About my photo: it was taken around 20:50 EET (probably 17:50 UTC) from somewhere near Tallinn, Estonia, with an 8 megapixel mirror camera. I used ISO 100 and exposure 1/4000 seconds. The upload has been scaled down to save server resources. The lens was an old and big reflector lens (probably 1:10, focal length around 1 meter). Since it was the very utmost sunset (sun at elevation below 5 degrees), a lot of atmosphere was in the way (probably about 1000 km of atmosphere). I checked my own safety and that of the camera, had to wait a little, and finally was able to take the photo without a solar filter (never do that without consulting your camera doctor) and I was able to view the viewfinder with mere very good sunglasses (never do without consulting your medical doctor) and I have no eye damage. Yay. :)
Coincidentally, the same as I used for my eclipse picture.
They’re not rare in Eastern and Central Europe, and cost about 200…300 euros (more if the kit is complete or the lens has been well preserved, because some of them are 45 years old now).
Of course they are inconvenient (massive weight, no control over aperture), but this quickly stops mattering when a well-known camera brand charges several thousand for similar optics. :)
I’ve used mine to photograph a plane from 50 km distance. Of course I had to know in advance where the plane was, and weather had to be perfect, but it was doable. I could not catch a plane at 100 km, but I was able to snap a barely recognizable ISS from over 1200 km (I was in Estonia, ISS was passing from Poland to Ukraine). This I will try to re-attempt later, because the blob required lots of post-processing to start resembling a space station. :)