12" non-GOTO Dob suggestions

[discardedastro]

Righto, so - trying to finally decide on a 12" dob kit for <~£1k. I've looked at the usual suspects and FLO will just about get me there on a Skywatcher 300P FlexTube plus shroud and dew shield, but I think I need to add a focuser as I know I'll get annoyed with a single-speed focuser, so that knocks things up to £1300.

I think this is likely to be a reasonably good option in that I know the SW glass will be OK and the FlexTube is going to be a nicer thing to store than a full tube etc. Being a popular model it's also something quite a few accessories are available for with easy mounting solutions, such as encoders - these I'll add later with a Nexus DSC, rather than using GOTO. The focuser will be a Baader Steeltrak Diamond NT as I've been very impressed by the Steeltrak Diamond I'm using on the imaging 200P, so I know that'll be a great thing and work well.

However I know there's other options out there - the Meade LightBridge has a dual-speed focuser and looks fairly sensible otherwise, Explore Scientific's Ultra Light second generation series looks quite promising and similarly has a dual-speed focuser included, and GSO's (non-truss) 12" Dob also has a dual-speed focuser and what looks like a better bearing system. Price-wise they're all there or thereabouts and look like they might be better options.

This is purely for visual use - I have the 200P/EQ6-R Pro rig for imaging - hence going for a big (but not silly) Dob. Moving it isn't an issue but I figure 12" is the sensible limit for solo maneuvering in and out of an awkward house. Demounting the camera and converting everything back to visual is a fairly lengthy task (esp to demount the focuser etc) so not something I want to be doing. I'm going to be doing this rig in stages like I did for the imaging rig but good motion control and focus control to me feels like a prerequisite to not getting annoyed at the kit during a session.

Would welcome any thoughts or suggestions from more seasoned observers than I!

[Dr Strange]

In terms of size and somewhat in terms of weight the Explore Scientific 305mm Ultra Light is an excellent option. Serge at Astro Devices (maker of the Nexus DSC which is a fantastic bit of kit and I love mine. I just upgraded my DM6 with his 311k tick encoders) makes a complete kit for it too. The scope is also in your budget. Unfortunately FLO doesn't carry it. I love FLO for their service! When I can't find something over here they are my go to shop in the EU. Here is a link to the scope:

https://www.explorescientific.co.uk/en/Telescopes-es/Dobson-Series/EXPLORE-SCIENTIFIC-Ultra-Light-Dobsonian-305mm-GENERATION-II.html

[discardedastro]

3 hours ago, Dr Strange said:

In terms of size and somewhat in terms of weight the Explore Scientific 305mm Ultra Light is an excellent option. Serge at Astro Devices (maker of the Nexus DSC which is a fantastic bit of kit and I love mine. I just upgraded my DM6 with his 311k tick encoders) makes a complete kit for it too. The scope is also in your budget. Unfortunately FLO doesn't carry it. I love FLO for their service! When I can't find something over here they are my go to shop in the EU. Here is a link to the scope:

https://www.explorescientific.co.uk/en/Telescopes-es/Dobson-Series/EXPLORE-SCIENTIFIC-Ultra-Light-Dobsonian-305mm-GENERATION-II.html

Rother Valley seem to have the ES in stock and have done me well before, though I'll still be going for EPs from FLO I think.

From reading up on them, looks like common mods are to fix some problems with rivets fouling on the az bearings and completely surround the secondary holder, but focuser gets good reviews and overall looks alright. Not averse to some scope mechanics DIY if the optics are basically sound. Do you find the offset spider vanes produce odd spikes?

[Dr Strange]

There were rivet problems with the Gen 1 scopes. If you can, get a Gen 2. All of the issues reported previously were fixed. 

In my experience the vanes were not a problem and there were no spikes except on the brightest of objects. But the caveat to that is I am not bothered by spikes. I am horribly bothered by poor figure, wooly stars, and most especially CA. So YMMV.

[John]

Can the eyepiece angle be changed, ie: rotated, on the Gen 2 scopes ?

Sticking straight of of the side like the one in the picture is not the most convenient eyepiece position I think.

An angle like the one in this picture seems to work best:

 

[Ships and Stars]

I do like the look of the ES dob, but I also have the 300p Flextube and love it alongside the 20" 500p, so the bar is pretty high for the 300p I suppose.

It is very fast to set up and the truss rods can be locked in a shorter preset position to use binoviewers at native magnification without a glass path corrector.

The base is fairly big for what it is, but certainly stable and can be easily carried with one hand while I use the other to open and close doors on the way outside. Speaking of which, it just fits through my narrow doors at home. I think I set it up before in under 4 minutes without racing. The collapsible tube makes it a lot more manageable to move around and transport in a car and store. I have a black foam camping mat that I was going to make a dewshield, but haven't bothered yet as it's never dewed up, even the secondary has stayed clear. Someone had a trick to put the foam tube inside the trusses, rather than around the outside, and it looks even tidier than the astrozap dewshield which is pretty expensive for what it is I think.

The azimuth bearings are very smooth and the four nylon (or some sort of plastic) altitude bearings, although rudimentary-looking, work smoothly as well and the scope has 'dob knobs' to adjust altitude easily. It's a breeze to move around and point if you want to hop around the night sky quickly. The more weight you put in the focuser, e.g. a coma corrector and 100deg EP, the easier it seems to adjust altitude with a gentle nudge.

It does have the single-speed focuser but it doesn't bother me because it snaps to focus quickly and I rarely finding myself hunting back and forth for fine focus. Having said this, I wouldn't be opposed to installing a dual-speed in the future.

I do like the look of the mirror box on the ES model and how it nests together for storage/transport. You would need a full-length dew-cover for the ES as well.

Finally, I suppose the key is optical quality. I've used mine up to 333x on Venus and find myself using the 9mm 100deg APM at 167x everytime I have used it lately. It gives some very pleasing, sharp views.

The ES would be interesting in a way because I don't think a lot of people have them, if that counts for anything. It does look the business and looks well thought out.

Meanwhile, the SW flextube base is fairly well-made, but the pressboard/chipboard MDF might need a coat of clear lacquer to prevent moisture from getting to it over the years - I have clear epoxy resin for boat building I was going to seal it with but so far it still looks new.

The Nexus DSC looks interesting - I wonder if that can be fitted to a flextube?

I don't think you can go too far wrong with either of them! 👍

Edited April 4, 2020 by Ships and Stars

[Dr Strange]

3 hours ago, John said:

Can the eyepiece angle be changed, ie: rotated, on the Gen 2 scopes ?

Sticking straight of of the side like the one in the picture is not the most convenient eyepiece position I think.

An angle like the one in this picture seems to work best:

 

I don't think so but I don't remember. I don't remember it being a PITA either from a viewing perspective. Unfortunately for me Dob's are not an option any longer due to my numerous injuries from rugby and other stupid things I did when younger. So I am limited to SCT's, DK's, some Mak's. and refractors now.