So what is the optimum image sensor size if the goal is to
maximize image quality without losing the mobility and
functionality that digital SLR cameras are capable of ?
The ideal SLR envisioned by virtually every member of
the development team was the OM-1,
a camera that revealed
its Olympus DNA with a superb combination of size, features,
and performance that made it a worldwide bestseller.
The team also wanted the new SLR to reflect
the Olympus commitment to deliver a polished,
fully integrated photographic system.
In the spring of 1999, it was with these goals in mind that
Olympus engineers began defining optical design specifications
for the ideal digital SLR system.
By the fall, they had evaluated
all possible image sensor candidates,
and it had become clear that the 4/3 (Four Thirds)
type image sensor offered an ideal balance
of high image quality and compactness for mobility.
Then, after 12 more months of research and testing,
the decision to build the new SLR camera system around
the 4/3 type image sensor was announced.

"In a way, one of the biggest challenges was that there were
no technical constraints. In short, we could do anything.
But it was necessary to consider
how technology might progress,
not just in the next three to five years,
but in the next 10 years.
And sensor size was not the only issue
- we also had to consider the various lenses
we would need to develop.
Camera bodies can be replaced,
but lenses are used for 10 or even 20 years.
So we needed to consider the system as a whole to get
the right balance overall."

Finally, in June 2003,
the world's first Four Thirds System camera
- the Olympus E-1 - was born.
The age of the E-System had begun.