Advice needed for skywatcher Esprit/Sesto senso v2 set up

[RigelB]

Hope I am in the correct forum area for this as this is my first post but any advice would be welcome.

I am struggling with Sesto senso v2 attached to the micro focusser of my Esprit 120mm refractor. I have the skywatcher field flattner, Starlight Xpress 7 position filter wheel and OAG, Starlight Xpress Trius 694mono attached so not that heavy.

At any reasonable telescope angle e.g. 60 degrees the focus point in the software is anything but repeatable but the focus point on the draw tube is roughly the same.

The electronic focusser is fitted correctly and calibrated. The focus holds no problem but one night focus is at say 93000 and another 47000. this is stopping me trying autofocus in SGPpro.

So, I think the problem is the fact the Sesto senso attaches to the micro focusser and it is slipping.

I have tensioned the micro focusser screw/untightened the self centering clamp on the Sesto a little.

I can achieve focus with a bahtinov mask but I really want auto focus.

Are there tensioner screws I should adjust on the skywatcher focusser?

Is this never going to work without a better focusser e.g. a starlight instrument replacment focusser or the Primaluce Essato?

Should I have gone with the Pegasus Focusser which attaches to the coarse focus knob?

[Big Jim Slade]

The focuser on the Esprit is pretty bomb proof. I have a Lakeside stepper attached and it has no problems with slippage, even at the zenith with something over 2.5 kilos of imaging kit hanging off it. I've never had to tweak it.

I'd leave the scope focuser out of you equation for now and focus on getting the Senso as firmly attached as possible. Hopefully someone with some experience there can chime in.

[newbie alert]

I'm not using the same equipment but I use a moonlite on a esprit 80 with a atik and starlight xpress  fw.. in the moonlight software I have to set the furthest point inwards to NULL, otherwise I had issues like you have with different figures.. I'm sure if it is slipping that would also cause the same issues

Hope you rectify the issue

[rpineau]

I installed a Sesto Senso 2 on a William Optics GT81 .. and at first I had slippage issue too.

I had to re-tighten every set screw to solve the issue. I also increase the amount of current to the motor in the Sesto Senso 2 config (I actually use my own X2 plugin in TheSkyX Pro and have an option to do that, not sure the current software from Primaluce Labs does it too, may be on the user 1,2 and 3 settings).

I'm honestly not impressed by the Sesto Senso 2 .. it seems a bit weak on torque and tend to slip. With my new setting and very tight set screw it seems better. As said above, the focuser itself is find and rock solid so In really suspect the Sesto Senso 2 to be the issue there as a move to and from 2 positions was not always ending up in the same place ... sometimes by a lot.

I would say that the default setting on the Sesto Senso 2 are not the best and using the "Slow" setting is you best bet a this point or set your own custom settings.

I set the speed to 7 and the current to 8 on all 3 values (acc, run and dec) and the hold current to 1 (usually once the destination is reached it doesn't move). This seems to give me a good speed with decent torque. If I see more issue I will reduce the speed but leave the current at 8, this will increase the torque and assuming there is not more slippage in the set screws and different connections ... it should be accurate.

Rodolphe

[rpineau]

So I did more test  as there was still some slippage... BUT ... it was not in the Sesto Senso coupling

Turns out that it's inside the 10:1 knob assembly of my WO GT81 IV. I was able to reproduce the slippage without the Sesto Senso 2 on it. This probably means they are using some clutch system to couple the 1/10 know to the main one and that's where the slippage happens. I know this doesn't happen on my Feather Touch on another telescope. Ao you might see a similar issue on yours.