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When scopes start to get big.....

Moonshane

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Moonshane

Moonshane

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I thought I'd add this thread as I have taken the (not so great) photos for another thread and thought others might want to see them. I often see threads where people want to get a bigger and bigger scope and I was the same until I got my 16" dob. For me this is the ideal combination of large aperture and reasonably small size for such aperture.

Whilst I truly enjoy this scope and hope never to part with it, there's a surprising difference between a 12" and a 16" scope. Some people may not be aware of this jump in size, hence the thread, almost as a warning.

I currently have a 16" f4 and a 12" f4 (both Orion Optics) and therefore took the opportunity to compare the two side by side. The 16" is the one on the right :grin:

In comparison the 12" looks very small and is a lot more manageable and pretty much a grab and go. The 16" takes a little more effort but is worth it in the longer good evenings (remember those?). Hope this is useful to those considering larger aperture.

Also bear in mind that the Skywatcher 16" base is about 300mm in diameter more than my base which may be a factor.

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Naemeth

Naemeth

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no worries at all. and I agree they do often tend to make them look smaller online but it's hard to get scale with no comparison. here's the 16" when I first got the tube and mirrors next to a 6" f5

index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=37819

The scary thing about that is that the 6" will be slightly bigger than my scope, and my scope can pack itself away! Imagine that next to the 16"!

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John

John

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Useful comparison pics Shane :smiley:

The scopes pictured are the most compact for their aperture class you can get I reckon. The Widescreen Centre in London used to have (maybe still does ?) in their shop an Orion Optics 16" newtonian on an equatorial mount. It seemed to tower over everything in the shop and I can recall walking underneath the tube to get to the till !

The largest scope I've ever looked through was a 20" David Lukehurst dob. It was designed to be as compact as possible but still seemed a massive structure to me.

Amazing views though :shocked:

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Naemeth

Naemeth

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I am considering truss version to be honest to make it more easily transported. I can just get the OTA in my cheapie small hatchback (Daewoo Lanos) but it's a struggle to get the base in.

I'd say go for it, it will save on the weight at the very least. I think there is an important reason as to why pretty much all very large dobs are truss.

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Moonshane

Moonshane

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Useful comparison pics Shane :smiley:

The scopes pictured are the most compact for their aperture class you can get I reckon. The Widescreen Centre in London used to have (maybe still does ?) in their shop an Orion Optics 16" newtonian on an equatorial mount. It seemed to tower over everything in the shop and I can recall walking underneath the tube to get to the till !

The largest scope I've ever looked through was a 20" David Lukehurst dob. It was designed to be as compact as possible but still seemed a massive structure to me.

Amazing views though :shocked:

blimey, a 16" newt on an EQ mount - was it an EQ28? :grin: 16" f4 is nothing....(28" f2.7)

829-1.jpg

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Moonshane

Moonshane

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I'd say go for it, it will save on the weight at the very least. I think there is an important reason as to why pretty much all very large dobs are truss.

it will actually weigh quite a bit more I should think, albeit in easier chunks.

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John

John

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How will it weigh more?

Truss designs do seem to weigh a bit more than the solid tube versions. Also the Orion Optics newts are pretty light for their aperture. My 12" F/5.3 tube weighs around the same as a Skywatcher 10" F/4.7 optical tube.

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Naemeth

Naemeth

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F/2.7 :shocked:

That would be "coma city" without a Paracorr I reckon !

Google Comascope :D

Truss designs do seem to weigh a bit more than the solid tube versions. Also the Orion Optics newts are pretty light for their aperture. My 12" F/5.3 tube weighs around the same as a Skywatcher 10" F/4.7 optical tube.

It seems odd, but you probably need a lot of the truss tubes to support the weight of the secondary and the focuser. Mind you, it splits into two parts so would be easier to store and transport.

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crashtestdummy

crashtestdummy

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ive pretty much talked myself out of a mainstream 16" dob mainly due to the eyepiece heing at zenith being way above my 5'7" frame but my ultimate aim is the luckhurst 22" f3.6 that he has pictured on his website but tbh i would settle for the 18" 3.9 which would be more managable but 20"+ is the aim.i did actually plan on one of the orion optics solid tubes but obviosuly their customer service has put me off any future dealings.i was actually surprised how small my 300p was compared to how big i thought it would be but above that size they do seem to get huge and heavy fast!

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barkis

barkis

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A 16" versus 12" . A scope large in physical size, and ease of use has to be a factor, and seriously considered when contemplating purchase.

Storage facility too is to be considered.

One other decision making ingredient is the light gathering property of these mirrors.

16" area = 201 square inches, and the 12" has 113 square inches.

I would love to own a 20" Dob. having experienced observing through one at Kelling. Mind blowing. I'm still dreaming though :grin: .

Aperture is king, no doubt about it, but tempered with ones ability to manage the size you are considering, and probably transportation to dark sites

to draw out it's full potential.

Ron.

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LukeSkywatcher

LukeSkywatcher

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I am so glad that i have limited mobility or else my aperture fever would be so much worse. I am over the Moon with my Celestron 8SE, but to be honest if i invested time and money and had an Obsy built in my garden i would have a 14-16" scope of some kind housed there all year round.

Size really does not matter in astronomy, once you enjoy how and what you do with what you have.

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swamp thing

swamp thing

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Other factors with large dobs is getting through doorways, I'm currently building a 20" f/4 using the obsession blueprints in the KB book. This WILL NOT FIT through your standard 2'6" doorways. I will make the necessary alterations to the design so it does, but if ordering from a manufacturer make sure you measure everything twice. You don't really wanna be doing structural alterations to your house when it arrives.

Turning a big 20" mirror box on its side is not a viable option when you wana get the scope out.

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Mike73

Mike73

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I think the problem is sometimes that these scopes don't actually look that big on a website...

Eg: http://www.sumeriano...oducts/canopus/

I think a better example would be Skywatcher, go onto any retailers website and a 12" looks the same size as a 16" but in reality the size and bulk difference between those scopes are huge! Maybe retailers should put something in there images like a steel rule which showed the scale of each dob alot better?

Lots of very good points in this thread though for anyone considering a big dob, size isnt everything (but it certainly helps! :evil: ).

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