Hi All,
I've refactored the Build Filter Offsets Utility introduced in 3.6.5
Recap: What's are Filter Offsets?
There are 3 ways to Autofocus in Ekos. Here, I've setup an example that covers each:
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1. Use Autofocus on the designated filter. In the example, Lum is configured like this. Whenever the Lum filter is selected in a sequence, Autofocus will be run on Lum.
2. Use Autofocus on a "lock" filter. In the example, Sii, Ha and Oiii are configured like this. Whenever Sii, Ha or Oiii are selected in a sequence, Autofocus will be run on Lum. When Autofocus completes (for example at 37273), Focus will apply the offset to go from Lum to, for example, Ha (in this case (-23 - 0) = -23 ticks. The focuser moves to 37273 - 23 = 37250 and Ha will again be selected in the filter wheel. This is useful in the case that its either difficult to focus a filter or it takes a long time because the exposure needed is long.
3. Don't use Autofocus but apply offsets on filter change. Red, Green and Blue have been setup like this. For example, when swapping from Red to Green, no Autofocus will be run and the focuser will from its current position (e.g. 37118) by the offset different between Red and Green. In this case, 4 - (-21) = 25 ticks. So the focuser moves to 37118 + 25 = 37143 and Green will be selected in the filter wheel. This can be useful to reduce the number of Autofocus runs in order to spend more time imaging and less time focusing.
So how do I setup Filter Offsets?
You can do it manually by running Autofocus several times and getting an average focus position for each filter. Then do the maths yourself to work out the offsets and enter these numbers into the Offsets column in the Filter Settings popup.
3.6.5 Introduced the Build Filter Offsets utility, launched from the Filter Settings popup by pressing the Build Offsets button. This helps to automate the process. See the Build Offsets section in the Focus section of the
Kstars Handbook
Latest Build Filter Offsets
The utility has been refactored and some bugs fixed. In addition, now the utility takes advantage of Adaptive Focus. The reason for this is that running the utility on, for example, 7 filters with 5 Autofocus runs per filter will probably take longer than an hour. In this case, the environment factors that affect Focus such as temperature start coming into play. So, if you have already configured Adaptive Focus then this will be used to adjust each focus run for the environmental conditions in the first run in the utility to allow for better comparison of Autofocus results (an essential step in calculating Filter Offsets).
In this example, I've run Build Filter Offsets on all filters:
Here, the Adapt Focus box is checked and the results are adapted for temperature changes (I have this configured as 10 ticks per degree centigrade).
In order to help see what's happened, hover the mouse over an Autofocus result and an Adaptive Focus Explainer toolti[p will appear...
It shows the measured Autofocus result for that run (17994), adaptations for Temperature (0.3C change equal to 3 ticks) and Altitude (-1.6 degrees Alt but because I have configured 0 ticks per degree Alt, the Alt adaptation is zero). The deltas are between this AF run and the first one. Then it shows the resultant, adapted Autofocus result (17997). The Adapt Focus box can be toggled on and off and the grid will show the appropriate values which can then be saved into Filter Settings for future use.
In addition, the reference filter can be changed. It defaults to the first row and is indicated by an "*". In this case "Lum *". This can now be changed by double clicking another filter.
The code has just been merged (today) so is available to anyone interested in taking bleeding edge or daily updates. It will be in the next official Kstars/Ekos release.