How to shoot while automatically tracking the planet

Discussions of using SharpCap for Planetary Imaging
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japwilkos
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How to shoot while automatically tracking the planet

Post by japwilkos »

When shooting a planet while guiding with sharpCap, do I need a guiding scope and camera in addition to the imaging camera like DSO imaging?
Also, can SharpCap operate two cameras at once?
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Re: How to shoot while automatically tracking the planet

Post by admin »

Hi,

SharpCap can only run one camera at a time – if you want to run more than one camera then just run more than one copy of SharpCap.

If your normal mounts tracking is having trouble keeping the planet in view then you can certainly try using the feature tracking option in SharpCap to send guiding commands to the mount. This uses the same camera that is being used for imaging.

Cheers, Robin
japwilkos
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Re: How to shoot while automatically tracking the planet

Post by japwilkos »

Hi Robin,

I tried to run feature tracking, but the calibration failed and did not lead to guiding.
Also, even if I press the monitor button, I cannot even calibrate with an error unless I raise the gain considerably until it becomes full of noise.

By the way, the camera I'm using is QHY 5III462C .
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Re: How to shoot while automatically tracking the planet

Post by admin »

Hi,

I must admit that the feature tracking has never been the most successful part of SharpCap. There are some tweaks in SharpCap 3.3 that might make it more usable – firstly it has a mode where it doesn't look for image features but instead tracks the centre of brightness of the image. If you're imaging a planet and it's all in view then that should be perfectly good enough, although it would work for tracking a close in view of lunar craters for instance. The second improvement is that it can track using the camera ROI rather than the mount – that's probably more useful for people with larger imaging sensors than the 462.

Cheers, Robin
japwilkos
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Re: How to shoot while automatically tracking the planet

Post by japwilkos »

Hi Robin,

thank you for your answer.

Until recently, I used to use FireCapture a lot. This is because FireCapture has a very good auto-guiding function.
However, after changing the camera to 462C, I switched to SharpCap because there were uncorrectable problems such as a mosaic pattern appearing on the capture screen and the white balance being significantly out of order.

Auto-guiding with FireCapture is very easy, requires no calibration, is intuitive and easy to use polar settings to keep the planet in the FOV for hours. Moreover, there is no need for a guiding scope and a guiding camera.
It seems that planetary imaging with SharpCap requires a guiding scope and a guiding camera, which I need to control with an application such as PHD guiding.
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Re: How to shoot while automatically tracking the planet

Post by admin »

Hi,

I must admit I can't see how you could do auto guiding that drives the mount movement without some sort of calibration – if the planet is too far to the right in the image for example how does the application know which way to move the mount in order to get it back in the centre without some sort of initial calibration to determine how movement of the mount corresponds to movement of the planet in the field of view (effectively allowing the application to work out rotation of the camera, scale and any image flip due to secondary mirrors).

I'll have to look into that a bit further – maybe there's a clever way to avoid all of that…

Cheers, Robin
japwilkos
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Re: How to shoot while automatically tracking the planet

Post by japwilkos »

Hello Robin,

Certainly, FireCapture's auto-guiding function is strange in a sense. It is possible to guide only by the specifications of the camera that automatically recognizes without inputting the focal length of the telescope to shoot.
Unfortunately, I don't know how it works.

My telescope has a combined focal length of 6000mm, a camera pixel size of 3.75μ, and a sensor size of 4.8mm x 3.6mm.
Can SharpCap calibration be successful and guide with this equipment?
Also, it seems that calibration cannot be performed if the brightness of the image of the planet is low. If the gain is raised too much, the brightness of the planet surface will be saturated and the image will be corrupted and image processing will fail. If you can't guide without increasing the brightness, the purpose of shooting will be lost.

This problem is not easy.

cheers
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Re: How to shoot while automatically tracking the planet

Post by admin »

Hi,

I've never tried such a long focal length – however my best suggestions would be to try the following:

* Try SharpCap 3.3 and use the 'Centre of mass' option for tracking instead of 'Image features'.

* Use the 'Guiding Rate' option for the mount speed – this would use the pulse guide functionality which should suffer much less from backlash, which should make the calibration more likely to succeed.

* If the mount doesn't support pulse guiding, SharpCap supports ST4 guiding on certain brands of camera – connect the ST4 cable from the camera to the mount and choose 'On Camera ST4' in the SharpCap hardware list.

Cheers, Robin
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