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

MXP wrote:
I was surprised how good prints from 35mm Gigabilfilm looked.
I made 20x30cm. No grains at all and super sharp even with a x15 magnifier
directly on
the print. I think more people should try this film.

Very sharp and smooth 20x30CM (or more usually 24x30cm) prints is NORMAL
with just about any non-high speed B&W film, not just Gigabit.

Chris

"TP" wrote in message
news
"Justin Thyme" wrote:

Exactly - I don't understand why the constant desire for 35mm full frame
sensors.


It is because people with collections of lenses for 35mm SLRs want to
be able to use them on digital SLRs without a change of angle of view.
The reduced angle of view is actually what does allow the use of film lenses
on digital - especially at wide angle. Film doesn't mind if the light hits
it at a fairly substantial angle, and on wide angle lenses it does. Digital
sensors OTOH need the light to hit fairly straight on. If light hits at a
substantial angle, less reaches the actual sensor. As a result at very wide
angles with a film lens and a digital sensor, there is substantial
vignetting. This can be countered to some extent by putting micro-lenses on
the sensor but the result is a compromise at best. Digital designed lenses
OTOH are made to project the light onto the sensor at a more square angle.
Considering film lenses don't work as well on digital, to me it makes more
sense to accept the narrower field of view with your existing lenses, and
add a short focal length lens designed for digital to make up the difference
at the wide angles. Considering Canon, Nikon and Pentax all bundle
wide-angle digital lenses with their bodies, this makes up the shortfall
quite nicely.

"TP" wrote in message
news
"Justin Thyme" wrote:

Exactly - I don't understand why the constant desire for 35mm full frame
sensors.


It is because people with collections of lenses for 35mm SLRs want to
be able to use them on digital SLRs without a change of angle of view.
The reduced angle of view is actually what does allow the use of film lenses
on digital - especially at wide angle. Film doesn't mind if the light hits
it at a fairly substantial angle, and on wide angle lenses it does. Digital
sensors OTOH need the light to hit fairly straight on. If light hits at a
substantial angle, less reaches the actual sensor. As a result at very wide
angles with a film lens and a digital sensor, there is substantial
vignetting. This can be countered to some extent by putting micro-lenses on
the sensor but the result is a compromise at best. Digital designed lenses
OTOH are made to project the light onto the sensor at a more square angle.
Considering film lenses don't work as well on digital, to me it makes more
sense to accept the narrower field of view with your existing lenses, and
add a short focal length lens designed for digital to make up the difference
at the wide angles. Considering Canon, Nikon and Pentax all bundle
wide-angle digital lenses with their bodies, this makes up the shortfall
quite nicely.

Justin Thyme wrote:
"TP" wrote in message
news
"Justin Thyme" wrote:

Exactly - I don't understand why the constant desire for 35mm full frame
sensors.


It is because people with collections of lenses for 35mm SLRs want to
be able to use them on digital SLRs without a change of angle of view.

The reduced angle of view is actually what does allow the use of film lenses
on digital - especially at wide angle. Film doesn't mind if the light hits
it at a fairly substantial angle, and on wide angle lenses it does. Digital
sensors OTOH need the light to hit fairly straight on. [ ... ]
Exactly. But isn't this a problem that ought to be solved, or a
limitation that ought to be overcome?


substantial angle, less reaches the actual sensor. As a result at very wide
angles with a film lens and a digital sensor, there is substantial
vignetting. This can be countered to some extent by putting micro-lenses on
the sensor but the result is a compromise at best. Digital designed lenses
OTOH are made to project the light onto the sensor at a more square angle.
Isn't that trying to solve a sensor problem a the lens end? Seems like
the wrong way to go about it, at least from a philosophical view-point.
(It's probably also the only know way, right now, but I don't see it as
a good permanent solution.)

Also, don't larger sensors advances in their own right? I mean, in terms
of light sensitivity etc.
Considering film lenses don't work as well on digital, to me it makes more
sense to accept the narrower field of view with your existing lenses, and
add a short focal length lens designed for digital to make up the difference
at the wide angles. Considering Canon, Nikon and Pentax all bundle
wide-angle digital lenses with their bodies, this makes up the shortfall
quite nicely.

Justin Thyme wrote:
"TP" wrote in message
news
"Justin Thyme" wrote:

Exactly - I don't understand why the constant desire for 35mm full frame
sensors.


It is because people with collections of lenses for 35mm SLRs want to
be able to use them on digital SLRs without a change of angle of view.

The reduced angle of view is actually what does allow the use of film lenses
on digital - especially at wide angle. Film doesn't mind if the light hits
it at a fairly substantial angle, and on wide angle lenses it does. Digital
sensors OTOH need the light to hit fairly straight on. [ ... ]
Exactly. But isn't this a problem that ought to be solved, or a
limitation that ought to be overcome?


substantial angle, less reaches the actual sensor. As a result at very wide
angles with a film lens and a digital sensor, there is substantial
vignetting. This can be countered to some extent by putting micro-lenses on
the sensor but the result is a compromise at best. Digital designed lenses
OTOH are made to project the light onto the sensor at a more square angle.
Isn't that trying to solve a sensor problem a the lens end? Seems like
the wrong way to go about it, at least from a philosophical view-point.
(It's probably also the only know way, right now, but I don't see it as
a good permanent solution.)

Also, don't larger sensors advances in their own right? I mean, in terms
of light sensitivity etc.
Considering film lenses don't work as well on digital, to me it makes more
sense to accept the narrower field of view with your existing lenses, and
add a short focal length lens designed for digital to make up the difference
at the wide angles. Considering Canon, Nikon and Pentax all bundle
wide-angle digital lenses with their bodies, this makes up the shortfall
quite nicely.

(George Preddy) wrote in
om:

Sigma cameras do NOT sample color. They are the worlds only direct
image sensors. Phenomenally better per pixel image quality than Leaf,
but slightly lower resolution at only 13.72MP.

Of course they are sampling. Why do you insist in this nonsens?
And why do you insist in multiplying the number of pixels with 4?
Even Foveon only multiplies with 3. Why lie even worse than Foveon?

camera.

Human vision has very poor color resolution.

If that was true than no one couldn't see the difference in either of
these scientific test images, where the 13.72MP Foveon displays more
than double the full color resoution of the 6MP Canon 10D ...

What kind of resolution do the Sigma detect in the area 14-20? Do
you really think that the test chart has fewer lines there? Or
might that be an effect of not using any anti alias filter?

Why is the vertical white line straight in the Bayer pictures
and why does it wander back and forth in the Sigma picture?
Might this also be due to the lack of an anti alias filter?
Or do you think they have made such a line on the test chart
and the Sigma is the only one that can resolve it?

Why is the Sigma picture so grainy? According to other posts
here by you, the Sigma has superior performance regarding grain.

How come that the 10D picture looks so unsharp? It looks unsharp
even in the black to gray transitions. The 10D can do much better
than that. Might there be a mistake here in the testing procedure?

Questions George. Have you any answers?


/Roland

(George Preddy) wrote in
om:

Sigma cameras do NOT sample color. They are the worlds only direct
image sensors. Phenomenally better per pixel image quality than Leaf,
but slightly lower resolution at only 13.72MP.

Of course they are sampling. Why do you insist in this nonsens?
And why do you insist in multiplying the number of pixels with 4?
Even Foveon only multiplies with 3. Why lie even worse than Foveon?

camera.

Human vision has very poor color resolution.

If that was true than no one couldn't see the difference in either of
these scientific test images, where the 13.72MP Foveon displays more
than double the full color resoution of the 6MP Canon 10D ...

What kind of resolution do the Sigma detect in the area 14-20? Do
you really think that the test chart has fewer lines there? Or
might that be an effect of not using any anti alias filter?

Why is the vertical white line straight in the Bayer pictures
and why does it wander back and forth in the Sigma picture?
Might this also be due to the lack of an anti alias filter?
Or do you think they have made such a line on the test chart
and the Sigma is the only one that can resolve it?

Why is the Sigma picture so grainy? According to other posts
here by you, the Sigma has superior performance regarding grain.

How come that the 10D picture looks so unsharp? It looks unsharp
even in the black to gray transitions. The 10D can do much better
than that. Might there be a mistake here in the testing procedure?

Questions George. Have you any answers?


/Roland

Roland Karlsson wrote:
Toralf wrote in
:


Hi.


Hi self - now - it is obvious from your post that you
have not been hanging around here so long.
No not really. I was sort of away from photography for a long while -
although I've been messing around with other sorts of digital imaging,
like I said.

This is the
favourite topic that pops up now and then. From that
perspective - your questions are more than valid.


I'm still wondering about how good the image quality of modern digital
cameras (especially SLRs) really is, in particular how it compares
with 35mm film. I've seen many articles on the subject on the Net, but
few of them seem to give you a lot of tangible information (I want to
see the numbers, please), and I can't help feeling that tests they
refer to are usually done to prove a point, i.e. that digital cameras
are as good as 35mm, which is not the way you do proper research.


Proper research? hmmm .... I don't think it is reasonable to expect
that anyone starts some kind of proper research on this topic. Film
is the old medium - digital is the new - gradually one will diminish
and the other take over. If any comparisons is biased or not does not
matter the slightest. Oh - I understand that you want to know, and I
want to know and lots of people wants to know. But proper research is
not just something done because some wants to know.

On the other hand I think you have missed that some really nice
comparisons have been made. Lots of references can be found in old
topics in this forum.
Possibly. There is so much out there, and most of is is complete nonsense.

That comment is valid for the Internet in general, of course.


1. What is the resolution of a 35mm film anyway? I think I read
somewhere that a colour negative is at least 3000dpi. Is that
correct? How about black&white? (Yeah I know, a film doesn't have
pixels in exactly the same sense as a digital image, but it *is* made
up of discrete elements after all.)


I think it is rather safe to say that 35 mm film is at most 20 Mpixels
with regards to resolution. But ... before that you start to see grain.
If you like the grainy look, thats just perfect. If you don't, then maybe
6 Mpixels or so gives you grain free pictures from the very best 35 mm
films.

I also think it is rather safe to say that at higher ISO, film just
have to give away for DSLR cameras.


2. What about the print? 300dpi?


Hmm ... yes what about it?
Is it?

What I meant to ask was, it is fair to assume that a "standard" print is
roughly 300dpi?

It all depends on the viewing distance and your demands.



[ snip ]

No comparison possible IMHO. The Bayer computation is not equal
to interpolation. Interpolation is only used to extract color
information. The direct values are used for luminosity - no
interpolation is made for luminosity.
It seems to me this isn't entirely true. But I've

5. And how about those other parameters I mentioned briefly above -
like different kinds of geometric distortions, noise, flat field bias
etc.? Can those be compared with the ones of plain old film?


Yes - but are those not lens properties?
I was referring to the inaccuracies introduced by the sensor (or film)
itself. There are lens properties that give similar results, but those
aren't the ones I was talking about.

For instance, a CCD may have geometric distortions because the
individual sensors aren't accurately positioned, flat field bias because
the sensors don't have the same sensitivity etc. But maybe I wasn't
using the right terms here. For instance, I said "flat-field bias"
because the process used to eliminate it is usually known as "flat-field
correction." It is related to the process of "light calibration", which
I think may be what's referred to as "white balance" when talking about
digital photo cameras.



6. And the chromic aberration effects? How serious are they these
days? And are the full-frame sensors that are actually found in some
high-end cameras now, in any way comparable to film in that respect?


Same here - those are lens properties.
Same hear, nearly. I was trying to ask about how the sensors are
influenced by "lens errors". Film and CCD/CMOS etc. aren't in the same
way, I think.


Well, maybe some people will say I have a somewhat critical or
conservative attitude towards digital cameras, but I actually think
you ought to be a bit sceptical when something "new and wonderful"
comes a long; new technology is too often introduced for technology's
own sake, IMO.


Ahhh ... you missed that also Digital is not something new and
wonderful. It has been here for a while.
Well, maybe. I haven't checked very closely what photographers have been
doing lately, but I do know that CCD technology is about 30 years old,
and some of the people at work used equipment that might me called
digital cameras in 1983 or something like that (or maybe it was earlier
- I've forgotten the exact dates) so the technology is definitely not
new (but I think maybe the mass-introduction of digital cameras is more
influenced by the advent of high-capacity compact storage media than the
sensor technology development.)

However, I think it is only quite recently that digital cameras became
the fashion for amateurs. Also, "everything digital" has been quite
fashionable for some years, but still is, I think. And in the somewhat
broader sense, digital technology is still perceived as "new" or very
modern.

And - it is rather wonderful.
It has improved life for photographers (IMHO) a lot.

Quite possibly. The difficult bit if you want to assess this technology,

is to sort out the real (good) experiences from all the hype...

Roland Karlsson wrote:
Toralf wrote in
:


Hi.


Hi self - now - it is obvious from your post that you
have not been hanging around here so long.
No not really. I was sort of away from photography for a long while -
although I've been messing around with other sorts of digital imaging,
like I said.

This is the
favourite topic that pops up now and then. From that
perspective - your questions are more than valid.


I'm still wondering about how good the image quality of modern digital
cameras (especially SLRs) really is, in particular how it compares
with 35mm film. I've seen many articles on the subject on the Net, but
few of them seem to give you a lot of tangible information (I want to
see the numbers, please), and I can't help feeling that tests they
refer to are usually done to prove a point, i.e. that digital cameras
are as good as 35mm, which is not the way you do proper research.


Proper research? hmmm .... I don't think it is reasonable to expect
that anyone starts some kind of proper research on this topic. Film
is the old medium - digital is the new - gradually one will diminish
and the other take over. If any comparisons is biased or not does not
matter the slightest. Oh - I understand that you want to know, and I
want to know and lots of people wants to know. But proper research is
not just something done because some wants to know.

On the other hand I think you have missed that some really nice
comparisons have been made. Lots of references can be found in old
topics in this forum.
Possibly. There is so much out there, and most of is is complete nonsense.

That comment is valid for the Internet in general, of course.


1. What is the resolution of a 35mm film anyway? I think I read
somewhere that a colour negative is at least 3000dpi. Is that
correct? How about black&white? (Yeah I know, a film doesn't have
pixels in exactly the same sense as a digital image, but it *is* made
up of discrete elements after all.)


I think it is rather safe to say that 35 mm film is at most 20 Mpixels
with regards to resolution. But ... before that you start to see grain.
If you like the grainy look, thats just perfect. If you don't, then maybe
6 Mpixels or so gives you grain free pictures from the very best 35 mm
films.

I also think it is rather safe to say that at higher ISO, film just
have to give away for DSLR cameras.


2. What about the print? 300dpi?


Hmm ... yes what about it?
Is it?

What I meant to ask was, it is fair to assume that a "standard" print is
roughly 300dpi?

It all depends on the viewing distance and your demands.



[ snip ]

No comparison possible IMHO. The Bayer computation is not equal
to interpolation. Interpolation is only used to extract color
information. The direct values are used for luminosity - no
interpolation is made for luminosity.
It seems to me this isn't entirely true. But I've

5. And how about those other parameters I mentioned briefly above -
like different kinds of geometric distortions, noise, flat field bias
etc.? Can those be compared with the ones of plain old film?


Yes - but are those not lens properties?
I was referring to the inaccuracies introduced by the sensor (or film)
itself. There are lens properties that give similar results, but those
aren't the ones I was talking about.

For instance, a CCD may have geometric distortions because the
individual sensors aren't accurately positioned, flat field bias because
the sensors don't have the same sensitivity etc. But maybe I wasn't
using the right terms here. For instance, I said "flat-field bias"
because the process used to eliminate it is usually known as "flat-field
correction." It is related to the process of "light calibration", which
I think may be what's referred to as "white balance" when talking about
digital photo cameras.



6. And the chromic aberration effects? How serious are they these
days? And are the full-frame sensors that are actually found in some
high-end cameras now, in any way comparable to film in that respect?


Same here - those are lens properties.
Same hear, nearly. I was trying to ask about how the sensors are
influenced by "lens errors". Film and CCD/CMOS etc. aren't in the same
way, I think.


Well, maybe some people will say I have a somewhat critical or
conservative attitude towards digital cameras, but I actually think
you ought to be a bit sceptical when something "new and wonderful"
comes a long; new technology is too often introduced for technology's
own sake, IMO.


Ahhh ... you missed that also Digital is not something new and
wonderful. It has been here for a while.
Well, maybe. I haven't checked very closely what photographers have been
doing lately, but I do know that CCD technology is about 30 years old,
and some of the people at work used equipment that might me called
digital cameras in 1983 or something like that (or maybe it was earlier
- I've forgotten the exact dates) so the technology is definitely not
new (but I think maybe the mass-introduction of digital cameras is more
influenced by the advent of high-capacity compact storage media than the
sensor technology development.)

However, I think it is only quite recently that digital cameras became
the fashion for amateurs. Also, "everything digital" has been quite
fashionable for some years, but still is, I think. And in the somewhat
broader sense, digital technology is still perceived as "new" or very
modern.

And - it is rather wonderful.
It has improved life for photographers (IMHO) a lot.

Quite possibly. The difficult bit if you want to assess this technology,

is to sort out the real (good) experiences from all the hype...

David Dyer-Bennet wrote:
(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).
You, and many other people when discussing these matters, seem to forget
that the storage space necessary for the digital cameras is not free of
charge, though (neither are the prints, even if you have your own printer.)

Actually, it's a lot cheaper than film, if you use something like
CD-ROM, but then there is the cost of transferring the data. Well, maybe
that's analogous to the film development cost... But of course, if you
want to keep the data for any length of time, CD-ROM usually isn't
considered reliable enough in the sense that they deteriorate over time
(and at a rate much higher than for film, I believe) - so you'll have to
use something else (tape?) that's more expensive, or copy the data to
new media from time to time. (For other kinds of archival purposes, this
is done every 5 or 10 years.)

If you'd like to keep the data on the original storage medium, I think
you'll find that the cost is *a lot* higher than for film.

But this is of course assuming you want to keep most of the data in the
first place. Perhaps the most important advantage of digital cameras is
that shots that are complete failures, cost you virtually nothing.

Which is to say that, for
professional use, it's *free*.