Alternative focusing

Hi All,

With some sites it is difficult to get a bright enough star to focus on and when I mentioned to a mate that occasionally it can provide quite difficult especially with my 3nm filters, he was surprised that SGP does not provide a function when focusing automatically to slew to preprogrammed brighter stars, focus and then return to the subject.

Someone mentioned Target Focus to me, but, 1. I can’t find out much about it and 2. it appears to reduce the automation which is the whole point of SGP.

Are there any plans for this or is there something I have missed already?

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SGPro does both of those things… you should always prefer “on target” focus first. If that does not contain sufficient data for focus, then consider other alternatives like pausing to go to an off target guide star. One day, depending on demand, we may attempt to automate that process… SGPro has all the pieces and parts in it to do this… some things to consider like focus target on different side of meridian and junk like that.

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Thanks Ken, so how does the target focus option work, as I didn’t know anything about this option until someone mentioned to night and I found it hidden away?

Pausing focusing is an issue that Jared has agreed to fix as currently it is a PITA to abort/stop the focusing cycle

Are you referring to aborting auto focus just hanging? If so that fix is available in the current beta.

Thanks,
Jared

Hi Jared, yes indeed that is what I was referring to.

I tend not to run the betas as we get so few clear nights here that I would rather be certain that everything was OK before commencing my captures.

Good to hear that you have fixed that, thanks.

So how does Target focus work?

Ken meant pausing the sequence, not pausing auto focus.

Take a look at the section of the PDF manual that is headed “Setting Focus and Target Positions”. Set up Focus Position and Target Position. By also setting up Manual Focus Reminders, the sequence will be paused automatically when the conditions for Manual Focus Reminders are met. Currently then you have to do the following steps manually: 1) ‘Goto Focus’, 2) perform auto focus, 3) ‘Goto Target’ and 4) resume the sequence.

Bernd

That section referred to is here:http://www.mainsequencesoftware.com/Content/SGPHelp/SettingFocusandTargetPositions.html

I have never tested this, but you should be able to pause the sequence (or have SGPro auto pause it and send you a notification: http://www.mainsequencesoftware.com/Content/SGPHelp/ManualFocusingReminders.html), Click the “go to focus target” button, do your focus… and then, instead of clicking “go to target position”, right click the target you want to return to and click “Center on”. Then restart the sequence.

Another way is to use a focus offset. Pre-imaging FW preparation is needed but only the first time you use the method.
Manually focus on a star using a NB filter.Then manually focus on a star using, say, the red filter. Take maybe 3 - 5 focus runs of each to get a mean value of the focus position.
In the FW set-up, set the mean focus position for the NB as Red +/- the difference.
Repeat for each NB filter.
Then use the focus set-up option to focus only using the Red filter.
Optionally save this FW set-up - maybe in a dedicated NB SGP profile.
This may sound a bit laborious but bearing in mind NB runs are long exposure and consume the majority of frames taken for a project, it is likely that you will only need to image in NB for the whole session. not a big deal in my opinion.
Jan, UK

How does this process relates with temperature ? All measurements must be done at the exact same ambient.

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