Explore Scientific 12"" UL dob gen 2 + gear

[Och_Aye]

I've got my eye on a 12" dob and would like someone to tell me if my thinking is sensible or if they have any better ideas!

The background is that I live just outside of York, so 54 degrees north in a bortle 4 area.  I'd like a scope purely for observation of DSOs but can also do some planetary.  It'll be put away every night and regularly put in the car to get outside of my village, which isn't far but a necessary trip none the less.

I'm thinking a 12" flex tube dob is the best combination of cost, aperture, portability & storage based on an overall budget of £3k.  The ES option seems to be better for my needs than what SW offer.  I'm also thinking that I can go mad and get a 21mm Ethos to maximise glass quality and get that FOV, using 2x and 4x 2" powermates in place of other EPs.  I'd get a ND filter for use on the moon, but what others should I get?

Is this a sensible approach?  Are there any other approached I should consider?  What other gear will I need?  I'm thinking I'll need a laser collimator and a self-built levelling platform (for when I'm out & about).  Will I need (or disappointed if I don't get) a coma corrector, and if I do is ES' own a sensible option or should I stump up a bit more for a paracorr, or is that just burning money?

One last question, can I use a 90 degree diagonal with a dob to make looking near the horizon easier?

cheers

[John]

I can't answer all your questions (others will I'm sure) but:

- a 90 degree diagonal is not usually used with a dob. They require inwards focuser travel which dobs don't usually have so eyepieces will not reach focus.

- Be aware that using a 21/20mm 100 degree eyepiece with the Powermates creates a very long and heavy stack hanging out of the focuser. The combination works, optically speaking, but will put a lot of strain on the focuser. Here I was playing with an Explore Scientific 20mm / 100 which is a similar size to an Ethos 21mm:

 

[Och_Aye]

Cheers, I'm glad I asked now!

[scarp15]

19 hours ago, Och_Aye said:

 

I'm thinking a 12" flex tube dob is the best combination of cost, aperture, portability & storage based on an overall budget of £3k.  The ES option seems to be better for my needs than what SW offer.  

Hi, I cannot comment on the ES option, yet a 12" manual flex dob is a good practical contender for your intended use. The focuser may need an upgrade, as is popular with users, to a MoonLite CR1 or 2 and a few smaller mods required, but this is a good all rounder and very good at deep sky subjects from a dark site. Which ever dobsonian you choose, include a shroud and consider some rolls of flocking material to black out part of the inside of the tube. Factoring in ultra wide low power eyepieces definitely, the used markets are worth keeping an eye on, i.e. Panoptics, Naglers and if budget is OK, Ethos as well as the many other good branded alternatives. A collimation tool is straight forward. Dim red light and a good quality filter i.e. O-III for the arrival of Cygnus. Also a good adjustable observers chair. As John mentioned, no to a 90 degree diagonal, a chair on a low setting may help when positioned at low elevation and conversely, the 'dob hole' (at zenith) is a little bit disorientating,  yet not unsurpassable, just need to get tactile and a little dob hugging gets you there. Another alternative is a used Orion Optics UK 12" solid tube, in which the ota can be adjusted inside the tube rings to align the focuser for a more comfortable viewing position, as well as aiding with balance.

[johninderby]

The ES12 actually comes with a decent CNC R&P focuser so no need to upgrade it to a Moonlite as it should handle a greater load anyway.

Pity the SW doesn’t come with a better focuser.

Edited May 31, 2021 by johninderby

[Och_Aye]

Thanks guys, appreciated.  Looks like £3k isn't going to be enough but I can get smaller parts & filters through christmas pressies!

[Nyctimene]

22 hours ago, Och_Aye said:

  It'll be put away every night and regularly put in the car to get outside of my village, which isn't far but a necessary trip none the less.

With this in mind, I'd go for a slightly smaller and more lightweight solid tube Dob. A 12" ES, even the UL, is heavy (the ES mirror box alone specified with 50 lbs!), so, after a few weeks of enthusiasm, you will possibly find yourself in the situation not wanting to take out all the heavy gear, load it into the car, drive, assemble, await cooling down, collimate.... and reverse two or three hours later, esp. when the weather forecast is uncertain. All the small tasks will add up, like the Liliputians strings fastening Gulliver to the ground, to prevent you from frequent and joyful observing; don't underestimate them.

Orion Optics UK offer a 10" f/4.8, with a total weight of just 23 kgs, -( less than the ES mirror box alone), the OTA at 11 kgs, and would be well within your price range; have a look:

https://www.teleskop-express.de/shop/product_info.php/info/p656_Orion-UK-VX10-250-mm-f-4-8-Dobsonian-Telescope---1-8-Lambda.html

Place the tube on the rear seats, the base in the trunk; and you are much faster, with less hassle, when starting observing. Short primary collimation, no alignment etc, just sit down and enjoy.

(Btw.; there are even more lightweight dobsonians - during the next weeks my new (used) 12" f/5 Hofheim Instruments traveldob will arrive! Total weight just 12 kgs; now out of production - have a look:)

http://www.hofheiminstruments.com/fotos.html

Stephan

Edited May 31, 2021 by Nyctimene