Actually the vampire would show up on a digital camera. The actual myth is that SILVER does not reflect vampires. The fluids used to develop film contain silver and mirrors used to be made of silver. So in turn unless a digital camera used silver wiring and LSD (Liquid Silver Display) then a vampire would show up in the preview, but if it were printed using silver based ink then he would not be in the printout.

Oh yeah same as fondue it is all hypothetical because real vampires don't exist, just crazy people who drink blood.