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Autoguiding through guide scope

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My current setup is composed of a DLSR on a TAL 200k primary scope on EQ6 mount. Attached to the primary scope, a SVBONY 60mm guider with a ZWO 120 mini camera which I intend to use for autoguiding.
My question is: is it essential to have the guider perfectly parallel with the primary scope or can Ekos take care somehow of a possible little offset? Can somebody help me understand what is the difference between plate solving and autoguiding in this context?

Thank you,
2 years 1 month ago #81953

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Plate solving is a way to determine the exact RA/Dec coordinates of your scope: take an image, detect stars, compare stars to a giant index file of known star positions.
Autoguiding does not depend on knowing the scope's exact position. The guide camera takes a series of short images while the main imaging camera is taking a much longer exposure. Detect stars, choose a "guide star", determine for each short guide exposure if the guide star has moved. If yes, issue a small correction pulse to the mount to (hopefully) move the guide star back to the original position. Guiding allows longer main camera exposures by correcting tracking errors of the mount.

The guide camera does not need to be pointed at exactly the same place in the sky as the main camera - unless you need to use the guide camera for positioning/framing for some reason. For example, if your dslr is not connected to Ekos (say you are controlling your dslr only with an intervalometer and storing the images on the camera's SD card). In that case, you would want to spend a bit of time making the center of the guide cam field of view = center of main cam field of view.
The following user(s) said Thank You: Albert Tamayo, Cristian
2 years 1 month ago #81958

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My understanding is that the guide scope and the main scope do not need to be perfectly aligned for you to be able to do autoguiding. However you don't want them pointed off in significantly different directions because it can cause some field rotation to occur.

Autoguiding is done through the guide scope and uses one or multiple stars to allow you to track your target. Plate solving is done through your main scope to allow you to center the main scope on your target for imaging.

Having said that, I usually do my polar alignment with my guide scope and the polar alignment tool uses plate solving to as part of the process. If you do this then you need to make sure you have the correct scope and plate solve capture options selected in the Ekos Align tab. For me that means:
  1. Go to Align tool in Ekos
  2. Make sure your Guide scope is selected in the scope selector drop down and the correct FL is indicated.
  3. Select your Guide scope camera in the CCD drop down and the correct FOV is indicated.
  4. Go to the Polar Alignment tab in the Align tool and do your polar alignment with the guide scope.
  5. Once polar alignment is complete then switch the scope selector to you main scope and the CCD selector to your main imager and select the Solution Results tab.
  6. Now you're ready to use plate solving with your main scope to set up your imaging session. There are several ways to do this.
  7. Once you have your target framed then you can start autoguiding using your guide scope in the Ekos Guide tool.

Being forgetful and not making sure the right scope and CCD combination are selected in the Align tool is a common mistake I make. If my polar alignment fails or plate solving fails that's always the first thing I check.
The following user(s) said Thank You: Albert Tamayo, Cristian, Bill
2 years 1 month ago #81959

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