At 1/1000 of a second, the shutter of the camera does not manage to synchronize properly so it seems and so a pretty sharp picture has these strange variations in brightness. My assumption is that it is the shutter. The lens was a 300mm Sonnar (built since 1936-today), the camera a PraktinaFX (1954), the film was Kodak Supra 400. Settings f4 / 1/1000s.