Yep it’s a photography, with some post processing to make it looks like a painting.
The niche is probably 15th century stuff, but its original purpose is difficult to determine. The board inside is actually not an ex-voto. It bears the name of Paul Georges Marie Dupont des Loges, bishop of Metz between 1828 and 1886, as well as MP of Moselle in the Reichstag between 1874 and 1877. Thus, it is probably rather a memorial of the visit of that bishop in the church of Fénétrange.
Tools and exifs:
- Canon EOS 450D + Canon 18-55 IS
- 1/5 s.
- ISO 1600