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Large Aperture Portable Dobs


DeepSkyMan

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Hi there, I’m currently in the throws of planning an observatory build for this year.  Now I hear you say, what has an observatory got to do with large aperture dobsonians... bear with me all will become clear.  My intention is to eventually set up my EdgeHD in the observatory as an imaging platform in Hyperstar mode, but I feel I still need to see those photons in their raw form, so at some point I would like to add a good quality large aperture Dob to my growing Astro ‘stable’.  Towards this end I have been reading up on products by a couple of vendors.

Initial thoughts were more along the typical ‘mass market’ commercial solutions, in particular the 14” Skywatcher Flextube, however portability is going to be important to me as this will be my preferred dark skies instrument, so whilst the convenience of the Flextube is definitely attractive, the weight and awkward handling characteristics of the base and rocker box got me to thinking along different lines.

Next up was Hubble Optics and their UL14, however the distance of the vendor from the U.K. and risk that that implies leaves me nervous to say the least, especially after reading some of the reviews available on the various forums.  Whilst I am quite happy to tackle setup gremlins which are a natural hazard in this hobby we love, some of the reviews I’ve read on the HO products imply shall we say a little bit too much overhead in this respect:-)

Ideally I would like a product that comes out of the box and functions according to specification once constructed and doesn’t require DIY alterations just to get it to function as advertised so this got me thinking about higher end solutions.  Being part of Europe (although Brexit seems to imply otherwise), that naturally got me thinking about Sumerian Optics.  I really like the look of the Canopus and Alkaid, however, the web-site whilst very glossy is a bit short on detail, hence the reason for this post.  Does anybody have the relevant break down weights for the Canopus and Alkaid components, both 12 and 16”?  How portable are they?  How easy to setup and use are they?  Eyepiece position doesn’t really bother me, I am, shall we say, little ‘height challenged’ and I typically  find myself on my portable steps anyway even working with my 8” Edge, so having to climb higher isn’t a deal breaker.  As to my travel capabilities I drive a large SUV and I’m hoping that this will more than do the job for a Sumerian, be it the 12 or 16”.

 

Kind Regards

Paul.

Edited by DeepSkyMan
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No experience with the named scope makers but I do have experience with truss dobs. Mine are classic but to me a must have is the ability to use 'wheel barrow handles". The favourite scope here is a 15" f4.8 truss dob which is left assembled.

I would make sure the optics are what they say they are as a good spec large dob can be super on the moon and planets- my 15" goes well over 700x on the moon in good seeing.Low obstruction, 22% or less is what I prefer but for sure under 25%.

Oh and make dang sure the mirror cell is a capable one IMHO...

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I'm sure you will find that information shortly, Paul. Meanwhile I'd like to comment on your approach a little bit to give you some third party perspective.

I believe that a 12" and even 16" Dobs aren't really "Large Aperture" Dobs. Thus, there is no truly appealing reason to hunt for a "Portable" design specifically unless the goal is the air travel as well, as a truss like those Sumerinas can be folded really compact to pass airlines restrictions easily. But that contradicts with your desire to have a mobile instrument which is ready to observe "out of the box". All trusses, especially "ultralights" will require you to tediously assemble it every time and then collimate it. They are flimsy mechanically and not well protected from elements. Thus you will surely need additional accessories to make a bare truss more tolerant to the field abuse and addon equipment support. Their design's primary goal is to collapse to a "carry-on or checked luggage" size. Thus there are a lot of engineering compromises and sacrifices for that goal.

Not sure why you are concerned about the weight and a split weight while planning to travel by a large SUV (maybe fuel efficiency?), but if you look at the weight, the assembled Alkaid12 is 16.5kg. My z12 is 38kg. But Alkaid's rocker and base are tiny compared to z12, so I can speculate that 90% of the Alkaid's weight is in the OTA (~15kg, surely it has a different composition, so that 15 kg is the rocker/base/mirrors boxes and struts separate, but you got the idea). My z12 OTA weight is 20 kg. So the hand carry difference is just 5 kg! z12 rocker and base module is around the same weight (18 kg) as well. So I would in a snap sacrifice the second trip to/from the car with that weight for the clear benefit of instant telescope assembly/take-down, which I'm enjoying  with my z12 solid OTA for over a decade already vs any same size "easy to setup" truss which will require many small pieces assembling in the field often in the dark. I'm just coming out of the car with the base in the hand and EPs pack on the back, finding the open level spot, drop it there, return to the car for the OTA, carry it in both hands (by comfortable wide spaced rope handles) to the site, drop it into the base, and immediately start observing. The solid OTA also means that your collimation will stay intact for a very long time, even after a rough rural road ride. I'm enjoying it all the night and in the morning just dropping back the OTA, then the base (already too tired to care about some truss disassembling). Ready to drive home or drop down the dark tent and take a nap (by the way, my dark tent is popup as well, no poles or stakes to fiddle with, just unzip, drop to the ground so it can unfold itself, throw-in the self-inflating pad, then sleeping bag, and you are cozy. A bit heavy, yes due to springs in all seams, not for backpacking, but it's ready to roll instantly). Very time efficient as well, as I don't have to plan arriving before dark to have time for setup in the day-light and can tear-down before dusk to hit the road before the traffic starts stacking up.

IMG_1273.jpg 
Above - my 2002 trunk, base on the left, OTA in the cradle on the right.
What "base bulk"? It's the trunk space divider! "Awkward carry"? Just remove the nonsense eyepieces holder on the side and it behaves as a briefcase in your right hand (base forward).

The SW Flextube is heavier than solid steel OTA by about 2 kilos for 12". It might be appealing for small cars, but with the SUV a full OTA or collapsible doesn't matter (for you it is). I'm driving small SUV (Subaru Forester). z12 was fitting perfectly in 2002 model with the front seat moved forward. In 2018 model even that is not needed. To make things even easier I built this ultimate solution for it (cradle above). So on a developed campground (paved) I'm simply removing the cradle as a drawer, mounting the base on top and rolling it to the observing spot (usually a huge open day-use parking lot empty at night) that's a single easy stroll (just don't forget the backpack with accessories). On a rural site it's not needed as I'm usually setting up right behind the car.

Edited by AlexK
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  • 1 year later...
On 27/01/2021 at 20:46, DeepSkyMan said:

Hi there, I’m currently in the throws of planning an observatory build for this year.  Now I hear you say, what has an observatory got to do with large aperture dobsonians... bear with me all will become clear.  My intention is to eventually set up my EdgeHD in the observatory as an imaging platform in Hyperstar mode, but I feel I still need to see those photons in their raw form, so at some point I would like to add a good quality large aperture Dob to my growing Astro ‘stable’.  Towards this end I have been reading up on products by a couple of vendors.

Initial thoughts were more along the typical ‘mass market’ commercial solutions, in particular the 14” Skywatcher Flextube, however portability is going to be important to me as this will be my preferred dark skies instrument, so whilst the convenience of the Flextube is definitely attractive, the weight and awkward handling characteristics of the base and rocker box got me to thinking along different lines.

Next up was Hubble Optics and their UL14, however the distance of the vendor from the U.K. and risk that that implies leaves me nervous to say the least, especially after reading some of the reviews available on the various forums.  Whilst I am quite happy to tackle setup gremlins which are a natural hazard in this hobby we love, some of the reviews I’ve read on the HO products imply shall we say a little bit too much overhead in this respect:-)

Ideally I would like a product that comes out of the box and functions according to specification once constructed and doesn’t require DIY alterations just to get it to function as advertised so this got me thinking about higher end solutions.  Being part of Europe (although Brexit seems to imply otherwise), that naturally got me thinking about Sumerian Optics.  I really like the look of the Canopus and Alkaid, however, the web-site whilst very glossy is a bit short on detail, hence the reason for this post.  Does anybody have the relevant break down weights for the Canopus and Alkaid components, both 12 and 16”?  How portable are they?  How easy to setup and use are they?  Eyepiece position doesn’t really bother me, I am, shall we say, little ‘height challenged’ and I typically  find myself on my portable steps anyway even working with my 8” Edge, so having to climb higher isn’t a deal breaker.  As to my travel capabilities I drive a large SUV and I’m hoping that this will more than do the job for a Sumerian, be it the 12 or 16”.

 

Kind Regards

Paul.

I don't know where you are in this project, but if you are still looking for a ready to use out of the box 16 inch, FLO has a GSO 16 inch truss available now.  Reviews of it have been very positive.

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55 minutes ago, Mike Q said:

I don't know where you are in this project, but if you are still looking for a ready to use out of the box 16 inch, FLO has a GSO 16 inch truss available now.  Reviews of it have been very positive.

I've looked through one. Great scope but I wouldn't call it portable!

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42 minutes ago, Mr Spock said:

I've looked through one. Great scope but I wouldn't call it portable!

Build or buy a dob cart, put it on and leave it there.  

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