Need help in calculating digital camera's MP

On Fri, 2 Jan 2009 06:13:01 -0800 (PST), wrote:

For a 46 in high definition TV (1920x1080 Panel resolution) - 1080p
Full HD definition, the screen size of the TV is 40 in. x 23 in. ( 102
cm x 58 cm). How many MP digital camera that I need to have JPG
photos, so that I can watch clear, sharp, crisp JPG photos on the TV?
I must admit that I don't have much knowledge about the pixels in
digital cameras,etc. and how that translates into the high definition
TV. Therefore, I do need practical, layman terms answers for info or
links to specific discussion to any websites.
What about for the 52 in. TV, 56 in. TV, etc?. Is there a chart
available somewhere?. I recall a table showing how MP is connected to
photo print sizes (at the photo printing stores). But this screen size
is much larger than those listed - perhaps more for poster sizes.
Someone may ask on how close you are watching the TV screen... and I
am thinking about relatively close range, say 5 ft distance.
Thanks for the info!

Since your screen has a maximum horizontal resolution of 1920 pixels, most
3-megapixel cameras are more than enough to match or exceed that screen
resolution. You don't need more than that, nor will it increase the final
display resolution and clarity on that screen. (Provided that the camera's lens
can resolve detail down to true pixel level.**) Just because a display screen
is larger doesn't mean it will have more display pixels, and therefore more
resolution. The resolution is defined by the technology used to send and display
the video (pre-set and limited to 1920x1080), not by screen-size. Same number of
pixels, they're just made larger for a larger screen. Your resolution, (and also
color bit-depth, dynamic-range, etc.,) is never better than its weakest-link in
going from scene to recorded/displayed view. In this case the available number
of display pixels in your TV screen will be the "weakest link", unless you use a
camera with less-than 1920 pixels across its own sensor then that would become
your "weakest link".

**You should also take into account the lens quality on a camera. There is some
very poorly designed DSLR glass in most kit-lenses being sold today. You'd need
twice the sensor pixel resolution, that when downsized to a 3 or 4 megapixel
camera image will finally make each pixel convey useful information. In those
cases then the DSLR glass is the weakest link. People who choose cameras like
that are better off buying high-quality P&S cameras with diffraction-limited
quality lenses that have been optimized for the sensor resolution. Where every
pixel records and conveys useful data. Nothing wasted by matching poor glass to
an expensive sensor and losing all the resolution that you thought you paid for.
Put the typical kit-lens on a 12 megapixel DSLR and you would record more real
resolution by buying and using a 3 megapixel P&S camera instead.

HarveyW wrote:
[]
**You should also take into account the lens quality on a camera.
There is some very poorly designed DSLR glass in most kit-lenses
being sold today.

I thought that Canon had replaced their 18-55mm non-IS lens? That's the
only one which had a bad reputation. The others are excellent value for
money, and capable of excellent results. In any case, with a DSLR /you/
can choose what lens you buy, rather than being stuck with what comes with
a fixed-lens camera.

To the OP:
A DSLR or better-quality P&S of 5-6MP or better will be fine to equal
your HD TV resolution. Choose carefully, for the best image quality from
the camera. How are you going to display the images? With a computer
connection? Via the memory slot?

Cheers,
David

HarveyW wrote in
:

**You should also take into account the lens quality on a camera.
There is some very poorly designed DSLR glass in most kit-lenses being
sold today. You'd need twice the sensor pixel resolution, that when
downsized to a 3 or 4 megapixel camera image will finally make each
pixel convey useful information. In those cases then the DSLR glass is
the weakest link. People who choose cameras like that are better off
buying high-quality P&S cameras with diffraction-limited quality
lenses that have been optimized for the sensor resolution. Where every
pixel records and conveys useful data. Nothing wasted by matching poor
glass to an expensive sensor and losing all the resolution that you
thought you paid for. Put the typical kit-lens on a 12 megapixel DSLR
and you would record more real resolution by buying and using a 3
megapixel P&S camera instead.

A 3MP camera will only give better results than a 12 MP at 3MP or lesser
display if the lens on the 12MP is much worse, in an absolute, analog
sense. Pixel-level "lens" quality is totally irrelevant to this concern.

A 12MP image downsampled to 3MP will have less noise, and more pixel-level
color and luminance resolution than a native 3MP camera, with the same
quality lens.

On Sat, 03 Jan 2009 14:49:00 GMT, John Sheehy wrote in
:

HarveyW wrote in
:

**You should also take into account the lens quality on a camera.
There is some very poorly designed DSLR glass in most kit-lenses being
sold today. You'd need twice the sensor pixel resolution, that when
downsized to a 3 or 4 megapixel camera image will finally make each
pixel convey useful information. In those cases then the DSLR glass is
the weakest link. People who choose cameras like that are better off
buying high-quality P&S cameras with diffraction-limited quality
lenses that have been optimized for the sensor resolution. Where every
pixel records and conveys useful data. Nothing wasted by matching poor
glass to an expensive sensor and losing all the resolution that you
thought you paid for. Put the typical kit-lens on a 12 megapixel DSLR
and you would record more real resolution by buying and using a 3
megapixel P&S camera instead.

A 3MP camera will only give better results than a 12 MP at 3MP or lesser
display if the lens on the 12MP is much worse, in an absolute, analog
sense. Pixel-level "lens" quality is totally irrelevant to this concern.

A 12MP image downsampled to 3MP will have less noise, and more pixel-level
color and luminance resolution than a native 3MP camera, with the same
quality lens.

Any real proof of that?

--
Best regards,
John
Panasonic DMC-FZ8, DMC-FZ20, and several others

On Sat, 03 Jan 2009 08:26:09 -0800, John Navas
wrote in
:

On Sat, 03 Jan 2009 14:49:00 GMT, John Sheehy wrote in
:

A 12MP image downsampled to 3MP will have less noise, and more pixel-level
color and luminance resolution than a native 3MP camera, with the same
quality lens.

Any real proof of that?

The only real reason higher a 12 MP sensor of the same size as a 3 MP
sensor may seem to have less noise when downsampled to the same size
would be better noise reduction -- there hasn't been anywhere near that
much progress in sensors, which have been near the quantum efficiency
limit for some time.

--
Best regards,
John
Panasonic DMC-FZ8, DMC-FZ20, and several others

John Navas wrote in
:


Any real proof of that?

The only real reason higher a 12 MP sensor of the same size as a 3 MP
sensor may seem to have less noise when downsampled to the same size
would be better noise reduction -- there hasn't been anywhere near
that much progress in sensors, which have been near the quantum
efficiency limit for some time.

Back when cameras had 3 MP, quantum efficiencies were lower. Now, they're
leveling off, but read noise is not increasing as fast as linear pixel
density (sensor PPI). In fact, it is generally decreasing, so image-level
read noise is generally going down.

On Mon, 05 Jan 2009 01:09:44 GMT, John Sheehy wrote in
:

John Navas wrote in
:

Any real proof of that?

The only real reason higher a 12 MP sensor of the same size as a 3 MP
sensor may seem to have less noise when downsampled to the same size
would be better noise reduction -- there hasn't been anywhere near
that much progress in sensors, which have been near the quantum
efficiency limit for some time.

Back when cameras had 3 MP, quantum efficiencies were lower. Now, they're
leveling off, but read noise is not increasing as fast as linear pixel
density (sensor PPI). In fact, it is generally decreasing, so image-level
read noise is generally going down.

The improvement in quantum efficiency has been small, and the difference
is sensor noise has likewise been small. What's been big is the
improvement in noise reduction.

--
Best regards,
John
Panasonic DMC-FZ8, DMC-FZ20, and several others

On Tue, 06 Jan 2009 04:20:05 GMT, John Sheehy wrote:

John Navas wrote in
:

The improvement in quantum efficiency has been small, and the
difference is sensor noise has likewise been small. What's been big
is the improvement in noise reduction.

NR is madness, at the level it is practiced in many cameras, especially P&S
cameras. Companies do NR for the idiots who judge cameras at 100% pixel
view, and wouldn't know an honest-looking image if it bit them in the face.
I only concern myself with RAW noise.

Especially since you can almost always to NR better on your PC than in
the camera.

However, I disagree that 100% pixel view is unimportant. It all
depends on how big you want to print your pictures. I sometimes make
prints out of my 10MP DSLR at up to 20x30". Even if I don't have
wasted pixels due to cropping (which I frequently do even if just to
get to the correct aspect ratio) that works out to under 130
pixels/inch. And they're often viewed at only like a foot away. In
this case, pixel level noise, chromatic aberration, etc., are all very
important. There's no way I'd even bother to make a 20x30" print from
a 10MP P&S because it'll look like crap. But from a 10MP DSLR they
can look great.

Steve

"TheRealSteve" wrote in message
...

On Tue, 06 Jan 2009 04:20:05 GMT, John Sheehy wrote:

John Navas wrote in
m:

The improvement in quantum efficiency has been small, and the
difference is sensor noise has likewise been small. What's been big
is the improvement in noise reduction.

NR is madness, at the level it is practiced in many cameras, especially
P&S
cameras. Companies do NR for the idiots who judge cameras at 100% pixel
view, and wouldn't know an honest-looking image if it bit them in the
face.
I only concern myself with RAW noise.

Especially since you can almost always to NR better on your PC than in
the camera.

However, I disagree that 100% pixel view is unimportant. It all
depends on how big you want to print your pictures. I sometimes make
prints out of my 10MP DSLR at up to 20x30". Even if I don't have
wasted pixels due to cropping (which I frequently do even if just to
get to the correct aspect ratio) that works out to under 130
pixels/inch. And they're often viewed at only like a foot away. In
this case, pixel level noise, chromatic aberration, etc., are all very
important. There's no way I'd even bother to make a 20x30" print from
a 10MP P&S because it'll look like crap. But from a 10MP DSLR they
can look great.

Steve

Yes I reckon with a decent lens you can still get good detail at 60" x 40".
I wish I could afford prints that size but I know the detail is good because
I have done small test prints of a portion of this sized photo.

Roger

On Tue, 6 Jan 2009 17:15:04 -0000, "Roger Blackwell"
wrote in
:

However, I disagree that 100% pixel view is unimportant. It all
depends on how big you want to print your pictures. I sometimes make
prints out of my 10MP DSLR at up to 20x30". Even if I don't have
wasted pixels due to cropping (which I frequently do even if just to
get to the correct aspect ratio) that works out to under 130
pixels/inch. And they're often viewed at only like a foot away. In
this case, pixel level noise, chromatic aberration, etc., are all very
important. There's no way I'd even bother to make a 20x30" print from
a 10MP P&S because it'll look like crap. But from a 10MP DSLR they
can look great.

Yes I reckon with a decent lens you can still get good detail at 60" x 40".

Not in 35 mm.

--
Best regards,
John
Panasonic DMC-FZ8, DMC-FZ20, and several others