Why not make the sensor larger?

Espagnol wrote:
In article , John
McWilliams wrote:

one of my favourites is 'near miss.' not only was it a near miss, but
it was a complete miss.
Could you 'splain on that a bit? It doesn't seem odd to me to
categorize misses as near or far or close or wide.....

a near miss is used to refer to a narrowly averted collision.

Sure, if you're talking FAA, or other undesirable air or land craft
meetings.

a 'near
hit' is a more accurate description for a collision that almost occured
but didn't, not a near miss. it did miss.


In target shooting a near miss is way better than a far miss. But mebbe
I miss your point.

--
john mcwilliams

I finally found some time to go through the Janesick article. It
contains nothing that contradicts what I posted. You originally wrote:

And back to your original idea of multiple short images:
you can't read out these large (8+ megapixel) chips
fast enough to do what you want and follow action.
There was a thread about this earlier and I posted links
to web pages that shows the speed of moving electrons
from the potential wells to the amplifiers is actually
quite slow (it is not the speed of light that many
people seem to think).

But for instance in CMOS sensors charges do not have to travel a couple
of cm along a row of pixel in a CCD manner - they can be addressed
individually. The Janesick article does not state that readout times for
individual CMOS pixels are huge (in fact no figures are provided).

In any case, the proof that my suggestion actually works is the fact
that a such a multiple read sensor actually exists:

http://www.toshiba.com/taec/news/pre...ssp_07_466.jsp

Also have a look at the PDF white paper at
http://www.techonline.com/learning/techpaper/197700819



In article , says...
Alfred Molon wrote:
In article , says...

In that case there are two options:
1. You only make one final readout (R) and you discharge each cell when
it reaches a predefined fill level (F), and count the number of
discharges (N). The pixel value is then N x F + R.
To figure out if the cell is full, you must read it out.
Multiple readouts contribute read noise to the final signal.

You can place in each pixel circuitry which compares the voltage in the
pixel with a predefined value. When this predefined value is reached,
the circuitry discharges the cell.

I think you should read up on how CMOS sensors actually work.
Yes, you need to move the charge out of the pixel in order to
measure it. See:

http://huhepl.harvard.edu/~LSST/gene...paper_2003.pdf

Note some key points i n the article:

"The third function, charge transfer, is critical to
CCD operation. CMOS pixels are directly addressable
and are not as sensitive to charge transfer problems.
However, charge transfer CMOS pixels must deal with a
serious problem called image lag. ...."


2. You don't transfer the charge to the output, only a voltage. The
charge is converted to a voltage in each pixel and this is read out
through a standard multiplex line. I think CMOS chips work like this if
I'm not mistaken.
Where do you think a voltage comes from? (e.g. electrons
stored in a capacitor). To clear the pixel, you must
get rid of the charge, and that means moving electrons,
thus moving the electrons off chip.

Should you continually move electrons out of the chip, after a while
there would be no more electrons in the silicon! The electrons which are
created in a pixel when light hits it are taken from the pixel itself,
so discharging the pixel simply means eliminating the imbalance in the
pixel.

What do you think the power supply does? It supplies the
voltages and current to move the electrons around as needed.

In any case, the electrons don't travel a couple of cm (in a CMOS
sensor), therefore the time required by the readout process is very
short. You were claiming initially that electrons must travel a large
distance (up to 1-2 cm) to be read out and that that takes time.

Again, citing the above paper:

"The last imaging operation involves measuring the signal charge
contained in each pixel. Readout for CMOS and CCD
imagers is the same, and in theory, can achieve similar noise
floors (i.e., a few electrons). Both imagers use a sense node
capacitor to convert charge to voltage and a source follower
MOSFET amplifier to buffer this output voltage."


--

Alfred Molon
------------------------------
Olympus 50X0, 7070, 8080, E3X0, E4X0 and E5X0 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

In article ,
says...

I don't "refuse to accept this" - however it does seem that YOU refuse
to accept that the geometry of the microlens and the active area
underneath it can be, and indeed have been, optimised.

How?
--

Alfred Molon
------------------------------
Olympus 50X0, 7070, 8080, E3X0, E4X0 and E5X0 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

In article , says...

Yes, an improvement, but not complete elimination of the problem. The
penalty being a larger lens mount diameter (relative to the sensor size),
and hence compromising the ability to produce a really compact system.

The Olympus E400 is currently the most compact DSLR on the market.
--

Alfred Molon
------------------------------
Olympus 50X0, 7070, 8080, E3X0, E4X0 and E5X0 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

In article ,
says...

And what happens in each pixel while the discharging is done? I must
assume that this takes place in the different pixels at different
times, and thus some will discharge more often than others, and thus
miss more light than others.
If you include some sort of algorithm to try to figure out what must
be the right exposure for each pixel according to what the programmer
thinks is proper exposure, despite what the photographer wants, I can
see this sort of working.
But the current system seems to work pretty well.

The assumption here is that this discharge time is so short not to
matter, or you can, as you suggested, use some algorithm to estimate the
light lost during the discharge phase (works if the scene is static or
semi-static).
--

Alfred Molon
------------------------------
Olympus 50X0, 7070, 8080, E3X0, E4X0 and E5X0 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

"Bill Funk" wrote in message
...
On Mon, 18 Jun 2007 14:23:33 -0400, "Neil Harrington"
wrote:

Who really cares what you think, as it doesn't relate to reality.
Everyone except you understand the term "crop factor". It's you who
has the problem, not the rest of us.
Do you really think everyone else has it wrong, and your Johnny is the
only one in step?

But it isn't "everyone else." There are billions of people in the world
and
hundreds of millions of them own cameras, increasingly digital cameras.
How
many of all those people ever exchange views on this or any related
newsgroup? Very, very, very few. Among that exceedingly small fraction of
one percent, the nonsense term "crop factor" has achieved a certain
currency.

Does Nikon ever use the silly term? No. Don't you think Nikon's literature
and online material would include the term if it were valid?

Pop Photo and other publications use the term "lens factor." That's what I
call it too. Compare the readership of Pop Photo with that of this
newsgroup
and then tell me all about "everyone else."

We went through this before, remember?

It does all have a familiar ring, all right.


I demonstrated that, despite your claim, the term is used by camera
makers.

Was that you who directed me to Canon's use of the term? Shame on Canon.
Canon (presumably previously) used the proper term, "lens focal length
conversion factor." Some low-level person at Canon must have gotten
misinformation from NGs since then. These things happen.

But "camera makers" is plural. Canon is just one.


Your insistance on "proper usage" is strange, since you still continue
to not understand that usage changes, and what is understood is
proper, whatever the dictionary (or you) say the individual words in
any given term mean when used alone.
That Nikin doesn't use the term is not a valid point, since Nikon also
doesn't use "IS" to describe their vibration reduction technology in
their lens descriptions; they use "VR" instead. Do you also claim that
Canon's use of "IS" is wrong because Nikon doesn't use it?

No, "image stabilization" is actually the best term, I think. But for some
reason every camera maker seems to feel he can't use anyone else's term for
it. Nikon uses "VR" as you say. Minolta used "Anti-Shake" (now that it's
Sony, it's "Super Steady Shot"). Panasonic says "Mega O.I.S." And so on.


Oh, look: there's a windmill! Off with you, now.

I don't do windmills.

Neil

"Philip Homburg" wrote in message
.phicoh.net...
In article ,
Neil Harrington wrote:

"Philip Homburg" wrote in message
. hq.phicoh.net...
In article ,
Neil Harrington wrote:
What does anyone *do* with that 1.5, other than multiply the actual
f.l. with it in order to get the 35mm-equivalent f.l.?

Multiply it with the aperture to get the equivalent aperture?

I hope not! There is no different "equivalent aperture."

There is for DoF and total number of photons (assuming equal total number
of pixels).

Differences in those things, yes. But the f/ number still doesn't change.

Neil

In article ,
Neil Harrington wrote:

"Philip Homburg" wrote in message
q.phicoh.net...
In article ,
Neil Harrington wrote:

"Philip Homburg" wrote in message
.hq.phicoh.net...
In article ,
Neil Harrington wrote:
What does anyone *do* with that 1.5, other than multiply the actual
f.l. with it in order to get the 35mm-equivalent f.l.?

Multiply it with the aperture to get the equivalent aperture?

I hope not! There is no different "equivalent aperture."

There is for DoF and total number of photons (assuming equal total number
of pixels).

Differences in those things, yes. But the f/ number still doesn't change.

The focal length doesn't change either.

ploink.


--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
-- Douglas Adams in Dirk Gently's Holistic Detective Agency

"Neil Harrington" wrote:
"Philip Homburg" wrote:

There is for DoF and total number of photons (assuming equal total number
of pixels).

Differences in those things, yes. But the f/ number still doesn't change.

In the film days, everyone used the same "sensor" (well, set of sensors)
regardless of format size.

That meant that the f/number abstraction made sense, since it told you the
flux per unit area of film, and you knew how film responded to flux per unit
area.

But it makes less sense for dcams. The FZ20 folks think they have a 450mm
f/2.8 lens, when the flux per pixel is a fraction of what the 30D sees from
a 300mm f/5.6 zoom.

David J. Littleboy
Tokyo, Japan

"Neil Harrington" wrote in
:

Why do so many young guys
put their baseball caps on backwards? (I sometimes see men in their
40s and 50s doing the same thing, which looks even more stupid, if
possible, than when kids do it.)

If you see me doing it, it is because I brought the wrong hat with me, and
I can't use my DSLR and flash with the visor in the front.

If you see my pants hanging down near my knees, it's because I forgot my
belt. If I have one pant leg inside my boots, and one outside, and both
boots untied, it's because I'm sloppy.

--


John P Sheehy