Hello all,
I had a look at this feature request. I'd like to offer a procedure with what exists right now in Ekos, and you tell me if/how it may be improved. Then, I would propose how we may automate/improve feedback in the code.
1. Open Ekos, connect equipment, point your telescope to your preferred star or a star open cluster. Verify your CCD can capture the star(s).
2. Navigate to the Focus Module, verify the relevant CCD is selected for operation.
3. Using the "Capture image button", grab a full-field capture of the current star field. Find the optimal focus using your preferred procedure: looping manually, auto-focus... Then reset the procedure results using the Reset button in the CCD & Filter Wheel tab.
4. From there, configure the Settings tab on the lower to not select a star automatically, to not use full field and its annulus circles. Like the following picture, for instance:
You may want to keep guiding with an off-axis guider, and suspend it (eventually) with an on-axis guider.
5. Configure the Process tab on the lower left to use Gradient as detection method, whose detection may be more robust against out-of-focus stars. Like the following picture, for instance:
6. Configure the FITS View on the right to display stars and cross hairs, as well as the default stretch function. Like the following picture, for instance:
7. Using the "Capture image button", grab a full-field capture of the current star field. You should see red circles around some stars, with their HFR written on the side. Like the following picture for instance:
Note that your optical train should be at optimal focus following step 3.
8. Configure the Settings tab to use a sub-frame. The width of the sub-frame depends on your sensor and on the size of the star. Like the following picture for instance:
9. Review HFRs and choose one star to start your collimation by clicking on it in the FITS view. Depending on which progress you made on the procedure, select a star at the center or on the sides of the frame. A new sub-frame will be taken automatically with the crosshairs overlaid:
10. Write down the current focuser position in case you want to return to it later. Click the "Start framing" button, and iteratively de-focus the star on one side of the optimal focus plane by entering a different enough focuser step value in the "Desired absolute focus position" edit box and clicking the "Go to an absolute position".
This manipulation depends on your focuser hardware, but the result should be a properly visible de-focused star. Increase exposure if necessary. This is what the CCD Simulator shows, but you should get an elongated star instead:
11. Execute your collimation procedure while the Focus module is looping on the star. If the star is moving out of the subframe, you should use guiding in parallel.
12. Move the focuser on the other side of the optimal focus plane just like you did at step 10, at the opposite distance. Check and eventually adjust your collimation.
13. When satisfied, stop looping and delete the focus results. Grab a new full-frame star field and repeat from step 9 with another star, preferably on the other side of the frame.
Note the procedure does not define what a "collimation procedure" is, as this depends on your setup.
There is also no support for determining the center of the illuminated frame right now. Such information could be determined from star ellipses on the full-field frame.
-Eric