You know how a tiny, toy magnifying glass can burn little pieces of paper? Well, the camera lens is a not a small, toy, magnifying glass by no means, it is a powerful well-polished tool of optics and using it in the wrong way – say to photograph the sun during an eclipse – can be devastating to the camera sensor. The team at Everything Photography did a little experiment and showed what an unfiltered six seconds exposure would do to your sensor. TL;DR – it fries te sensor. The team took a (probably dead) Canon T2i connected to a (probably) 400mm unfiltered lens and pointed it at the sun. The first noticeable thing is that you definitely don’t want to look at the viewfinder while the camera is pointed at the sun. It narrows the sun image into a very small space which is likely to burn your retina. The next experiment was a six seconds exposure which nuked the mirror mechanism and “dented” the sensor. but the most interesting thing of all was a very long “exposure” done with the mirror held back with a paper clip. It looks like a plasma beam out of Star Trek simply frying the sensor.
Sadly, the sensor did not have any photon torpedos to fight back, and it got annihilated.
The moral of the story: know what you are doing when shooting the eclipse. [How to MELT your camera shooting the eclipse via fstoppers]