Digital quality (vs 35mm): Any real answers?

"scott" wrote:
"Zebedee" wrote in message

Just why would anybody print at more than 150dpi when that's the
maximum the eye can see?

Rubbish! It depends how closely you look at the image. My phone has
180dpi
display, and it is pretty easy to see the individual pixels. A 250dpi
display looks *much* smoother. I guess the same goes for prints.

Exactly.

At A4, 1Ds images (320 dpi or so) look a lot better than 6MP images (240
dpi). A lot. The 1Ds is getting close to what I consider "photographic
quality" at A4, neither 6MP nor 35mm are even in the ballpark.

(To repeat my standard rant: we've set the bar too low by looking at that
inferior subminiature format known as 35mm.)

David J. Littleboy
Tokyo, Japan

(Michael Scarpitti) wrote in
om:

All you need to know is: Digital images suck.

**That** is an enlightening answer. Of course, digital
images suck - big time - and so do all photos. They are
not real images - real images shall be made by hand with
brush and oil colors on canvas. Anything less is just
fake and can not really be called images at all.

Sorry - could not resist


/Roland

(Michael Scarpitti) wrote in
om:

All you need to know is: Digital images suck.

**That** is an enlightening answer. Of course, digital
images suck - big time - and so do all photos. They are
not real images - real images shall be made by hand with
brush and oil colors on canvas. Anything less is just
fake and can not really be called images at all.

Sorry - could not resist


/Roland

"Sabineellen" wrote:
David J. Littleboy wrote:
20x24 is a pitiful joke from 35mm B&W films, even Tech Pan. If one has
any
sense of quality imaging at all, 11x14 is MF (645) territory. 20x24 from
6x7
would be OK, but would look better if you used LF.

Where would the dSLRs fit into this?

What Chris said. To my eye, 1Ds images look a lot better at A4 than 6MP
images.

David J. Littleboy
Tokyo, Japan

Toralf wrote in news:cdrkv0$545
:

OK. I've been thinking a bit about the "luminance" argument that has
popped up a number of times (but not a lot, so I may have overlooked
something), and I'm not sure I'm convinced - although it depends a bit
on how you see it.
... snipped away the rest ...

Your analysis is correct. You cannot detect the color of a small
dot that is just one pixel large with a Bayer sensor. If you have
a Foveon sensor you can. The hue resolution is much higher for
a Foveon (or any other senor that detects all color at each point)
than for Bayer sensor.

But ... that is not as important as it first sounds. To understand
why not there are two things you have to consider:

1. Sampling theory
2. Human vision

Sampling theory states that you must filter away all frequencies
at half the sampling frequency and higher to be able to make an
accurate reproduction of the incoming signal. This filter is
called an anti alias filter and it smooths the incoming signal over
nearby detectors, thus removing the problem with single pixel input.
You simply don't have any single pixel input to detect in the first
place. Some choose to call this a blur filter And - in some sense
it is - but it is neccessary to avoid strange artefacts in the picture.
If you have a sharp lens that is well focussed, you se lots of strange
things in a picture taken without an anti alias filter, e.g. a Sigma
camera.

Human vision has very poor color resolution. So - your example with
single dots of another color is not relevant for photographs.
If you want to make abstract pictures, where hue is translated into
luminosity - then it matters though.


/Roland

Toralf wrote in news:cdrkv0$545
:

OK. I've been thinking a bit about the "luminance" argument that has
popped up a number of times (but not a lot, so I may have overlooked
something), and I'm not sure I'm convinced - although it depends a bit
on how you see it.
... snipped away the rest ...

Your analysis is correct. You cannot detect the color of a small
dot that is just one pixel large with a Bayer sensor. If you have
a Foveon sensor you can. The hue resolution is much higher for
a Foveon (or any other senor that detects all color at each point)
than for Bayer sensor.

But ... that is not as important as it first sounds. To understand
why not there are two things you have to consider:

1. Sampling theory
2. Human vision

Sampling theory states that you must filter away all frequencies
at half the sampling frequency and higher to be able to make an
accurate reproduction of the incoming signal. This filter is
called an anti alias filter and it smooths the incoming signal over
nearby detectors, thus removing the problem with single pixel input.
You simply don't have any single pixel input to detect in the first
place. Some choose to call this a blur filter And - in some sense
it is - but it is neccessary to avoid strange artefacts in the picture.
If you have a sharp lens that is well focussed, you se lots of strange
things in a picture taken without an anti alias filter, e.g. a Sigma
camera.

Human vision has very poor color resolution. So - your example with
single dots of another color is not relevant for photographs.
If you want to make abstract pictures, where hue is translated into
luminosity - then it matters though.


/Roland

Toralf writes:

Stephen H. Westin wrote:
"William Graham" writes:
snip

That means a 24 x 36 mm sensing plane would need about 12 megapixels to have
the same resolution as film. Digital cameras are not too far from that
now....Perhaps in another couple of years..........
Huh? The Kodak almost-14MP DCS Pro 14n shipped over a year ago. And
the DCS Pro SLR/n has replaced it, using an improved sensor.
I think he meant *affordable* cameras with that many pixels.

That's a problem. If you want a full 23x36mm sensor, it will be
expensive. Producing that size of chip is just plain expensive. Not
only do you not get many from each silicon wafer, but yield is low. A
Kodak guy said a few years back that the yield is on the order of one
over some power of the area, and the exponent was greater than 2. So a
chip twice as big will probably have a yield of less than a quarter
that of the smaller chip.

I've actually been thinking when that it's when we get there that
I'll buy a digital SLR.

Yeah, but with pros, the savings on film and processing can pay for a
good digital camera pretty quickly.

Also, *maybe* somewhere around that range the
"megapixel" race will slow down a bit, and perhaps then a new camera
won't be obsolete after about two months...

BTW. Do you know more about this sensor? It is full-frame, right? I'm
really interested in knowing if they have resolved the problems that
have lead to the use of smaller sensors so far.

The basic problem is cost. Kodak makes a 22MP CCD that's 38x50mm. It
just costs a lot, and requires a lot of power.

The Kodak full-frame cameras have been plagued with a sensitivity to
incident angle, but that seems to be corrected in firmware pretty well
these days. They explicitly do *not* use microlenses; the thought is
that microlenses will aggravate any angle-of-incidence sensitivity.

These cameras actually don't use a Kodak sensor; instead, they buy
from a Belgian company called FillFactory. It's a CMOS sensor, but one
with tricks to increase the effective fill factor for less aliasing,
better sensitivity, etc. See http://www.fillfactory.com/ for more
about the company. They don't fabricate the chips. The first
generation was made in Israel (!), but now they come from the U.K.

It uses
Nikon-mount lenses, and there is a Canon-mount sibling, the
SLR/c. Several people are using these in lieu of medium-format film
equipment, as they feel the image quality is better.
And medium-format backs reached 16MP some years ago; the best
current
single-shot backs have 22MP.
Oh, and I'm waiting for that that, too, on a 35mm-format camera (as
I've mentioned already),
or at least dreaming about it. A replaceable back, that is. Not
necessarily a system that
would allow you to switch between digital and film, but something that
would give you more flexibility in the sensor department somehow.

Ah, but the sensor needs electronics to keep up with it (data paths,
DSP, etc.) So your replaceable back now costs far more than the body
it goes on. Not to mention the packaging and reliability challenges.

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.

Toralf writes:

Stephen H. Westin wrote:
"William Graham" writes:
snip

That means a 24 x 36 mm sensing plane would need about 12 megapixels to have
the same resolution as film. Digital cameras are not too far from that
now....Perhaps in another couple of years..........
Huh? The Kodak almost-14MP DCS Pro 14n shipped over a year ago. And
the DCS Pro SLR/n has replaced it, using an improved sensor.
I think he meant *affordable* cameras with that many pixels.

That's a problem. If you want a full 23x36mm sensor, it will be
expensive. Producing that size of chip is just plain expensive. Not
only do you not get many from each silicon wafer, but yield is low. A
Kodak guy said a few years back that the yield is on the order of one
over some power of the area, and the exponent was greater than 2. So a
chip twice as big will probably have a yield of less than a quarter
that of the smaller chip.

I've actually been thinking when that it's when we get there that
I'll buy a digital SLR.

Yeah, but with pros, the savings on film and processing can pay for a
good digital camera pretty quickly.

Also, *maybe* somewhere around that range the
"megapixel" race will slow down a bit, and perhaps then a new camera
won't be obsolete after about two months...

BTW. Do you know more about this sensor? It is full-frame, right? I'm
really interested in knowing if they have resolved the problems that
have lead to the use of smaller sensors so far.

The basic problem is cost. Kodak makes a 22MP CCD that's 38x50mm. It
just costs a lot, and requires a lot of power.

The Kodak full-frame cameras have been plagued with a sensitivity to
incident angle, but that seems to be corrected in firmware pretty well
these days. They explicitly do *not* use microlenses; the thought is
that microlenses will aggravate any angle-of-incidence sensitivity.

These cameras actually don't use a Kodak sensor; instead, they buy
from a Belgian company called FillFactory. It's a CMOS sensor, but one
with tricks to increase the effective fill factor for less aliasing,
better sensitivity, etc. See http://www.fillfactory.com/ for more
about the company. They don't fabricate the chips. The first
generation was made in Israel (!), but now they come from the U.K.

It uses
Nikon-mount lenses, and there is a Canon-mount sibling, the
SLR/c. Several people are using these in lieu of medium-format film
equipment, as they feel the image quality is better.
And medium-format backs reached 16MP some years ago; the best
current
single-shot backs have 22MP.
Oh, and I'm waiting for that that, too, on a 35mm-format camera (as
I've mentioned already),
or at least dreaming about it. A replaceable back, that is. Not
necessarily a system that
would allow you to switch between digital and film, but something that
would give you more flexibility in the sensor department somehow.

Ah, but the sensor needs electronics to keep up with it (data paths,
DSP, etc.) So your replaceable back now costs far more than the body
it goes on. Not to mention the packaging and reliability challenges.

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.

In article ,
Roland Karlsson wrote:

(Michael Scarpitti) wrote in
om:

All you need to know is: Digital images suck.

**That** is an enlightening answer. Of course, digital
images suck - big time - and so do all photos. They are
not real images - real images shall be made by hand with
brush and oil colors on canvas. Anything less is just
fake and can not really be called images at all.

Finally, *somebody* gets it right.

/technogrouch_mode

(Stephen H. Westin) writes:

Toralf writes:

Stephen H. Westin wrote:
"William Graham" writes:
snip

That means a 24 x 36 mm sensing plane would need about 12 megapixels to have
the same resolution as film. Digital cameras are not too far from that
now....Perhaps in another couple of years..........
Huh? The Kodak almost-14MP DCS Pro 14n shipped over a year ago. And
the DCS Pro SLR/n has replaced it, using an improved sensor.
I think he meant *affordable* cameras with that many pixels.

That's a problem. If you want a full 23x36mm sensor, it will be
expensive. Producing that size of chip is just plain expensive. Not
only do you not get many from each silicon wafer, but yield is low. A
Kodak guy said a few years back that the yield is on the order of one
over some power of the area, and the exponent was greater than 2. So a
chip twice as big will probably have a yield of less than a quarter
that of the smaller chip.

Yep, the bigger sensor gets *lots* more expensive fast.

Looking at the Kodak DCS Pro 14n, I seem to remember it costing $4k a
year or so ago. That's pretty affordable. Let's see, I'd call it
equivalent in price to 200 rolls of film in professional use (i.e. not
1-hour lab develop-only processing). Which is to say that, for
professional use, it's *free*.
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/