context: The exact date for the start of color filming by Prokudin-Gorsky in the Russian Empire has not yet been established. The most probable fact is that the first series of color photographs was taken during a trip to the Principality of Finland in September-October 1903.
question: When did Sergei Mikhailovich Prokudin-Gorsky take the first color photograph?
answers.text: September-October 1903