SGPro, FocusLock and Lodestar with OAG

[sloz1664]

As SGPro are actively promoting the FocusLock focussing system from Optec Optical & Electrical Products. I was wondering if anyone is actively using this system. Preferably with a Lodestar or LodestarX2 and OAG, using the Lacerta kit.

Steve

[swag72]

I saw this Steve and thought that in theory it sounds like a great idea..... I'm starting to get stuff together to give it a go next year ?

[Lars]

I looked at Optec's web page but didn't find much information about the hardware used in the Lacerta for Lodestar hardware kit other than it works in a similar way  as with an ONAG. I can see in the picture they show of the Lodestar X2 camera that they seem to have replaced the front window but not more info than that. I may have missed it but is there any more info on the hardware used?

Regards

Lars

[RayD]

3 minutes ago, Lars said:

I looked at Optec's web page but didn't find much information about the hardware used in the Lacerta for Lodestar hardware kit other than it works in a similar way  as with an ONAG. I can see in the picture they show of the Lodestar X2 camera that they seem to have replaced the front window but not more info than that. I may have missed it but is there any more info on the hardware used?

Regards

Lars

PDF showing the kit contents here

[Lars]

Thanks Ray.

Regards

/Lars

[iansmith]

Hello,

I know how this works with respect to the ONAG guider and it works very well. It keeps my Edge 11 in focus throughout an imaging session. With the ONAG I use a Starllight Xpress Ultrastar (which you really need as you only get the IR light with the ONAG). As an OAG captures all the light from a guide star you should be able to use a X2 Lodestar. I don't know how they've made this work with the OAG. The ONAG relies on the astigmatism introduced by the cold mirror of the ONAG and the way it varies as you move in and out of focus (see https://www.innovationsforesight.com/education/real-time-autofocus/ for more on that). 

I'm guessing that the tilt window used in the Lacerta system introduces a similar astigmatism. This doesn't affect guiding performance with the ONAG and I assume it wouldn't with an OAG. Because the focusing is continuous, once focus has been achieved, the focuser (a Moonlite  focuser in my case) is moved in small steps as necessary. The steps are small enough that imaging is not disturbed, although I guess this would rely on how tightly you have connected everything.

The main thing you will need to do is to make sure that your OAG and imaging camera are parfocal, so that when the FocusLock s/w thinks the OAG image is focused then so is your imaging camera. I did this with the help of a Batinov mask.

The Optec software is easy enough to use, but as far as I know it requires PHD2 to work. It grabs a copy of the guide star image from PHD2 to anaylse to see if the focus needs to be changed. It will average several images before making a measurement so variations in seeing are ignored. You can set the number of frames to average. There is a simple calibration process to go through and there is an option for backlash compensation should you need it. If you have filters that aren't parfocal then you can provide offfsets to the software to handle this.

Hope this helps.

Cheers, Ian