Sesto Senso install issues on SW Esprit 100

[RugbyRene]

Hi all,

I have an issue with the install of a Sesto Senso focuser on my SW Esprit 100.

I have successfully removed the fine and coarse focus knobs, selected the correct bush (the red one), tightened all grub screws and ensured the collar was tightened. Now, when I move the focus with the remaining coarse focus knob, the whole Sesto Senso unit moves!

The other issue I have, is that it feels like to focuser is not aligned properly. When I turn it, the whole unit wobbles.

Is there anyone who has experience mounting a Sesto Senso to an esprit 100? Have you encountered any issues?

Are there any tips or tricks that I should know about.

 

Regards.

 

Rene

[Yawning Angel]

I seem to recall there are some grub screws around the collar that allow it to be centered and will aid it gripping - one opposite the clamp, and one on the bottom.

It will also need a bit of fine tuning to the shaft alignment, with the grub screws on the bush, to remove the wobble

Good luck, it's a great focuser

[wornish]

I have installed the Sesto Senso on my Esprit 100 and all worked as per the instructions.  The Red bush is the correct one.

As the previous post says you need to adjust the two 90 degree grub screws as shown in Fig 5 of the installation instructions.

 

https://www.manualslib.com/manual/1499321/Primalucelab-Sesto-Senso.html?page=5#manual

Make sure the power is OFF when turning the manual focussing knob otherwise you are fighting the motor in the focusser

 

 

Edited January 8, 2020 by wornish
typo

[Adam J]

On 06/01/2020 at 09:30, RugbyRene said:

Hi all,

I have an issue with the install of a Sesto Senso focuser on my SW Esprit 100.

I have successfully removed the fine and coarse focus knobs, selected the correct bush (the red one), tightened all grub screws and ensured the collar was tightened. Now, when I move the focus with the remaining coarse focus knob, the whole Sesto Senso unit moves!

The other issue I have, is that it feels like to focuser is not aligned properly. When I turn it, the whole unit wobbles.

Is there anyone who has experience mounting a Sesto Senso to an esprit 100? Have you encountered any issues?

Are there any tips or tricks that I should know about.

 

Regards.

 

Rene

You don't attach it to the fine adjustment side you install on the course side. 

[wornish]

8 hours ago, Adam J said:

You don't attach it to the fine adjustment side you install on the course side. 

Sorry but that is incorrect.  You certainly do attach it to the fine adjustment side that is how it gives such fine control it is very clearly shown in the manual.    

When installed it takes about 95,000 steps to go from fully in to fully out.

[Adam J]

1 hour ago, wornish said:

Sorry but that is incorrect.  You certainly do attach it to the fine adjustment side that is how it gives such fine control it is very clearly shown in the manual.    

When installed it takes about 95,000 steps to go from fully in to fully out.

Ok well on my focus cube and virtually all other brands of auto focuser I can think of attach to the course side. The reason for that design choice is that for the most part they are easily accurate enough to allow you  to do this. For example on my Esprit 100 I was using a step size of 60 and I found that it took between 10 and 20 steps to make any detectable difference in focus. So attached to the course side it was giving between 10 and 20 times the required level of accuracy. 

The second reason that most makes do not place the auto focuser onto the fine adjustment is that it increases backlash, the reduction takes place via a pair or rings with ball bearings sandwiched between them and what you will notice is that even with the focuser locked down hard you can move the fine adjustment slightly (backlash) while the course side is virtually rock solid if you have the rack and pinion mesh setup correctly. Essentially it feels slightly sprung. 

So as it appears I am indeed wrong and this particular auto focuser attaches to the fine focus nob ill add that to the long list of reasons I am glad I went for the Pegasus astro focus cube instead of a SESTO SENSO, along with things like the cost of the adopters (£70) for different sized scopes and the fact that they don't include a temperature sensor and expect you to pay an additional £40 for the privilege (a temperature probe that costs maybe £2 to make).

Adam

 

 

[DaveS]

Not all focusers make connection to the coarse side easy. The two on my TS triplets have grub screws only on the fine-focus side. After a conversation with Rupert at Astrograph he recommended attaching any focuser to the fine side as otherwise it would mean removing the whole pinion shaft. Looking at the FT on my ODK12 I think it would be possible to remove the coarse knob.