Focus target feature request

Sequence Generator Feature Requests
1

The focus target feature of SGP is not one that sees much light of day. I wondered if it could be made more useful if it linked with the AF settings. In the AF settings, there would be a checkbox to use the focus target and, providing the coordinates were populated and safe, it would slew off, focus and then return to the image coordinates.

It might help those who are imaging large galaxies, bright nebula or clusters.

2

We have considered this in the past. It generally gets pushed because of the “what if” scenarios:

  1. what if your focus target has set?
  2. what if your focus target would cause a meridian flip?
  3. would auto centering also be needed to get to your focus target (seems excessive), but would certainly want to be triggered to get back on target.

I think if we were to implement something like that the idea would be that the focus target needed to be very near your actual target.

Jared

3

What about having SGP, on selecting the option, just move a short distance to the East of the imaging target before AF. I would think that in most cases that would clear the large object out of the FOV and keep the focus target in the vicinity of the imaging target.

4

yes - there are always gotchas. The following suggestion by Larry might be easier - a simple slew, say in DEC of a few degrees towards DEC=45 might bypass meridian flip and altitude problems.

5

Being able to use the focus target would solve focusing issues in many cases but, as Jared pointed out, it has some side effects – the biggest is probably accidentally triggering a meridian flip. Moving only in DEC does not completely solve the problem since the target could track across the meridian during the auto focus run and the return slew to target would cause a meridian flip. With a more complex check, the slew to the focus position could simply trigger a delay to wait for the meridian crossing to happen first. Of course, both the target and focus target would have to cross. Since this would be a rare occurrence, the impact would be minimal.

I would suggest that using the focus target option makes it become the target coordinates used for slewing and centering. Once focusing / centering is done, a short slew to the real target coordinates should be accurate enough.

I would also like to see the focus target be a Simbad lookup, so that a reference star could be picked as the focus target rather than just guessing at some coordinates to use.

Charlie