Looks a lot like Sinbad though it is a lot taller than mine the color and leaf shape are about the same.
A very pretty plant whatever variety it may be. How much sun is it getting? Do you keep it outdoors or is that just for the photo session?

Beth (?)

I'm in Central Florida so all the begonias stay out year round. In summer it gets late afternoon sun, maybe even that is too much as a couple of leaves have browned. I think you have successfully ID'd the plant. Internet pictures and descriptions of 'Sinbad' sound exactly like my plant. Many thanks!