> CT scanner at your local hospital needs to be calibrated Of course the scanner (and any other measurement tool) need to be calibrated. Specifically, the scan

> CT scanner at your local hospital needs to be calibrated Of course the scanner (and any other measurement tool) need to be calibrated. Specifically, the scanner (and telescope) needs to be pre-calibrated based on already known samples. In case of telescope, it needs to be precalibrated based on known images of remote stars. Katie Bouman (the face of EHT imaging team), however, claims: "you [have] do not need any calibration whatsoever and you can still can get pretty good results" Check it out, she actually said that: https://youtu.be/UGL_OL3OrCE?t=1180 https://youtu.be/UGL_OL3OrCE?t=1180 I am surprised that only few people caught that flaw.