John Francis wrote:
On Fri, Sep 30, 2005 at 09:03:57AM +0100, Cotty wrote:
Yes but I don't understand - why continue to try and get the best out of
a smaller sensor? Surely the aspiration of all SLR camera makers who have
ventured into digital, is to produce a DSLR that captures the full 35mm
frame? Anything else is surely too complicated for most people to
understand WRT smaller chips mean that lenses don't work quite the same
way as before etc etc. Or is the 1.5 crop here to stay forever, as a sort
of 'new format' along with a smattering of 'D' lenses?
The 1.5 crop is here to stay. Most of the people now buying DSLRs have
never owned a 35mm film camera in their lives, so they have no "before"
experience to confuse them.
But they've still heard about the crop, haven't they? 1:1 sounds better
than 1:1.5 even if you have no past experience with 1:1...
But, basically, it's simple economics. [ ... ] That extra
$1000-$1500 just isn't worth it to the majority of prospective purchasers.
What people will pay extra for (but I'm not sure how much), is a higher
number of MP - even if they don't really need it. And (see below) maybe
after a certain point is reached, the only real way if increasing it is
to make the actual sensor larger.
And I believe Canon can - if they want (maybe they have started
already?) - make "Full Frame" such an important buzz-word that people
will want one, and be willing to pay quite a bit of extra for it, even
if they really have no idea what it implies.
[ ... ] And while larger pixels
do allow for better signal-to-noise ratios, that's an area where I expect
technology to continue to improve over the short-to-medium term.
As I've mentioned before, I've been wondering about how much more it can
be improved. Well, maybe the *ratio* can in theory be infinite because
you can imagine having no noise at all, but how much better can they
make the actual signal? And how much smaller can one sensor element be?
I mean, there's only a finite amount of light that can reach the
element, and the "light amount" range and therefore also the sensor
output range, is actually made up of a number of discrete values.
(That's quantum mechanics. Actually, I think the sensor would have a
quantum behaviour even if the light were continuous.) This means that
even if can register *all* the light (i.e. count all the photons, so as
to speak) there is a clear limitation to what kind of value range you
can get. Also, the amount of light available obviously depends on the
element size, and you can only reduce the size so much and still be able
to collect enough light to make a usable signal - even with an ideal sensor.
Another advantage of a larger area, is that you are less restricted by
the resolution limitations of the lens because you use more of the
glass, so as to speak.
- Toralf
