Now that spring appears to have arrived, I have got the Sol'Ex out again and have connected it to the SVBony 80mm F7 refractor that is my workhorse. As I need to try and capture full disk images, I am also using a 0.8 Focal Reducer specifically designed for imaging with this telescope.
There is a ND8 Urth professional filter fitted in a homemade 3D printed housing to absorb most of the sunlight (importantly the heat). This appears to be working OK or rather, I haven't shattered the slit again. Camera is a ZWO ASI178MM Mono.
First tests with the new setup were carried out on last Sunday evening (20250420), not an ideal time of day as there was distinct high level cloud and the sun was quite low in the sky..
The change in optics from the smaller 60mm f4 refractor that I had previously used resulted in a much more detailed image. What is initially obvious is the cloud on the left of the image but all in, I was quite pleased with this.
The JSolex application that I use to process the images produces a few variations, including doppler shifted images. This allows you to calculate the rotation speed of the Sun for example. There is also a variant of an eclipsed Doppler image. The large prominence at the top right (North West) showed a very interesting doppler pattern.
This is a 100% sized crop. Careful examination shows the Blue (plasma moving away from you) and Orange (plasma towards away) to be twisted in a whirlwind formation. I assume that this is a tornado class prominence but it doesn't fit with the standard descriptions. More investigation required!
I used the Sol'Ex for the next 3 days. One thing that I have noticed is that the new optical setup accentuates any errors in the Sol'Ex optical train. The following day, I noticed that the images were being cropped when imaging the CaK spectral line. The crop was still within the boundary of the camera sensor so was being lost elsewhere. Carefully shimming the grating improved matters but now caused the same problem at Ha but on the other side of the camera sensor. Nothing of significance for the 21st April as I was trying to resolve this problem.
That particular problem is still work in progress.
On the 22 April, I tried again at Ha.
A very cut down image but the long looping prominence to the North East looks very interesting.
The doppler image:
The sharp edges are a processing artefact but you can see that the bulk of this prominence is moving towards us (with the rotation of the sun) with the top edge of the prominence moving away.
Finally, on the same day, this is the West North West hemisphere in Ha.
I suspect that the prominence is still the same prominence that I observed 2 days earlier. The image does give a good indication of the resolution and hence detail that can be seen using a spectroheliograph.
The tornado seems to be going strongly, in fact, I think the spiral is more obvious in the image.