SharpCap Forums

Is there a way for Sharpcap to Guide without an additional guide camera and potentially a guide scope?

I am asking before buying more hardware. I have been recruited to gather images for exoplanet research. This involves capturing images (30 second) over several hours. Alas, the target stars slowly move, even with very good polar alignment. I see in AVSO guidance, there is the possibility of image guiding that uses differences in raw images to make mount adjustments. Does Sharpcap support this? If so, how does that work?

It is raining so I cannot try the following. With only one camera and no guide scope, open one copy of Sharpcap. Connect this Sharpcap to the mount and camera. Polar align it and focus it. Tell Sharpcap this is a guide camera. Focus the cam on an appropriate alignment star. Now open a second copy of Sharpcap and accomplish the night’s objectives. Will this work?

Setting the above aside, there are tools native to Sharpcap that seem so close to autoguiding. I am thinking of feature tracking and pixel positioning for example.

Finally, Robin thanks so much for Sharpcap. I routinely am impressed with its capabilities!
Mount: SkyWatcher EQ6 pro.
Camera: ZWO ASI294.

Hi Randy,

the short answer is no - SharpCap doesn't do that sort of autoguiding for deep sky imaging, and I would normally recommend people use PHD2 for guiding as it does the job really well. In fact, that's one reason that I have never tried adding guiding of that sort into SharpCap - it would take a lot of work to even come close to matching PHD2 , so why try to duplicate it...

Anyway, since it sounds like you are just trying to prevent long term drift rather than keep the mount pixel perfect steady during exposures, there may be other things that you can try. For instance...

SharpCap can use plate solving to recenter the image on the desired location, so you could use this from time to time (maybe every 15 to 60 minutes - depending on the drift rate) to bring things back to the correct location. This could be arranged using the advanced sequence editor (capture 30 frames, recenter using plate solving, repeat...)

You can also (mis) use the live stacking feature in SharpCap - although you are not really interested in the live stacked image, it can be set up to save the unprocessed frames from the camera while stacking, so effectively equivalent to capturing. The advantage of the live stacking approach is that the recenter with plate solving is built in and can be set to trigger when the image has drifted by an adjustable number of pixels - see the guiding tab of live stacking where you have a 'Recenter' option on the right.

The down side to these approaches is that you will be losing observations during the recentering time, which might mean you lose a minute every 30 minutes or so.

hope this helps,

Robin

Hello Randy,

I know only one case where you can connect 2 software to 1 camera.
So the normal use is: one camera connected to one software.
It is different if you have 2 cameras ... then you can start SharpCap 2 times and each SharpCap connects to one camera.

For the guiding ... it depends how much the stars will drift during your observation session. And it depends on the field of view on your detector.
(Note that it is not only coming from a poor polar alignment ... you have other contributors ... air refraction, mount tracking rate, material bending.)

For example you have an APC detector and the star shift is 5% to 10% of the detector surface, then you can maybe set a ROI and write a script that move the ROI centred back on the stars field. The stars position on the image is calculated with a plate solve.
In this case ... the mount is continuously drifting out ... the centring is only done with the position of the ROI.

With some mount training ... it could be possible to perform a simple guiding by doing a short movement of the mount in the RA/DEC axis (with very low rate).

Regards,
Jean-Francois

In the case that you have a QHY camera (in place of the ZWO), you can do the connection of one camera with two software using the Broadcast WDM driver of the QHY camera. I did it between SharpCap and PHD2 with only one camera.