hour ago, IB20 said:

 For me visual astronomy is about relaxation and de-stressing,

Not mutually exclusive with ownership of a big dob. The phrase "always paddle your own canoe" comes to mind   One of the great things about this "hobby" is it offers enough variety to challenge, stretch, frustrate in equal measure to personal preferences while keeping us all happy.  

Jim 

Edited May 20 by saac