Backlash ¿ Applied or Not Applied ?

[Real14]

Hi,

Maybe it is just me that I think that the defined backlash of my focuser is not applied when changing direction.

I have a ZWO EAF.

How can I check if either the ASCOM driver of ZWO is faulty or SharpCap is not applying the Backlash ?

Thank You for any tips

regards Rainer

[admin]

Hi,

Ascom doesn't actually make focuser backlash available to applications like SharpCap – if there is backlash compensation inside the Ascom driver then there is no way for SharpCap to find out about it or to turn it on or off. The only thing SharpCap can do is ask the focuser to move to a particular position.

Note that is my understanding that if you do have backlash compensation turned on then the adjustments made to the focuser position by the backlash compensation are not visible in the value displayed in SharpCap. For instance if you have a backlash compensation value of 20 and you start at position 10,000 and then move to position 10,050 and then move inwards five units, the display will show 10,045 even though the driver may well have actually moved the focuser to position 10,025.

Coincidentally, I was writing backlash compensation code yesterday that will allow SharpCap to implement its own backlash compensation if you are Ascom driver doesn't support it. This will be in SharpCap 3.3

Thanks, Robin

[Real14]

Hi,

Ascom doesn't actually make focuser backlash available to applications like SharpCap – if there is backlash compensation inside the Ascom driver then there is no way for SharpCap to find out about it or to turn it on or off. The only thing SharpCap can do is ask the focuser to move to a particular position.

Note that is my understanding that if you do have backlash compensation turned on then the adjustments made to the focuser position by the backlash compensation are not visible in the value displayed in SharpCap. For instance if you have a backlash compensation value of 20 and you start at position 10,000 and then move to position 10,050 and then move inwards five units, the display will show 10,045 even though the driver may well have actually moved the focuser to position 10,025.

Coincidentally, I was writing backlash compensation code yesterday that will allow SharpCap to implement its own backlash compensation if you are Ascom driver doesn't support it. This will be in SharpCap 3.3

Thanks, Robin

Hi Robin,

Thanks for the information. I thought that setting backlash in the setup menu of the ZWO EAF focuser would be available to the ASCOM application.

I will need to check if the little menu of ZWO EAF focuser does apply the backlash. I will do this by using their ASI Studio application.

This is intersting as I guess from focusers there are maximum of 5 with no backlash. Backlash is a common problem in focusers, IMHO

[Real14]

Hi,

Ascom doesn't actually make focuser backlash available to applications like SharpCap – if there is backlash compensation inside the Ascom driver then there is no way for SharpCap to find out about it or to turn it on or off. The only thing SharpCap can do is ask the focuser to move to a particular position.

Note that is my understanding that if you do have backlash compensation turned on then the adjustments made to the focuser position by the backlash compensation are not visible in the value displayed in SharpCap. For instance if you have a backlash compensation value of 20 and you start at position 10,000 and then move to position 10,050 and then move inwards five units, the display will show 10,045 even though the driver may well have actually moved the focuser to position 10,025.

Coincidentally, I was writing backlash compensation code yesterday that will allow SharpCap to implement its own backlash compensation if you are Ascom driver doesn't support it. This will be in SharpCap 3.3

Thanks, Robin

Hi Robin,

Any news about the integrated Backlash feature you are talking about here ?

Thanks Rainer

[admin]

Hi,

yes, I have this working in SharpCap 3.3 now. There are three modes

No compensation
SharpCap handles the compensation
Ascom handles the compensation

unfortunately the user has selected the correct mode as there is no way to find out from an Ascom driver if it is handling backlash compensation.

Cheers, Robin

[Real14]

Hi,

yes, I have this working in SharpCap 3.3 now. There are three modes

No compensation
SharpCap handles the compensation
Ascom handles the compensation

unfortunately the user has selected the correct mode as there is no way to find out from an Ascom driver if it is handling backlash compensation.

Cheers, Robin

Hi Robin,

Thank You. Where do I find SharCap v3.3 ?

regards Rainer

[chongo228]

I have the ZWO eaf and I can confirm that the backlash compensation does work when set under the advanced menu.

To test it I put the backlash at a very high number....in this case 200 (anything over that would cause problems and the number would reset to a lower value when I opened the menu back up....200 seemed to be the highest I could go). When I changed directions the focuser took noticeably longer to move than when I had the backlash set to 0,5 or my normal setting of 25 while imaging. However there have been some nights that I'm pretty sure it stops working and magically gets set back to 0 in the settings....I'm not sure how or why this happens. I think controlling it in SC with 3.3 will be easier and a stability improvement.

As stated above SC can't see the backlash. When I had backlash set to 200 and changed directions with +5 clicks the position would only change 5 digits even tough it had moved 205 clicks.

[admin]

Just to confirm that in SharpCap 3.3 when you have enabled backlash compensation in SharpCap, you won't see the effect of it in the focus position readout. For instance if you set are compensation value of 100 and move the focuser -5 from 19900, the value will read 18995 in SharpCap. If you have a separate application your focuser that shows the value, you will likely see it there reading as 18895.

Cheers, Robin

[Real14]

Just to confirm that in SharpCap 3.3 when you have enabled backlash compensation in SharpCap, you won't see the effect of it in the focus position readout. For instance if you set are compensation value of 100 and move the focuser -5 from 19900, the value will read 18995 in SharpCap. If you have a separate application your focuser that shows the value, you will likely see it there reading as 18895.

Cheers, Robin

Thank you chongo228 and Robin.

Is version 3.3 already available or is it in preparation ?

regards Rainer

[admin]

Hi,

still in closed group testing for maybe another month or so before I open it to a wider audience for testing.

Cheers, Robin