Einstein’ theory was first proven correct when Einstein himself used it to calculate Mercury’s precession of perihelion. It had never been done successfully until then. Einstein said that it gave him heart palpitations.
Eddington had a hell of a time with getting his results.
It reminds me of a camera-carrying rocket that was sent above the atmosphere to do some star shooting back in the day. The film was ejected and captured as planned.
When the film was developed, it was revealed the camera aperture had been set for ASA 400 film, not the ASA 100 that was loaded. The underexposed B&W film was unusable and was given to an Army tech to do with as she chose.
She irradiated the film, making the metallic silver molecules radioactive. Then she contact-printed the negative using the radiation as the light source. Pulled out the job.