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I put a chart on http://sigmasd10.com that shows the differences in
resolution and actual sensor size of various digital SLRs. I have reproduced
it below (use mono-spaced font).

Model Megapixels Sensor Size (mm)
-------------------------------------------------
Sigma SD-9, SD-10 3.4 21x14 (58% of full frame)
Nikon D2H 4 24x16 (67% of full frame)
Olympus E1 5 18x14 "4/3"
Canon EOS-300D 6 23x15
Canon EOS-10D 6 23x15
Nikon D70 6 24x16 (67% of full frame)
Nikon D100 6 24x16 (67% of full frame)
Fuji S3 Pro 6 23x16
Pentax *ist D 6 24x16 (67% of full frame)
Canon EOS-1D Mark II 8.2 29x19 (80% of full frame)
Canon EOS-1Ds 11 36x24 (full frame)
Kodak DCS SLR/n 13.5 36x24 (full frame)
Kodak DCS SLR/c 13.5 36x24 (full frame)

For reference, the APS frame size is 30x17 mm

The number of megapixels relates directly to picture quality and the ability
to do large enlargements. For very large enlargements (> 8 x10) you'll want
to choose a camera with at least 6 Mp. For professional work that requires
20"x30" enlargements you'll want at least 8 Mp.

Sensor size also matters. The cheaper cameras use smaller sensors, cramming
more pixels into a smaller area, because these are less expensive to
manufacture. You get more sensors per wafer when you have a smaller sensor
size.

Ironically, the larger geometry fabrication processes can yield lower noise
sensors. One reason for the noise issues on the Sigma cameras, is that the
Foveon sensor is fabricated with relatively small geometry (0.18 micron).
Contrast this with the Pentium IV which is fabricated with 90 nm and 0.13
micron technology, and the Foveon sensor seems to use a large geometry. But
compare it with the fabrication technology used by Canon and Nikon, and the
Foveon X3 uses a much smaller geometry.

You have to strike a balance between megapixels and noise. Kodak boasts a
13.5 Mp sensor, but the noise levels make it less desirable than the 11 Mp
sensor in the Canon EOS-1Ds. OTOH, the relatively noisy Foveon X3 sensor
proves that a lower megapixel sensor can still be made to have a lot of
noise.

Ideally, we'll see more full-frame sensors, rather than going to smaller
geometries. We've seen what happens when the number of megapixels is
increased without going to a larger sized sensor (by going to smaller
pixels). But the cost difference of full frame sensors, versus smaller
sensors such as used by Foveon, is significant.

The 4/3 idea is very disturbing. If it takes hold, it will mean a sharp
distinction between professional level D-SLRs and amateur and Prosumer level
D-SLRS. One good thing about Canon, is that they tend to let their higher
end technology percolate down into their lower cost products, after a while.

In article <1dYoc.19654$ .net>,
"Steven M. Scharf" <> wrote:

> The number of megapixels relates directly to picture quality and the ability
> to do large enlargements.

This is not entirely true. not all megapixels are created equal. For
example, when shooting at F2.8 with a wideangle on the 1Ds, the corners
will have very little actual image information. A very good F8 shot with
a 6MP camera might contain more image detail in the corners. ( and with
the E-1, F2.8 performance is already disturbingly good...)

Same with scanning; I find that my normal 4000dpi 35mm scans at about
18MP, have similar amount of image-detail as a 6MP digital capture. Of
course the scans are much bigger, but they don't contain much more
"image". (a bit more, depending on the film used)

To double image resolution you need 4 times as many megapixels. the
difference between 5 and 8MP isn't that large. More is better, I agree
with that, but the total picture just isn't that simple. A good 5MP will
beat a 8MP with a lousy lens anytime.

> The 4/3 idea is very disturbing. If it takes hold, it will mean a sharp
> distinction between professional level D-SLRs and amateur and Prosumer level
> D-SLRS.

??? Please explain...
I have created images (professionally) with a 1Ds, D1x, and E-1, and I
fail to see this sharp distinction.

Lourens

True, the Canon is better all round than the Kodak but
it depends what you want to do with the camera. The Kodak
displays no noise at ISO 80 and, as it has no microlenses,
has minimal chromatic aberration. For landscapes, the Kodak
is unbeatable at the moment.

Graham

"Steven M. Scharf" <> wrote in message
news:1dYoc.19654$ link.net...
>
> You have to strike a balance between megapixels and noise. Kodak boasts a
> 13.5 Mp sensor, but the noise levels make it less desirable than the 11 Mp
> sensor in the Canon EOS-1Ds. OTOH, the relatively noisy Foveon X3 sensor
> proves that a lower megapixel sensor can still be made to have a lot of
> noise.
>

"when shooting at F2.8 with a wideangle on the 1Ds, the corners
will have very little actual image information. A very good F8 shot with
a 6MP camera might contain more image detail in the corners."

Can you explain a bit more, are you saying a 35mm frame doesn't have detail
in the corners ?

Thanks

"Lourens Smak" <> wrote in message
news:smak-...
> In article <1dYoc.19654$ .net>,
> "Steven M. Scharf" <> wrote:
>
> > The number of megapixels relates directly to picture quality and the
ability
> > to do large enlargements.
>
> This is not entirely true. not all megapixels are created equal. For
> example, when shooting at F2.8 with a wideangle on the 1Ds, the corners
> will have very little actual image information. A very good F8 shot with
> a 6MP camera might contain more image detail in the corners. ( and with
> the E-1, F2.8 performance is already disturbingly good...)
>
> Same with scanning; I find that my normal 4000dpi 35mm scans at about
> 18MP, have similar amount of image-detail as a 6MP digital capture. Of
> course the scans are much bigger, but they don't contain much more
> "image". (a bit more, depending on the film used)
>
> To double image resolution you need 4 times as many megapixels. the
> difference between 5 and 8MP isn't that large. More is better, I agree
> with that, but the total picture just isn't that simple. A good 5MP will
> beat a 8MP with a lousy lens anytime.
>
> > The 4/3 idea is very disturbing. If it takes hold, it will mean a sharp
> > distinction between professional level D-SLRs and amateur and Prosumer
level
> > D-SLRS.
>
> ??? Please explain...
> I have created images (professionally) with a 1Ds, D1x, and E-1, and I
> fail to see this sharp distinction.
>
> Lourens

In article <X85pc.368$cJ4.330@newsfe1-win>,
"dylan" <> wrote:

> Can you explain a bit more, are you saying a 35mm frame doesn't have detail
> in the corners ?

No but some lenses (most wides actually) are quite soft in the corners
and most suffer from severe light fall-off too at wide apertures. The
difference can be as big as 2 stops between center and corner.
Obviously, both these effects makes one lose detail.
For example the 16-35 L lens from Canon isn't very good at F2.8 in the
corners, (dark, soft and lack of contrast) and the quality-difference
from center to corner is really huge at 16mm/F2.8

With telephoto things are a bit different but many tele-zooms do have
light fall-off. Sharpness is usually better across the entire frame.
(with less degradation towards the corners)

Of course, shooting at F8 will be better but usually this isn't an
alternative because of the light-level. And if you can use the 6MP @ F8,
you could also use an 11MP camera @ F8...


Lourens

Thanks for your explanation.

I would say the 'No' at the beginning should be 'Yes' because you are saying
the corners do have less detail with wide-angles when covering a 35mm frame,
particularly at wide aperture

Cheers


"Lourens Smak" <> wrote in message
news:smak-...
> In article <X85pc.368$cJ4.330@newsfe1-win>,
> "dylan" <> wrote:
>
> > Can you explain a bit more, are you saying a 35mm frame doesn't have
detail
> > in the corners ?
>
> No but some lenses (most wides actually) are quite soft in the corners
> and most suffer from severe light fall-off too at wide apertures. The
> difference can be as big as 2 stops between center and corner.
> Obviously, both these effects makes one lose detail.
> For example the 16-35 L lens from Canon isn't very good at F2.8 in the
> corners, (dark, soft and lack of contrast) and the quality-difference
> from center to corner is really huge at 16mm/F2.8
>
> With telephoto things are a bit different but many tele-zooms do have
> light fall-off. Sharpness is usually better across the entire frame.
> (with less degradation towards the corners)
>
> Of course, shooting at F8 will be better but usually this isn't an
> alternative because of the light-level. And if you can use the 6MP @ F8,
> you could also use an 11MP camera @ F8...
>
>
> Lourens

"Lourens Smak" <> wrote in message
news:smak-...
> In article <X85pc.368$cJ4.330@newsfe1-win>,
> "dylan" <> wrote:
>
> > Can you explain a bit more, are you saying a 35mm frame doesn't have
detail
> > in the corners ?
>
> No but some lenses (most wides actually) are quite soft in the corners
> and most suffer from severe light fall-off too at wide apertures. The
> difference can be as big as 2 stops between center and corner.
> Obviously, both these effects makes one lose detail.

So stop down. And compare the same angle of view. Talking about "losing
detail" seems odd: the E-1/10D can't do a 16mm equivalent at f/2.8. The
E-1's widest is 22mm, and the 10D with the 12-24 is a 19.5mm f/4.5 lens that
needs to be stopped down quite a bit. Since none of these cameras gets
anywhere near 16mm, however bad the 1Ds is at 16mm, it's infinitely better
than the E-1/10D.

By the way, I bet the E-1's 11-22 is a mess in the corners at 11mm and
f/2.8.

> For example the 16-35 L lens from Canon isn't very good at F2.8 in the
> corners, (dark, soft and lack of contrast) and the quality-difference
> from center to corner is really huge at 16mm/F2.8

So? The widest lens for the E-1 is 22m: the 11-22mm zoom. I bet that with
both at f/2.8, with the E-1 at 11mm and the Canon at 22mm, If you made A4
prints from both, the Canon would be significantly better than the E-1. Even
at the corners.

In any reasonable comparison (same angle of view, same f stop), the 1Ds is
going to capture more detail than either the E-1 or a 6MP dSLR. If
performance flags in places the E-1/10D can't even go, you're still way
ahead.

> With telephoto things are a bit different but many tele-zooms do have
> light fall-off. Sharpness is usually better across the entire frame.
> (with less degradation towards the corners)
>
> Of course, shooting at F8 will be better but usually this isn't an
> alternative because of the light-level.

No, that's the cup half-empty approach. You should be glad you've got f/2.8
even if it's funky, because there are a lot of images that don't depend on
the corners. (I'm thinking of buying a fixed-lens camera with a 28mm
equivalent lens that's only f/5.6.)

>And if you can use the 6MP @ F8,
> you could also use an 11MP camera @ F8...

Yes. The "lose detail" concept is bogus.

David J. Littleboy
Tokyo, Japan

Hello Steven

Excellent post.

One note Re: your chart: your sensor size column
percentages might be a bit misleading, on the large
side, for folks. That's because you're giving percentages
along just one dimension of the sensor, rather than
the area of each sensor. For example, the Nikon D70 sensor,
at 24x16, is (24/36)*(16/24) = 4/9, or approx. 44% of full frame,
not 67%.

-- stan

David J. Littleboy <> wrote:

> By the way, I bet the E-1's 11-22 is a mess in the corners at 11mm and
> f/2.8.

You'd lose that bet.

> So? The widest lens for the E-1 is 22m: the 11-22mm zoom.

The 8-16mm is due out this year, probably at Photokina.

BTW the so-called 6mp cameras crop to the same or smaller than the 5 mp
E-1 on most paper sizes.

"dylan" <> wrote in message news:<X85pc.368$cJ4.330@newsfe1-win>...
> "when shooting at F2.8 with a wideangle on the 1Ds, the corners
> will have very little actual image information. A very good F8 shot with
> a 6MP camera might contain more image detail in the corners."
>
> Can you explain a bit more, are you saying a 35mm frame doesn't have detail
> in the corners ?

The smaller the sensor the better, provided it takes 35mm format
lenses, because optically the lens is dramatically better in the
middle. Wiegh that consideration with the total sensor count,
obviously optical pixels is better. That is why Sigma, having both
the highest number of optical pixels (interpolation is meaningless,
only optical MPs matter) and the smallest sensor size, is several
steps ahead of anything offered by any other manufacturer.

The Kodak 14n (3.3MP optical; 13.5MP interpolated) has almost as many
MPs as the Sigma SDs (3.43 optical; 13.72MP interpolated), but it is
full frame which is makes the optical quality totally unacceptable by
comparison. Assuming the same MPs even the optical resolution over
the respective image areas, croppers are dramatically better cameras.

IOWs, Sigma builds the only pro quality DSLRs currently available.