Fast forward to end of 2020....just received by Esprit120, and with a 3.5kg imaging setup, there’s slipping with the fine focusing knob.
If scope is pointing up to the sky, fine knob ‘looses’ some turns and is unable to rack back the focuser. I discovered it as the Sesto Senso was not smoothly racking back the focuser.
The coarse knobs work perfectly, so adjusting those 4 tension screws is what fixes the fine knob problem? It seems strange as they probably are for the overall focuser, and I need to adjust only the fine focusing.
Disassembling the fine/coarse knob, I see the ball bearings, and if I turn the fine knob, when it looses rounds I can see the ball bearings move but they don’t “grip” enough so they don’t turn always the focuser if vertical, but they roll.
I tried adjusting the grub screw that is immediately near the knobs (not part of the four screws holding the scope base), it affects somehow the fine focusing knob but it justl slips, there’s no right setting achievable. It works if scope is not vertical.
I posted also on SGL with a picture (cannot upload here as image is too big), any idea?
I have just received a Primaluce Lab Sesto Senso 2 Focuser. It didn't work out for me (using an Esprit 100) and I'm returning it to get a Pegasus Dual Motor Focus Controller DMFC and two Pegasus Motor Focus Kit V2 (universal and SCT).
- Senso ASCOM driver doesn't show the temperature correctly like the Windows App does;
- Senso ASCOM driver doesn't seem to work well with APT and it crashes it frequently;
- Senso cannot prevent the focuser slipping back over time when pointing at Zenith;
- Senso presets are worthless IMHO as they cannot be relied upon;
- Increasing the current can help (but not solve) the slipping but some users have had the units fail as a result (just when the warranty has run out too);
- Senso doesn't have a gearbox e.g. no 120:1 gearing which brakes the focuser (improves it);
- Senso uses micro-steps. Each micro-step reduces holding torque e.g. much less braking with 2 or 4, almost none with 16-64!
- Senso counts steps but the position will not be exact and slips back towards the Zenith;
I was attracted the Primaluce Lab Senso because it "looks nice" and doesn't need a bracket to hold it in place. It should "work", but my limited experience it falls too far short of what is required...
I noticed that the Senso counts pulses but can't be guaranteed to reach the actual distance. It doesn't have any "backlash" because it's directly coupled but if it doesn't reach the required destination then it very much "misses the target" and the presets cannot be relied upon. Over time it will slip back and require recalibration. The software provides for this (as a fix up IMHO).
The Senso Windows Application has some "quirks" e.g. the Up and Down buttons won't always respond but putting a value and clicking move will respond. Saving Presets doesn't always work.
The Senso with ASCOM the driver doesn't correctly report temperatures e.g. it always shows a fixed (negative) temperature even indoors at 20 C.
Perhaps by V3 or V4, Primaluce will have the opportunity to resolve some of these issues. IT is worth noting that the Senso doesn't use a gearbox. The cost of a gearbox can be greater than a Servo Motor but it is perhaps a false economy not to use one.
NB the Pegasus Motor Controller uses a 1:120 gearbox. The motor provides tension even when switched off that increases 1:120 and prevents rotation. The Senso uses a current to hold current position. When pointed at the Zenith it can slip back so focus points are NOT consistent.
One other difference is the Pegasus Motor Controller can be used with several motors. It attaches to the Mini Focuser and not to the Micro Focuser. The Senso uses the 10:1 Mini/Micro gearing of the focuser so using it manually offers some resistance but far less than a gearbox can. The Pegasus Motor Controller provides 10:1 and 1:1 rotary control (what you want) or the shaft can be completely decoupled for complete manual operation. It is also possible to use the Pegasus Motor Controller with many other motors e.g. a Lakeside unit.
There is also a Pegasus "all in one" Focus Cube V2. It has the same motor and gearbox as the Motor Focus Kit and can easily lift 6kg when pointed at the Zenith which is an increase on the V1 (4+ kg advertised). This can be a good solution for a one scope setup, but for more than one scope it makes sense to share a Motor Controller. The manual rotary control is a separate box with Focus Cube but integrated with the DMFC.
Edited by SimonMiller, 25 November 2020 - 09:02 AM.