Explore Scientific 16" F/4.5 Ultra Light Dobsonian

[Ags]

I am idly dreaming about the observatory I will set up when we move several degrees south next year. We should land in Bortle 4 which is a chunk better than 8 - although I read Bortle 4 is very wide with good end and a bad end...

I think my little HEM15 is all I need for deep sky AP, EAA, visual smartscoping and so on, but I do want something bigger - a lot bigger - to get really close in on the Moon and planets. I need a lot more aperture to compensate for my snowglobe eyes that won't let me use small exit pupils. Also I want to go as far as I can with planetary imaging, and that is one field in which aperture is absolutely deterministic.

I have been designing a dobservatory - a low-walled ROR obsy to house a larger dob on an eq platform. The dob would be permanently set up in a fixed position, but keeping weight low would still be a priority as things need maintenance and even the strongest eq platform can do with less load... The ES 16" caught my eye - it seems quite a good price and the overall weight is not too bad at 38 kg, although the mirror box is 23 kgs.

If money is no object (really depends if I can take my work south with me) then the Taurus T400 is the other option at twice the price - 31 kg total weight, heaviest component 18 kg, and 1/8 pv optics.

Does anyone have experience of the ES - how is it mechanically and optically? I think with an EQ platform and starsense for DSOs it should be pretty nice.

 

Edited April 11 by Ags

[vlaiv]

I had a chance to use 12" version of ES scope few weeks ago.

A friend of mine just got it in time to do Messier marathon with it this year. Three of us were in the team and we took third place. Rules of marathon state only one scope to be used per team - so we went with new scope. Probably not the best choice as we only had ES68 28mm eyepiece as our lowest power EP - which gave us ~ x54 magnification and somewhat narrow FOV for quick finding of the objects.

General impressions that I got from that night:

- scope gathers a lot of light

- we had lower contrast due to truss design and no proper shielding (there was no time for "sock" to be made / ordered).

- mirror box is quite heavy, and is two man job to comfortably transport / set it up. Rest of the scope is very light weight. Putting top cage on truss poles is again better done with a helping hand (because it needs to be held securely while tightening screws and aligning everything).

- Collimation was a breeze (with laser collimator) and scope held collimation well for the duration of the night.

- it was fairly easy to use / point - much like any other dob of similar size.

- balance was issue at low altitudes. Scope comes with counter weights and counter weight bar - but due to excessive top loading - 50x9 RACI finder, red dot and telrad (although red dot was redundant next to telrad) and 500g eyepiece - scope slipped down if not held by hand when pointing low above horizon.

Friction mechanism to stiffen up altitude motion was rather flimsy in my opinion.

- focuser and finders are at an angle I was not used to - but I managed to use the scope without issues

- scope gives very nice sharp image at low to medium powers. We did not do any high power work with it yet so I can't tell how good the optics really is.

[Ags]

Thanks, that's a lot of detail! It does seem unfortunate the design puts the bulk of the weight into one component.

[fwm891]

Dakota Starry Nights reviews on YT are quite in depth for these Dobs...

[vlaiv]

4 minutes ago, fwm891 said:

Dakota Starry Nights reviews on YT are quite in depth for these Dobs...

That review seems to be from 2015.

As far as I know, there has been at least two revisions of these truss scopes. Don't know if latest revision resolved issues with original?

[Ags]

I'll have to think about the weight. The Stella Lyra 16" is a great price and looks mechanically superb. If I ever need to move the thing, I'd need to summon a posse.

Edited April 12 by Ags

[Mr Spock]

3 minutes ago, Ags said:

The Stella Lyra 16" is a great price and look mechanically superb.

I've had a look through one. Astonishing view of the Witch's Broom from B4 skies. That was with a 31mm Nagler and OIII filter. It was really bright and jumped out at you.

[seven_legs]

I had Explore Scientific Ultra Light 16" Dobsonian Telescope Gen II awhile back, its a great scope with lots of pros and cons.

the primary mirror box i could carry myself easily, but it is easier with two.

The Pros:

The easiest and quickest telecope i have ever collimated.

The scope can be set-up in about 10 minutes at most.

The Views are amazing, 

I found the balance of the scope was fine and the scope movement was smooth.

The Cons:

I did not like how the primary seemed to be held in by straps. If you tried to stand the main box on its side you could hear the mirror move.

The mirror is like a grass and dirt magnet even when using a lightshroud.

The primary mirror cannot be removed from the box for cleaning, or i could not see a way of doing it due to the straps. So i would clean the mirror within the main box itself, which was not a big deal really but i would of prefered to be able to take out.

My main gripe was the upper secondary assembly holding the secondary mirror is an open design and the scope lightshoud does not cover it. So i used flocking to fill the gaps which work very well. I got the idea from a youtube video.

Conclusion:

Great scope, the cons are minor niggles. If you are good with your hands then this scope could be a modders dream.

Of course there are better designed scopes out there but might cost more.

The only reason i got rid of the scope was because i lost my job during Covid and had to sell for finanical reasons.

hope that helps

[Ags]

Great info, thanks @seven_legs!

The scope would be set up permanently in my dobservatory, so I think I should be able to keep the mirror clean.

I thought straps were the usual thing for large mirrors, to prevent pinching the optics?

Can I ask how the scope performed at mags above 300x?

Edited April 13 by Ags

[seven_legs]

23 minutes ago, Ags said:

Great info, thanks @seven_legs!

The scope would be set up permanently in my dobservatory, so I think I should be able to keep the mirror clean.

I thought straps were the usual thing for large mirrors, to prevent pinching the optics?

Can I ask how the scope performed at mags above 300x?

To be honest i mainly used my 31mm Tele Vue Nagler 82º Eyepieces type 5 eyepiece which gives about 59x mag. But that yielded great detail on many objects. It was a shame that, at the time of my ownerships most planets were not in view. The only time was when mars was at oppostion,( i think.) i got one chance to see it low down, of course there was a massive dust storm that covered the planet. Even then the planets disc seem large in the field of view.

As for the straps, you may be right, i don't know.

[Ags]

Yes I remember that Mars opposition - I travelled to the Canary islands for a better view, and Mars was completely featureless!

OK, so the plan is: ES 16" dob, Geoptik EQ platform, Starsense. I'll be able to manage all components by myself if needed, and everything will be easy with an assistant. 

I see the ES dob is a bit tricky with balance issues, but I am not one to change eyepieces frequently (or a fan of big eyepieces) so not too worried about that. 

Edited April 14 by Ags