pedro wrote: ↑Mon Nov 13, 2023 5:45 pm
I have to say that I'm still struggling to get decent results with my Sol'Ex.
Hi Pedro, I noticed in a different post you said you were struggling with the Solex. A minor improvement can be achieved with a camera with the slightly smaller pixels than the 174MM. It turns out the best camera sensor to use with the Solex is the IMX533 (which I think you have). The 178MM will actually oversample, which is why you see a lot of 2x2 binning with the 178MM and the Solex.
The most difficult thing to get right is the collimator focus. I think you are probably close but not quite perfect. I would actually take out the collimator and slit module and collimate it the old fashioned way. That means getting a camera and lens (or finderscope) that is focused at infinity. Point this towards the collimator lens and make sure the illuminated slit is sharply focused by adjusting the slit to collimator lens distance. I prefer to do this using a red filter so it is collimated for H-alpha.
Once it is all put together, you need to focus the camera so that the spectral lines are sharp. Then finally focus the telescope (the easiest is to make sure the limbs are sharp). I see that you have a fairly large piece of dust or dirt on the top part of your slit and a smaller piece right in the middle. Assuming that these are on the lithographically patterned slit side (which is almost impossible to clean in the Solex design), they should appear as sharp vertical lines, about as sharp as the horizontal spectral lines. In the transversalium correction graph, they will appear as sharp vertical peaks.
It's possible that the larger piece of dirt is on the glass side of the slit that faces the telescope -- that side can be cleaned. I actually wouldn't attempt to clean the lithographic slit side that is hidden inside the slit holder except by blowing with something like a Giottos Rocket air blower.
