In the market for a dobson

[Piero]

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 March 17, 2019 by Piero

[bingevader]

Sumerian?! :)

[John]

Your "wish list" seems very similar to mine Piero

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

 

 

 

 

[Piero]

@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 March 4, 2019 by Piero

[bingevader]

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

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.

[John]

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

[Piero]

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

it's a fabulous design indeed! 

[scarp15]

Perhaps Piero you could consult with David Lukehurst. 

[cloudsweeper]

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.

[Piero]

7 minutes ago, scarp15 said:

Perhaps Piero you could consult with David Lukehurst. 

Thanks for the advice Iain. I will.

[estwing]

Telekits....John Nichol mirror.

[garryblueboy]

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 

[Piero]

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

[estwing]

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

[scarp15]

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.

[Ally8446]

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

[Piero]

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?

[Piero]

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 March 5, 2019 by Piero

[Paul73]

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

[alanjgreen]

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!)

 

 

 

 

 

 

 

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 March 18, 2019 by alanjgreen

[Piero]

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

[Piero]

@alanjgreen

Do you have bobs knobs for the secondary?

Does David install Glatter sling for the primary?

Edited March 5, 2019 by Piero

[alanjgreen]

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).

 

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...

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.

Alan

Edited March 6, 2019 by alanjgreen

[niallk]

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

Lovely scope

[John]

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