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IDProjectCategoryView StatusLast Update
0002250CCdcielGeneralpublic19-12-27 18:43
ReporterThomas Jaeger Assigned ToPatrick Chevalley  
PrioritynoneSeverityfeatureReproducibilityN/A
Status acknowledgedResolutionopen 
Product Version0.9 
Target Version2.0 
Summary0002250: More Cameras on one mount - CCDCiel instances with dither synchronization
DescriptionIn search for new exciting features "Multi Camera Dither" would be one for the far future of development.

Fancy we have two scopes and cameras on one mount, for example the main scope is imaging a nebula and a second camera with a telephoto lens images a widefield view piggyback.
Another example, someone has to equal scopes on his mount and a mono and a colorcamera attached simultaneously.

Starting one instance of CCDCiel with a master option and further instances as slaves. Only the master manages guiding, planetarium and mount. Before the master dithers the new image it wait for all slaves to finish their frames.

This is not a feature request that I need, it simply would be a development target.

Thomas

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Patrick Chevalley

19-12-26 10:30

administrator   ~0006167

Thank you Thomas to open this subject here.
There is already a few discussion on the mail list but it is more likely I forget about them.

The idea is to have one master instance of CCDciel to manage one camera, the mount, autoguiding, dome, ... as a with a single instance.
Then we can add any number of slave instance that only manage a camera with it's focuser and filter wheel. This slave can run on the same or another computer.

For now I will suppose we loaded a compatible sequence, with plan of the same duration, on the master and each slave. When the sequence is started on the master it move the telescope to the target and then order the slave to start the plan.

All the problem is the level of synchronization we want between this instances.
At first it look good the main instance do not dither or slew to another target when the other camera are doing an exposure.

But this synchronization can make a lot of observing time to be lost, just waiting for the other camera to complete the exposure.
For example, doing 10 minutes exposure and a slave start an exposure just 15 seconds before the master want to dither make a loss of 10 minutes on the master.

A more intelligent synchronization can be done if the master can estimate the time the next mount movement is due, send this time to the slave that can now evaluate if it is worth to start the exposure or wait.
In the previous example this just make the slave to wait 15 second more before the dither.

But even with this method up to half the exposure time can be lost at each mount movement.

This make the synchronization probably good only when using short exposure and fortunately the camera that require frequent dither also work best with short exposure.

When using long exposure and camera that not require dither it is simpler to not bother with synchronization and just trash one exposure per night on the slave when the meridian flip is done, as explained here:
https://www.swagastro.com/dual-imaging-set-up.html and https://www.swagastro.com/latest-dual-rig-adventure.html
This method can already be used with the current version of CCDciel.

Thomas Jaeger

19-12-27 18:43

reporter   ~0006173

I agree, it is more a thing of the future, because it is not easy to implement
for you and not easy to understand for the user.

Sara Wagers way not to dither is not good. Dither brings more than
making more frames.

In rare cases mostly on astro vacancies under perfekt skies I use two DSLR cameras on one
mount. Doing this I use APT-Tool from Ivo Stoynov (Bulgaria). APT is
one capture programm which masters multi camera control and dithering.
Unfortunately Windows only.

I saw that you took this topic on the roadmap. Try APT multi camera
control on night to understand it is working here.

For me, a progress in CCDCiel would be

1. Better star capture in focusing. If I see a star clearly on the
screen, than it should be captured.

2. 0001880 Show "time elapsed" and "estimated.."

3. 0001894 Sequence editing while running

Issue History

Date Modified Username Field Change
19-12-25 22:54 Thomas Jaeger New Issue
19-12-26 10:30 Patrick Chevalley Assigned To => Patrick Chevalley
19-12-26 10:30 Patrick Chevalley Status new => acknowledged
19-12-26 10:30 Patrick Chevalley Target Version => 2.0
19-12-26 10:30 Patrick Chevalley Note Added: 0006167
19-12-27 18:43 Thomas Jaeger Note Added: 0006173