I'm guessing, but it's probably because, in the film cameras, anyway, 
one looked and focused
through the single lens via a 45 degree mirror (reflector) which flipped 
out of the way when the
shutter was released. A prismatic reflector reflected the light through 
the view finder (and corrected
the image reversal caused by the first mirror). I don't suppose digital 
SLR's need these mirrors;
perhaps they are called SLR's because the look like SLR's.

David

Darren New wrote:
> Florian Pesth wrote:
>> IIRC Darren asked, why a DSLR is called *single* lens reflex camera. 
> 
> Actually, I asked why it was called a single lens *reflex* camera. But 
> that's cool. :-)
>

Post a reply to this message