There are two meanings of "last":

1. Something that comes at the end.
2. Something that came right before the current thing.

In the example above, "my last camera" means "the camera I had before this one". So it's meaning #2.

How can you tell the difference between meaning #1 and #2? It's usually easy to tell. For example, see if you can pick out which meaning is used in these examples:

My last girlfriend was a guitar player in a rock band.

I saved the last piece of the cake for you.

This is the last time I'm coming here! This place is horrible!