Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_solar_25.thumb.jpg.f1d5d01d306644f613efd90ef96b314c.jpg

Recommended Posts

Posted (edited)

As some of you know, I postponed the purchase of a Dobson for a few good years. Now that things in life are a bit more stable, I am in the market for this Dobson. 

It will take a bit before I press the button, as I still need to understand a few things about dobsonians. 

I've been contemplating a classic truss 12"-12.5" f5.5-6 for a while, as this would offer me a trade-off among portability, focal length, power, DSO, planetary, no coma corrector, and standup observing. 

Mirror and mount are equally important to me. I haven't yet decided, but I'm leaning towards an Astrosystems or Teeter 12.5" f5.5-6.

Yes, customs and shipping won't be cheap. It's a telescope to last though.

Any thought is welcome of course.

Piero

Edited by Piero
  • Like 1

Share this post


Link to post
Share on other sites

Your "wish list" seems very similar to mine Piero :icon_biggrin:

Although it has a solid tube, my Orion Optics based 12 inch F/5.3 does it for me. I've read good things about the Astrosystems and Teeter ones but I've not had the pleasure of actually seeing or using one.

Ultimately the UK seeing conditions can mean that a great 12 inch mirror can't always fully deliver it's potential so smaller aperture scopes like refractors can get surprisingly close to the planetary performance at times. On the deep sky though, no contest.

I'll look forward to following your progress towards dob ownership :icon_biggrin:

 

 

 

 

  • Like 3

Share this post


Link to post
Share on other sites
Posted (edited)

@bingevader  mm.. I'm not a great fan of ultra-light "naked" dobsons. Dobsons like Sumerian have portability in mind. Said this, from my standpoint sturdiness and ultra-portable do not go well together. To make it short, my main concern about ultra portable dobsons are collimation holding, thermal issues + dew formation with the primary mirror as this is (in my opinion) too exposed, particularly considering the UK climate.

@John  :) The OOVX 12L is a great scope. I particularly like that it is a bit slower than most 12" dobsons. It is a telescope that I have seriously considered in the past. You were lucky to find a very good one in the s/h market for an excellent price. For dobsons of 12" aperture or larger, I prefer a truss but a solid tube has advantages of course. I agree with you about the limitations that the UK weather can cause on a high quality mirror. There are other important factors though, like mount and focal length. I'm quite fussy about the movements of a telescope and much prefer observing standing up. 

 

p.s. just expressing my point of view openly. I believe that a telescope is a personal thing and as such we can have different tastes and opinions! 

Edited by Piero
  • Like 3

Share this post


Link to post
Share on other sites

Maybe we'll just leave you to it then!? :D

Only joking.

Mine is more of a pipe dream list than a wish list!

But I'm hoping that if I've been good I might get 12" dob when I retire. :D

  • Like 1

Share this post


Link to post
Share on other sites

The movement on my mount is a result of Shanes craftsmanship - simple teflon pads, in the right places, and the scope not only moves smoothly but equally importantly it stays where you point it. The dobsonian mount is such a good design when well executed :icon_biggrin:

  • Like 1

Share this post


Link to post
Share on other sites
3 minutes ago, John said:

The movement on my mount is a result of Shanes craftsmanship - simple teflon pads, in the right places, and the scope not only moves smoothly but equally importantly it stays where you point it. The dobsonian mount is such a good design when well executed :icon_biggrin:

it's a fabulous design indeed! 

Share this post


Link to post
Share on other sites

Perhaps Piero you could consult with David Lukehurst. 

  • Thanks 1

Share this post


Link to post
Share on other sites

Piero - I also took a long time to choose a Dob.  I settled on the 10inch Bresser and am very happy with it.  You could go larger with a truss type,  but I figured collimation would hold  better with a solid.  I've had it for many months,  and it has only needed the occasional tweak .  And since my skies are not great , I doubt a bigger ap would give better views.  And I couldn't manage anything bigger anyway! 

Enjoy the deliberations! 

Doug.

  • Like 1

Share this post


Link to post
Share on other sites
7 minutes ago, scarp15 said:

Perhaps Piero you could consult with David Lukehurst. 

Thanks for the advice Iain. I will. :)

  • Like 1

Share this post


Link to post
Share on other sites

Telekits....John Nichol mirror.

  • Like 2

Share this post


Link to post
Share on other sites
2 hours ago, Piero said:

@bingevader  mm.. I'm not a great fan of ultra-light "naked" dobsons. Dobsons like Sumerian have portability in mind. Said this, from my standpoint sturdiness and ultra-portable do not go well together. To make it short, my main concern about ultra portable dobsons are collimation holding, thermal issues + dew formation with the primary mirror as this is (in my opinion) too exposed, particularly considering the UK climate.

@John  :) The OOVX 12L is a great scope. I particularly like that it is a bit slower than most 12" dobsons. It is a telescope that I have seriously considered in the past. You were lucky to find a very good one in the s/h market for an excellent price. For dobsons of 12" aperture or larger, I prefer a truss but a solid tube has advantages of course. I agree with you about the limitations that the UK weather can cause on a high quality mirror. There are other important factors though, like mount and focal length. I'm quite fussy about the movements of a telescope and much prefer observing standing up. 

 

p.s. just expressing my point of view openly. I believe that a telescope is a personal thing and as such we can have different tastes and opinions! 

Hi Piero I’ve never come across any of the concerns you mentioned above with my Sumarian colimation holds really well and takes only minutes as for the dew with the shroud fitted its the same as any if not slightly better airflow with the two fans below the primary it works so well movement on theese scopes is a dream and they are very stable 

Share this post


Link to post
Share on other sites

Sorry, I didn't want to sound aggressive with my previous post. 

Share this post


Link to post
Share on other sites

Ultralight dobs can be of excellent quality if built using quality parts...Mapstars 22" is the best I've seen...stunning scope.

  • Like 1

Share this post


Link to post
Share on other sites

A 10" F6.3 David Lukehurst build has recently come up on UKAB&S £950. 

2 hours ago, estwing said:

Telekits....John Nichol mirror.

I believe that David Lukehurst can install these to.

  • Like 1

Share this post


Link to post
Share on other sites

Hi Piero

I can heartily vouch for a Lukehurst truss dob. David built one for me last year. A 14" 1/14th wave with Hubble Optics. It holds collimation exceptionally well even after dismantling, a trip in the car and reassembly. The views are magnificent when conditions allow. Happy hunting. 

Ally

  • Like 2

Share this post


Link to post
Share on other sites
8 hours ago, Ally8446 said:

Hi Piero

I can heartily vouch for a Lukehurst truss dob. David built one for me last year. A 14" 1/14th wave with Hubble Optics. It holds collimation exceptionally well even after dismantling, a trip in the car and reassembly. The views are magnificent when conditions allow. Happy hunting. 

Ally

Thank Ally. When you have some time, could you post a photo of the mirror cell from the back of the mirror box, please?

Share this post


Link to post
Share on other sites
Posted (edited)
9 hours ago, scarp15 said:

A 10" F6.3 David Lukehurst build has recently come up on UKAB&S £950. 

I believe that David Lukehurst can install these to.

Thank Iain, it looks like a nice scope. I'd just like a bit more aperture. 

Edited by Piero
  • Like 1

Share this post


Link to post
Share on other sites

I’d pop along to a couple of the larger star parties to get a look to some examples in the flesh. The Sumerians are a lot more robust than they look.

Agreed re Mapstar’s big Dob. Damien’s attention to detail is phenomenal.

Paul

  • Like 1

Share this post


Link to post
Share on other sites
Posted (edited)
On 05/03/2019 at 07:29, Piero said:

Thank Ally. When you have some time, could you post a photo of the mirror cell from the back of the mirror box, please?

Piero,

Here are various pictures of my Lukehurst. Its the "Deluxe" standard edition. But I customized pretty much everything away from Davids standard spec.

1. I imported Powered groundboard system, 10K encoders, DSC cables & 20" Telescope Cover from AstroSystems (USA)

2. I imported a Nexus push-to from Astro Devices (Australia)

2a. I imported a Tablet Stalk from Markless Astronomics (USA).

3. I purchased a 2.5" travel Feathertouch focuser and Dob mounting plate from FLO

4. I specified a cooling fan for the main mirror.

5. I dropped the standard finder scope and asked David to install a Baader finder shoe for my Baader Skysurfer 5.

6. I bought the cats eye centre spot and posted to David for installation on the primary mirror.

7. I purchased a Kendrick secondary heater and Kendrick mini dew controller (for the UTA) which David installed very neatly including a system where the secondary dew heater wiring passed up inside the truss tubes!

David was happy to install all the electrics and encoders (he made up all the arms etc needed to mount the encoders). He installed a lovely balance system free of charge too!

- my personal contribution was to buy various cables, fuses & connectors, then make up all the cabling necessary.

I went for a Oldham Optics mirror (although the grind was completed by John Nichol) and I have Orion Optics Hi-Lux coatings.

Here are some random pics taken in the 2 years that I have had the scope (HTH!)

b4.jpg.762d3e5277c3982937c542fb3b3b50f8.jpg

mirrorcell1.jpg.6568004f88d8b9992c9a0bef90353ed1.jpg

 

 

dob1.jpg.023ab736b79aefbeeb1c5411f0797d20.jpg

dob2.jpg.2bdf9096649ed91fd50688c169425563.jpg

 

 

dob9.jpg.4026d26630db0a95ae9894f1573ef85e.jpg

 

rocker_box.jpg.3cba16777d14ac4cc1bc4ec30a1f6afa.jpg

 

dob7.jpg.e5d4a3b6e4952a142c7281e2b9a317a8.jpg
 

As said above, collimation rarely needs touching. I dont move the scope much and the star diffraction rings are always perfect. Occasionally I feel sorry for my Howie Glatter tools and give them a tweak!

Its best to phone David up and talk to him about what you want. He will build whatever you specify! I imported all the bits and bobs myself to save David messing with customs etc and then I travelled to Nottingham to see the build and deliver all the lovely scope stuff that I had accumulated!

Over the 4 months that I waited for my scope, we exchanged many emails (David is always quick to respond) and I decided to travel to Nottingham to collect my scope in person (to take delivery) although David does offer a personal delivery service (in his own car!)

He is a nice man to deal with and whats better than a UK made scope!

Alan

Edited by alanjgreen
  • Like 6
  • Thanks 3

Share this post


Link to post
Share on other sites

Thanks for your input, Alan. Very informative. You've got a great telescope.

Share this post


Link to post
Share on other sites
Posted (edited)

@alanjgreen

Do you have bobs knobs for the secondary?

Does David install Glatter sling for the primary?

Edited by Piero

Share this post


Link to post
Share on other sites
Posted (edited)
15 hours ago, Piero said:

@alanjgreen

Do you have bobs knobs for the secondary?

Does David install Glatter sling for the primary?

 

Do you have bobs knobs for the secondary? No

There are three secondary adjustment screws (the screws take an allen key type fitting). David gave me an allen key screwdriver that fits these screws. The whole secondary assembly is held in with a large fly-wing nut (like the 3 on the primary). Here is a pic I found on the internet. The three adjustments screws are seen on top of the secondary assembly.

- with the top external ring nut removed then the whole secondary assembly can be unthreaded and removed from the UTA (for cleaning etc).

image.png.2c5c3e2ba0c5fa428a49e0d68c33b1b5.png

 

Does David install Glatter sling for the primary? No.

The primary is held in by three small right angled metal pieces (with some soft material on the inside) positioned at 12, 4 & 8 o'clock. The three small metal pieces are attached to the side supports with small screws (see second small pic) and are obviously removed in the large picture so that I could get the mirror out in the photos above, This is one of the side supports...

zzz.jpg.1fbaafc1e73ea1b67f5eb3df43c48089.jpg image.png.87fcf66e4ec91113513ec7090fe95aa2.png

In addition, I would say that the mirror box is a very clever design and you just tilt, lift & pull the mirror cell out very easily (although it’s a two man job with a 20") - you can see the letter box hole in the base of the mirror cell in the posts above - this is to pull the cell out of the mirror box.

image.png.abb07fdd92bd6cd94eed017bf6287b48.png

Alan

Edited by alanjgreen
  • Like 2
  • Thanks 1

Share this post


Link to post
Share on other sites

Interesting to see the mirror cell/box detail for a Lukehurst design - hadn't seen how he approaches it before.

Lovely scope ;)

  • Like 1

Share this post


Link to post
Share on other sites

I recall observing through a 20 inch David Lukehurst made dob a few years ago at the SGL star party. M13 and M51 were the objects I chose to view. I won't forget those views in a hurry. Absolutely jaw dropping :shocked:

 

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Piero
      Could someone post a photo of the altitude bearing, please?
      I would like to know how this is attached to the tube, its thickness, and whether it is removable. 
      Thanks a lot!
      Piero
    • By Ben the Ignorant
      I wouldn't want to miss observing the Sun in a full-size 300mm filter, the detail compared to smaller instruments is such a joy to see. I do have an off-axis mask for my 300mm dob but not all the time. If daytime seeing is too bad for such a large scope, I'll switch to a smaller one, but the extra resolution and ease of spotting micro-detail thanks to the brightness is something I can't do without.
       

      A sheet of 500mm wide Baader fillm allowed me to craft this. I had enough left to cut several smaller filters.
       

      To protect it I made a storage box from cardboard of obvious origin. The box had to be custom-made to save space in my dwelling, and it also hosts a bahtinov mask for nighttime. At f/5 fine focus is not too hard with the smooth single-speed focuser, but in order to enjoy moments of clarity immediately at high power, I pre-focus with the bahtinov, which sees through turbulence, what a nice invention, and simply wait for calmer air. No need to rush to fine focus and waste precious moments. This mask needs to be copied in some sort of plastic, the cardboard trial proved the number and width of the slits are fine.
       

      The rear of the filter shows the four clips mating the four button screw heads outside the tube.
       

      And this lateral view shows the sandwiching. A rigid backing plus two layers of lightweight neoprene foam cut from a cheap mat in tiger-stripe deco, its poor taste matching its 7€ price. The bottom sheet used to be a shower booth panel, my neighbor had in its garage. Hey, do you need that? No? Okay, thanks!
       

      The Baader film is held between the neoprene sheets by staples and many strips of tape. The neoprene is held to the shower booth sheet by little collars, and its edges are sewn together for a finished look. Oversize 10mm stitches didn't take too long to do, and the foam layers can be separated for replacing the film, something glue would prevent. Holes in the neoprene allow to check that the clips' bolts are always tight.
       

      Close-up of a clip. They are made of a material whose name I forgot, I only remember it is made in the UK (thanks, guys!). This is a PVC foam that's much easier to cut, drill and sand than full-density PVC, and it's much lighter (thanks, air bubbles!), which is essential for an item that's at the front of a scope where leverage is maximal.
       

      My GSO dob has four of these screw heads, one for each spider vane. They proved very convenient for attaching the filter. The black knob is an add-on to move the scope without having to grab the large tube with both hands.
       

      Pretty obvious what we're seeing here. Note the clip is flush with the tube, and pressed hard against the scope's metal rim for a very secure and tight fit. Only four clips but eight attachment points, really. Building this with tight tolerances was more lengthy but more reassuring.
       

      It is impossible to disengage a clip by accident because tolerances are too narrow, and the shower booth plastic tough spring action doesn't allow it. But should it happen three clips would hold the filter safely. All three layers of frame material are flexible, so, to remove the filter from the tube you just bend it at a corner while you lift the clip, and the clip disengages.
       

      I already rebalanced the dob by pulling the 7-kilo mirror to the rear thanks to shorter and tougher cell springs but I'm working on a sliding counterweight made of pliable steel ribbon. Adhesive felt pads protect the paint. Thanks to the large hole the 300mm filter is not too heavy (and it's used without the finder) but the off-axis mask has only a 115mm hole, so it's heavier and may require this. While I study the combinations of heavy or lightweight eyepieces, finder/no finder, mask, filter, I can change the experimental counterweight by cutting off or adding pieces of steel ribbon. Little mounting nuts and bolts through the many holes, there's always one at the right place.
       

      Ever hated to feel the Sun while loving to watch it? If you have no sunshield you did. Heat is a discomfort on the head, and light kills off contrast. So I cut a plastic folder in this weird pattern to allow sliding it between the shower booth plastic and the neoprene mat.
       

      When it's stuck there it makes quite a large area of shadow, that's such a relief. But that's also only a prototype that wants to be made again with a better material. Has to be opaque, quite thin, very lightweight, but rigid enough. I'll stumble upon the right material sooner or later.
    • By LuminousCRO
      Hi Guys,
      I wondered if it's possible to attach a mirrorless camera (that is a camera that is not able to remove it's lens) to a telescope. Is there an attachment or a camera holder?
      Luminous  
      Thank you, in advance
    • By Susaron
      Dear all,
      Recently I purchased one of these dobsons from ES following the good critics I read in several forums.
      The Gen II includes some improved features with respect to Gen I, 2 Nylon pad brakes, Virgin Nylon alt and azimuth support bearings (instead of plastic), counterweight bar included with a couple of 1kg counterweights, a classical ES dovetail for the finder.
      Some of these improvements were demanded by Gen I users, and are highly appreciated, but there is still some minor improvements that the final user has to apply. I will describe them lately.
      The set up is very fast, less than 15 minutes, though the assembly of the upper cage needs some patience the first times is done.  Regarding the optics, It is superb, though in my opinion the 75mm minor axis secondary is too big (other similar modes in that range use a 63mm one), it provides full illuminated views on my ES 100 degree eyepieces, the stars in the background seen in clusters like the NGC457 are astonishing.
      The main mirror cell support is a mix of support concepts, a nine point mirror cell support with a couple of rubber wheels at 90 degrees, and 3 glued slings to the mirror laterals screwed to the back of the mirror cell support, provide lateral support for the mirror. The collimation as in Gen I is done from above in less than 5 minutes.
      In the first light in semirural skies the views confirmed the good optics, as I said specially in star clusters the amount of stars which could be seen in the background increased with respect to my 200PDS, the globular clusters were literally smashed, and small planetary nebulae like M76 showed internal details.
      Coming back to the cons, as in any Chinese made product there are quality problems not solved in this Gen II, the paint coatings from the secondary cage just jumped when I changed the position of the truss brackets.
      When I tried to open the main mirror box for the first time, the scratched the yellow paint from the altitude bearings, a tolerances problem which I solved adding 2mm nylon washers between the altitude bearings and the mirror box.
      More improvements to make on your own are to make a plywood cover to prevent moisture on the main mirror while waiting for the night, to put foam pipe covers around all the tubes, they make the winter usage of the scope more comfortable and at the same time help with the vibrations damping (which even with a heavy ES 20mm 100d EP where almost insignificant).
      One more thing to add is a PWM motor controller, the fan only work at full speed, and there are so many nights when the temperature gradient does not fall fast and the fan speed can be left at a lower regime to save batteries.
      In brief, the ES12'' Gen II, it is the Dobson truss scope with the lowest price in that aperture range, the optics is damn good, the mechanical improvement done in the GEN II, improve a lot the vibrations, and the movements of the scope, though a better control on the tolerances and the paint process should be done.
      I attach some pictures taken at home and while the first light.
      Cheers.
      Mario.



    • By 25585
      Given that assembling a skeleton tube dob in the field requires collimation checking, what models of say F7 to 8 upwards, 8 to 10 inches aperture are available, which would not exceed an OTA vertical height of 72inches/6 feet?
      I like Portaball scopes, do they come with shrouds, or can shrouds be bought separately for them?
       
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.