Troubleshooting Solar photography
Solar photography brings along its own set of problems. On this page I will describe the ones I have encountered, their cause and fix.
On a solar telescope you most probably have an aiming device. It would actually be silly if you didn't. There a a few types and mine is a Televue Sol-Searcher. A quite simple but yet very effective device. Two discs of which the front one has a small hole so light of the sun hits the back disc on a designated spot. This happens exactly along a line parallel to the optical axes of the telescope. So... lightspot on the right place and you'll have the sun in your eyepiece or camera. But what I found on a certain moment was no sun while it was perfectly centered on the back disc. Once I finally found the sun and had it perfectly in my eyepiece the spot on the back disc was what was on the picture here on the right. This puzzled me and I couldn't get a grip on the problem. This was supposed to be impossible. Until a few days later...
I set up the scope again and again the same problem. But once I found the sun and started focussing I noticed an instability, my scope was wiggling😱. The mount had a secure tight grip so that wasn't wrong but... The two screws that bolt the Vixen dovetail rail to the scope were loose🤯. My €6.000 scope was technically dangling on the rail. Somehow the screws (that by the way have an impossible Allen key size of 3/16") had loosened themselves while frequently (dis)mounting. So...If you encounter this, check your dovetail mounting rail!
Forming the image.
There is a clear hard shadow and you feel the sun burning but... no sun in the eyepiece or in the camera...
Good chance that the seeing is bad. Even a thin veil of cloudiness high up in the sky (Cs or Cirrostratus cloud) can block the sun totally from the telescope. The filters are so dense that the slightest obstruction will blackout the image. Viewing this problem in a wider perspective: the sun looks complete and well lit in your eyepiece but on camera there is a lineair fading in clarity: a tiny bit of Cirrostratus or even remnants of an airplanes contrail causes this.
Even when the sun starts hiding behind a leaf on nearby foliage you will have loss of light. This is clearly an extremely sensitive device!
In the eyepiece and/or camera image is a glare in the blackness of space surrounding the image of the sun.
Are you viewing from under a painted roof-like construction? From a balcony with a painted overhead construction? The reflection of the sunlight from a more or less reflective coating is picked up by the scope.