ES Twilight I

[Ags 1,892]

I am currently using a 150PDS on an ES Twilight I mount and so far I am underwhelmed by the stability. I have gotten things to more or or less tolerable levels by using vibration suppression pads and bolting wood plates to the somewhat flexible dovetail arm. Also, i have tempered my ambitions regarding migh magnifications, and I don't dare to go above around 130x. The question is how do I get a better performance? I like working with the mount depite its shortcomings but I'm not too happy with the telescope - Newtonians don't give me the clean views my old mak used to give me. The scope is rubbish at double stars which are kind of one of the main things you can look at in a city 

Moment of inertia of a bar increases as the square of radius, so a shorter telescope should help. The three that offer enough aperture are the Orion Optics OMC140 (3.5kg), C6 (3.5kg), C8 (5.5kg) and Skymax 150 (5.6kg). They are all short enough, and I tend towards the Skymax because I like Maks, and I haven't been that impressed by the views I've had through a C8. But the question is: has anyone had any experience with mounting any of these scopes on an ES Twilight I?

 

 

[TSRobot 158]

I bought the ES twilight from OOUK which they said was there own mount, but was clearly the ES twilight when it arrived. I put my C8 on it but the slow motion controls where very iffy with the weight of the c8 so had to send it back. I then went for a Skytee2 which is brilliant though this needs a counterweight so gets much heavier. The Skytee fitted onto my Vixen Hal130 tripod with an adaptor that FLO got for me. I don't have the C8 any more, but the C8/skytee setup worked very well.

[ronin 3,800]

Well the 150PDS is specified at 6Kg so that is 13.2 lbs and the ES Twilight I is rated at 15lbs. So the scope is pushing the top limit of the mount.

Now Skywatcher will likly not weigh the tube with say finder and eyepiece, maybe not rings and dovetail, makes the result appear better and all they give is "Tube weight". So the real weight could be fractionally higher in use, and equally ES might be a little optimistic on the load. It might hold 15lbs but how comfortably it will hold 15lbs is probably open to debate.

Suspect the Twilight is comfortable at 12lbs and 15lbs is a more realistic weight for the OTA.

Clarity, the scope is for imaging, maybe a coma corrector would help, it is on the fast side. The standard question of how well coiilmated it, guess an f/5 needs checking at regular intervals (weekly). And a reflector is not the sharpest of scopes, the secondary assembly and vanes impact on this aspect.

When everything is considered what you are experiencing is perhaps not that unexpected.

[davyludo 246]

Would you consider a different mount in order to get a better viewing experience? 

Something like an AZ4, maybe AZ5 (on better tripod) or Vixen Porta II if you like the slow motion. Rather than spending money on a new scope to find that you have similar issues to to limitations of the mount.

[Ags 1,892]

4 hours ago, TSRobot said:

I bought the ES twilight from OOUK which they said was there own mount, but was clearly the ES twilight when it arrived. I put my C8 on it but the slow motion controls where very iffy with the weight of the c8 so had to send it back. I then went for a Skytee2 which is brilliant though this needs a counterweight so gets much heavier. The Skytee fitted onto my Vixen Hal130 tripod with an adaptor that FLO got for me. I don't have the C8 any more, but the C8/skytee setup worked very well.

Did you do much observing with the C8 on the Twilight I? If you did, what magnifications were you comfortably using and what was your impression of stability? BTW, I also struggled with connecting the slo-mo cables but eventually succeeded.

[TSRobot 158]

Hi. I tried mounting my C8 on the ESTL in daylight and immediately found that the slow motion controls were no use no matter how I tightened the tensioners so posted it back that afternoon.

[Ags 1,892]

The scope is collimated and I'm fairly happy with the low power views it gives. I just think a similar aperture mak would give more beautiful views, and be more usable on doubles. I don't know but don't think an AZ4 would be much better, and I would lose the slo-mo controls which I love. I think keeping the Newt for DSOs, and eventually get a Mak 127 for planets. Still, I'd love to hear from anyone who has tried a catadiatropic on the ES mount.

[Ags 1,892]

I think I will invest in a medium power eyepiece (like an ES 14/82) to get the best view from the newt for now. I got it mostly for looking at DSOs and it does the job well (wide angle of view and good light grasp), but I am lacking a medium power EP so I often use more mag (and wobbles) than I need. For high-mag and doubles viewing this year I have a nice little skymax 102. In time for Mars 2020 I will upgrade that to either a Skymax 127 or (if I win a lottery or two) a OMC140. Not sure if I want to be an OOUK customer, but the OMC140 combines light weight with the biggest practical Mak aperture for me. I am pretty sure the mount can cope with 3.5kgs and a short tube.

One thing I REALLY don't like about the OMC140 is the basic version is sold as 1/4PV. According to my understanding, Maks are easy to manufacture to far better quality than that; 1/4PV actually sounds a bit like a dud...

[John 31,439]

I had a play with a Twilight I clone at an astro show recently. It would be OK for a small refractor (eg: 102 F/5) but it did not seem stable to me for a larger scope.

I've used an AZ-4 with a Skywatcher 6" F/5 newt on board and my old Intes 6" F/5.9 mak-newt (10 kg OTA) on board and the mount (steel legged version) handled the scopes pretty well.

Maybe the ES version is better than the clone that I played with

 

Edited November 8, 2017 by John

[Ags 1,892]

I guess your observation applies to the ES mount too, as usually the clone and the branded original come from the same production line.

Did the clone you were looking at have steel legs like the ES does?

I've mailed ES tech support, will see what they say. The mount claims a max load of 18lbs, but I see no evidence of that.

Other ideas to improve damping time: sand in legs? Wooden tripod?

Edited November 9, 2017 by Ags

[Ags 1,892]

ES tech support have been very helpful and suggest the problem could be that there is play in the altitude joint (which I actually spotted yesterday). They suggest tightening it in quarter turn steps. I'm quite hopeful this will have some positive results!

Edited November 9, 2017 by Ags

[John 31,439]

12 hours ago, Ags said:

I guess your observation applies to the ES mount too, as usually the clone and the branded original come from the same production line.

Did the clone you were looking at have steel legs like the ES does?

I've mailed ES tech support, will see what they say. The mount claims a max load of 18lbs, but I see no evidence of that.

Other ideas to improve damping time: sand in legs? Wooden tripod?

This was the mount that I had a look at:

https://www.365astronomy.com/365Astronomy-AZ5-Versatile-Vari-angle-Micro-Motion-Alt-Azimuth-Telescope-Mount-with-Stainless-Steel-Tripod.html

 

[Ags 1,892]

Looks exactly the same, although I paid a bit extra for the ES logo :). I see TS sell it under their brand too. I'll update the thread (hopefully tonight) with my results from tightening the alt axis. I earlier had to tighten the az axis, so I don't know why I didn't think of doing this sooner.

Edited November 10, 2017 by Ags

[Ags 1,892]

I took off the dovetail head and tightened the bolt by half a turn. I tested on a random star peeping through the clouds and I see a distinct improvement. For a start I can see what I am doing when focusing at 80x and 115x and the amplitude of wobbles seemed much less. 

Could I break anything by going another half turn on the bolt? The alt axis is a bit stiffer now but not a problem.

[Ben the Ignorant 1,008]

Hi, Ags.

This might help: 

The max load for that kind of AZ mount is for an unbalanced load. My AZ-4 is supposed to take no more than 6 kilos but the motions are actually smoother now that the load has increased to almost 8 kilos, because it is balanced. Tightening the bolts makes the motion stiffer, as you noticed, that's no solution. The tripod has been made more stable with nearly 3 kilos of gravel poured inside the legs, no worry about a center of mass standing too high.

[Ags 1,892]

That's very interesting. The level of sticktion I now get seems to be OK for the long tube of the 150PDS, but I think if I go any tighter it might be an issue for my lovely little Mak 102 - I'll simply have no leverage to overcome the resistance.

[Ags 1,892]

ES tech support said to go tighter so I went a further one third turn on the bolt. The alt axis is smooth and easy with the leverage of the long tube of the 150PDS, but aiming the short tube of the Skymax 102 is not so easy, I certainly wouldn't want to make it any tighter. Hopefully I will be able to have a look at the clusters in Auriga tonight which will give a good indication of how much more stable it is. My co-observer feels we are headed in the right direction after last night's trial.