Full solar disc feature tracking and RAM DISC advice

[AstroMathmo]

Hi All

I'm making good progress doing solar imaging with SCPRO 4. Right now I am doing some full disc work and want to see how low I can take the ROI to max out the frame rate, or equivalently use the highest focal length I can. Either way I am trying to image the entire disc with minimal margin.

Does anyone know how to set feature tracking optimally to keep the disc well centred? I have to set up and take down every time and doing daytime PA is a bit rough and ready, despite marking where my tri-pier feet go, so I have some inevitable slow drift that I'd like to kill, especially when I'm leaving it unattended, maybe on a seeing trigger. Note that I know how to centre in post processing. It's doing it at the capture stage that I want to sort out. My mount, a CEM70G is connected to SCPRO fine and I can recenter with the internal controls manually OK.

I'd also like to try using a RAM disk with Sharpcap. Ideas as to which works well with SCPRO under Windows 11 Pro? I've tried ImDisk and it usually trashes out with permission errors after at most one successful run. I've got a bottleneck somewhere and it's looking like a murky combination of my USB and disc. So am ironing both components. I've got 64G to play with so no compromise on operating RAM.

TIA

William

[admin]

Hi William,

firstly I'm not at all sure that a ram disk is worth the hassle - you can either crank up the 'High Speed Frame Cache' option in SharpCap to 40 or 50Gb and let SharpCap do the caching of images in memory while waiting for them to be written to disk, or you can let Windows handle it. Modern versions of Windows are actually pretty good at using most of available memory for writing caching if the need arises.

As for the tracking, the best options are to use the 'center of mass' tracking and to try various movement rates to see which works the best during calibration (if you have no backlash then they will probably all work, but with any backlash higher rates may calibrate better). Also, try SharpCap 4.1 as it has improvements for feature tracking including calibrating the Dec axis first to avoid RA backlash being taken up during the Dec calibration.

If you leave the camera attached to the telescope between sessions then you should be able to avoid calibrating every session (the orientation between the camera and the RA/Dec axes will remain the same as long as the camera is not rotated).

Hope this helps,

Robin

[AstroMathmo]

Robin - many thanks - I will try out those ideas next chance I get. 4.1 does look interesting and I noted the mosaic tool too.

Ta
William