megapixels and sensor size

Since it looks like Canon is coming out with a full 35mm frame sensor,
and it's about 6mp, would that be the equivalent to the current sensor
size but with 3mp?

I would think for the same density of megapixels in the larger frame,
the number of MPs would go up proportionately.

Or is this not right?

I would think for the same density of megapixels in the larger frame, the
number of MPs would go up proportionately.

Maybe each of the pixels are bigger?

Toa

"Jon Nadelberg" wrote in message
...
Since it looks like Canon is coming out with a full 35mm frame sensor, and
it's about 6mp,

The 5D has 12.8MPs

would that be the equivalent to the current sensor size but with 3mp?

The 5D sensor surface area is 2.535 x the 20D sensor so presumably
12.8/2.535 = 5MPs

I would think for the same density of megapixels in the larger frame, the
number of MPs would go up proportionately.

Or is this not right?

Yes (if I understand the question)

"John A. Stovall" wrote in message
...
On Sun, 28 Aug 2005 19:26:09 +0100, "dylan" wrote:


"Jon Nadelberg" wrote in message
...
Since it looks like Canon is coming out with a full 35mm frame sensor,
and
it's about 6mp,

The 5D has 12.8MPs

would that be the equivalent to the current sensor size but with 3mp?

The 5D sensor surface area is 2.535 x the 20D sensor so presumably
12.8/2.535 = 5MPs

No, the 5D pixel size is 8.5x8.5 µm while the 20D pixel size is
6.4x6.4 µm.

No ?
Is that what he meant, pixel size not sensor size ?, not how I read it but
you maybe right.

dylan wrote:
"Jon Nadelberg" wrote in message
...

Since it looks like Canon is coming out with a full 35mm frame sensor, and
it's about 6mp,


The 5D has 12.8MPs


Oh, ok. So, 12.8 MPs.

So the density of pixels is about the same, just a bigger area.

I guess I'm just trying to see where MP counts come in when you have a
different sensor size. Since the 5D has such a larger sensor, then the
12.8 MP would not be equivalent in resolution to a 12.8 MP camera with a
smaller sensor, such as a D2X (not that I'm about to buy that....).

Also, if the pixel size is a bit larger, how does that affect
resolution? I would think a larger pixel size would reduce resolution,
but probably not where it is really noticeable.

John A. Stovall wrote:
On Sun, 28 Aug 2005 11:10:04 -0700, Jon Nadelberg
wrote:


Since it looks like Canon is coming out with a full 35mm frame sensor,
and it's about 6mp, would that be the equivalent to the current sensor
size but with 3mp?

I would think for the same density of megapixels in the larger frame,
the number of MPs would go up proportionately.

Or is this not right?


It's 12 megapixels and here is what you want to know...

http://www.dpreview.com/articles/canoneos5d/

A comparison of pixel density and size to sensor size...

OK, read it. So they did make the pixels large to compensate for the
larger sensor size. I assume that because the canon EOS 1DS has a
larger pixel size than the Nikon D2X, but has a bigger overall MP count,
that the Canon has a somewhat larger sensor than the Nikon.

So, if you increase the pixel count for the 5D, how much resolution do
you lose? It seems to me that while it has a full frame sensor, it is
simply not going to have close to the same sort of resolution that you
could get with smaller sensor 12.8 mp cameras.

"Jon Nadelberg" wrote in message
...
Since it looks like Canon is coming out with a full 35mm frame sensor, and
it's about 6mp, would that be the equivalent to the current sensor size
but with 3mp?

I would think for the same density of megapixels in the larger frame, the
number of MPs would go up proportionately.

Or is this not right?

See the pixel comparison, he
http://www.dpreview.com/articles/canoneos5d/

Near the bottom of the page.

BTW, the 5D is 12.8 megapixel, not 6. Six was passed a couple of
generations ago...
--
Skip Middleton
http://www.shadowcatcherimagery.com

Oh, ok. So, 12.8 MPs.

So the density of pixels is about the same, just a bigger area.

I guess I'm just trying to see where MP counts come in when you have a
different sensor size. Since the 5D has such a larger sensor, then the
12.8 MP would not be equivalent in resolution to a 12.8 MP camera with a
smaller sensor, such as a D2X (not that I'm about to buy that....).

The D2X will have higher resolution (its covers a smaller area of the image)
BUT theoretically will have a worse noise figure due to smaller pixels.
read the bottom of this page http://www.dpreview.com/articles/canoneos5d/

Also, if the pixel size is a bit larger, how does that affect resolution?

It's obviously lower but noise is better.

I would think a larger pixel size would reduce resolution,
but probably not where it is really noticeable.

Resolution is noticable, all other things equal, until you reach the limit
of the eye.

Cheers

OK, read it. So they did make the pixels large to compensate for the
larger sensor size. I assume that because the canon EOS 1DS has a larger
pixel size than the Nikon D2X, but has a bigger overall MP count, that the
Canon has a somewhat larger sensor than the Nikon.

So, if you increase the pixel count for the 5D, how much resolution do you
lose?

None you improve resolution

It seems to me that while it has a full frame sensor, it is simply not
going to have close to the same sort of resolution that you could get with
smaller sensor 12.8 mp cameras.

Correct, but you will find that resolution isn't everything, noise can be
more important.

Jon Nadelberg wrote:
dylan wrote:
[]
The 5D has 12.8MPs


Oh, ok. So, 12.8 MPs.

So the density of pixels is about the same, just a bigger area.

I guess I'm just trying to see where MP counts come in when you have a
different sensor size. Since the 5D has such a larger sensor, then
the 12.8 MP would not be equivalent in resolution to a 12.8 MP camera
with a smaller sensor, such as a D2X (not that I'm about to buy
that....).
Also, if the pixel size is a bit larger, how does that affect
resolution? I would think a larger pixel size would reduce
resolution, but probably not where it is really noticeable.

In the final image, viewed at a constant size, the number of pixels
affects the apparent quality of the image as perceived by the viewer. So
the same scene taken with a 6MP sensor would not look as sharp as with a
12MP sensor, but you may need to hold the print quite close to see this
(depending on the print size).

As the 5D has larger pixels, when using the same lens each pixel will have
a larger angular subtense and so cover a greater area of the scene. Each
pixel subtense is a lower spatial frequency, and therefore be working in a
region of the MTF curve for the lens nearer to the left side, perhaps
where the MTF is higher. Therefore, the 5D's pixels should be less
reliant on lenses with an extended MTF, so the lens should be less of a
limiting factor in terms of image resolution.

Of course, the trade-off for the lower resolution is the wider angular
field of view of the image with a given lens. There is another effect as
well independant of lens. Rays of light near the edge of the sensor
arrive at a greater angle of incidence than those at the centre. In a
full-frame sensor the angle of arrival is greater than in a smaller sensor
(for the same lens), and this makes it more difficult for the sensor to
respond correctly. It remains to be seen how well Canon have dealt with
this problem.

David