Mike Jacoubowsky wrote:

Sorry, nothing can be done about small sensors. It seems to be a
"cartel" decision not to offer decent size sensors in P&S cameras.

Not exactly. Larger sensors dictate larger lenses. And larger lenses
make for a... bigger camera. Darn, hate those simple laws of physics.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


That's not really correct...

There were also a lot of small pocketable cameras in the 35mm-film age,
when
there were no digital sensors.... And they were able of having things
like a 3x zoom and things like that. The lenses weren't really/much
bigger than of current pocketable digicams.

examples: Fujifilm DL-270 ZOOM, Pentax IQZoom 115, .. just look for
compact
cameras at ebay

--Dennis

Afraid the laws of physics still apply. I took a quick look at the Pentax
you listed; at wide-angle, the max aperture is F4. The Fuji is even worse,
at F5. That's how they got the lens size down, no magic involved. If
you've got a large imaging area (either film or digital sensor), it's
going to take a correspondingly large piece of glass for the same amount
of light to hit the sensor.

Small cameras, whether film or digital, simply cannot disobey the basic
laws of physics. You can make the lens smaller (and thus camera size) by
either using a smaller sensor or giving up an F stop or two.

Perhaps we could evolve a digital sensor so incredibly sensitive that it
could be very small and noise-free, such that a lens with a max aperture
of F8 is all that's needed. That could really get size down! But then I'm
told there are problems with such a small lens, due to the refraction of
light at extreme angles (if I've got this right). Did pinhole cameras have
such
issues? :)

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


Yeah, of course the lens will let through less light, but that doesn't mean
it's not possible.

With a bigger sensor you can then push up the ISO, and it will be less
noisy. Of course the lens will let less light through. So in the end you
might have the same, if there wasn't diffraction.

And I also think the factor of the lens letting light through depending on
the image circle is not directly proportional to a sensor being more or
less sensitive to light and being more/less noisy depending on the image
circle it can capture.

I think that it behaves more exponential at sensor size, but linear in lens
size? I'm not sure at all, but to my observation it looks like that (at
least as a rule of thumb).

So, I think, a bigger and more sensitive sensor and slower (letting less
light through) lens will be a better combination than a fast lens and small
sensor. (also because of the diffraction, and yes pinholes can suffer from
diffraction, but if you have a larger format camera it will be less)

--Dennis