Yes. There are many pictures of Flameng in Russia taken during the execution of this painting, kept at the Ecole des Beaux-Arts in Paris. Flameng is sitting next to his wife (Henriette Flameng, daughter of a prominent French politician).
Like the imperial family, Flameng was passionate about photography.
Note that in 1901 (or 1896, I'm not sure), when Nicolas II comes to France, he notices Flameng and comes to shake his hand in person. It says of Flameng's affinity with the imperial court of Russia.