In article , Bill Funk
writes
On Mon, 2 Jul 2007 22:57:23 +0100, Prometheus
wrote:

In article , Allen
writes
SJ wrote:
Kind of a Newbie question on sensor size.
What is the difference between, 1/2.5 " or 1/1.6 " or 1/1.8 " on
non-slr's or 4/3" or 23.7 x 15.6 mm on a Nikon. Do more or bigger
sensors necessarily mean better pictures? and If so, why? thanks
Scott
The naming schemes used to describe sensor size is ridiculous. Why
can't they say '0.4"' instead of '1/1.6"', for instance, and actually
give the other rectilinear dimension also. Actual size (in mm would
make much more sense. I assume that somewhere in the deep dark reaches
of digital camera history some people thought that these strange and
illogical sizes would have some marketing edge; behind just about any
illogical description in any commercial lies a marketing decision. I
will now step of my soapbox (for now).
Allen

It was not ridiculous in it origin. The size originally refereed to the
diameter of a TV tube, the diagonal of the sensitive element being about
2/3 of the tube. When CCD sensors where introduced the equivalent tube
diameter for a given diagonal was used because users could relate it to
the lens required and purchase a CCD camera which would use the lenses
they already had. There is now probably far more different sizes of CCD
than there ever were tubes.

The first consumer digital cameras weren't DSLRs, so fitting the
correct size lens wasn't an option; the lens was fixed.
IMO, the sensor sizes were given the way they are in order to not
scare consumers away with the small sizes of sensors being used. Since
most consumers were using film sizes much larger than the sensors in
those first cameras, the marketing dep'ts wanted the cameras judged on
the merits of the images provided, not the sizes of the sensors.
Giving the sizes in an obscure measurement system that most consumers
would not bother to understand served that purpose.

All very true, but the first CCDs were on TV cameras, hence the
importance of describing the CCD by the size users were familiar with,
i.e. 1, 2/3, 1/2. What is nonsensical is describing sensor sizes never
used in TV cameras by improper fractions, i.e. 1/1.8 and 1/2.7 have
sensor diagonals of 9 and 6.6 mm.

--
Ian G8ILZ
There are always two people in every pictu the photographer and the viewer.
~Ansel Adams