FF sensors: is 80MP needed?

frederick wrote:

Roger N. Clark (change username to rnclark) wrote:

Digital
also has much greater dynamic range.


How dare you keep saying that - when believing the reverse is the raison
d'être for the quaint obsession some have for 35mm.


;-)

[A complimentary Cc of this posting was sent to
Roger N. Clark (change username to rnclark)
], who wrote in article :
Irrelevant. You are discussing lens+sensor vs lens+film. I'm
discussing lens+sensor vs lens+ideal_sensor.

Theory is fine, but you must consider all factors.

One can never consider all factors. It is important to consider *key*
factors - of course.

One factor you have not considered, [...] is not just resolution,
but [...]

Since all I was considering was resolution, it is not surprising I did
not consider other factors. ;-) (Especially since I already addressed
"other factors" in my other posts; here I concentrated on some "new"
experiments.)

Digital has a much higher signal-to-noise ratio

Such a blank statement is definitely wrong; you mean the same
exposition, and it is not applicable to my comparison. E.g, with the
current technology digital will give much worse noise than film if the
exposition of digital is 20x smaller than of film ;-). And note that
this is quite probably holds when you compare LF film to FF digital
(but I do not remember the details of the exposition you used...) -
count number of photons per "pixel" (I mean square with size
determined by the MTF curve).

... that greatly influences perceived image detail.

Film has practically no noise when correctly exposed with aperture
f/32 - or much smaller f-number.

Digital also has much greater dynamic range.

IMO, this remains to be proven yet (though I suspect that the proof
*will* support your claim - I just *have not seen* it).

Your investigation is very interesting, but, IMO, it completely missed
the point. Essentially, you measured the noise of 6um square of film
vs 8um square of semiconductor. So, film's noise *at these extremely
high spacial frequencies* turns out to be much more than digital
sensors'; fine. But, as you probably saw it in many posts about your
experiments, it is the noise at much lower spacial frequencies what
many people consider the measure of dynamic range.

So how one could measure "true dynamic range"? Essentially, one
cannot separate dynamic range from resolution; e.g., in each
exposition zone, one could measure the S/N ratio at different spacial
frequencies, and find at which frequency S/N ratio goes above 3 (or
some other reasonable number).

One gets a curve of (thus defined) spacial resolution per degree of
underexposition; *this curve*, IMO, is the measure of dynamic range.

Again: I agree with you that such an investigation will *most
probably* give film much lower mark than digital sensor - but 10x20in
film is practical, and digital is not. BTW, the question I addressed
in my initial posting is also related to this: for which f-numbers
this advantage of film will disappear, since FF digital sensor may
behave as well as HUGE area of film.

Thanks,
Ilya

[A complimentary Cc of this posting was sent to
frederick
], who wrote in article 1160974662.417746@ftpsrv1:
Would you like to qualify your "lack of being impressed" by some
objective measure of your own

Already the second paragraph contains complete BS:

And with that smaller focal length is around a 2.5 times increase
in available depth of field.

Anyone knows that switching formats does not bring any change in DoF -
if one WANTS to produce identical images, one can.

Different formats produce non-identical results only because of
different "effective MP count", and lens quality at the used f-stop
(well, QE may also enter the picture, e.g., when you compare film to
digital). You just use f-stop "proportional" to the formfactor, and
everything else comes out to be identical.

Let me repeat:

The physical laws of scaling are the following: to produce the same
image from N times smaller sensor (linearly) one needs to:

a) have the same count of pixels;

b) have the same QE;

c) have the same readout noise;

d) have the same full well;

e) have the same exposure time;

f) use N times higher aperture (measured as an F-number, e.g., 1/45);

g) have the same "quality" of the lens (e.g, measured as quotient
of actual MTF of the lens to MTF of diffraction-limited lens)

Hope this helps,
Ilya

"Scott W" wrote in message
oups.com...
Matt Clara wrote:
I haven't used 10 mp, so I don't know, but I suspect it would lack
in one
way, and that's the same way the 6-8 mp cameras do: upon enlargement they
begin to break down rather quickly. To me this speaks to overall levels
of
infomation present in the two mediums, but it could be any number of
reasons. Enlargement, of course, isn't the reason digital is eclipsing
35mm, and even there it's good enough for some purposes. I still shoot
my
formals as well as some select other shots with medium-format film
precisely
because it can be blown up poster-size with little detraction to the
image,
provided it's a sharp, well exposed negative, of course.

This seems like a bit of bait and switch to me, you seem to claim that
35mm film is better then an 8 MP DSLR but then you say you are using MF
film. Clearly MF will easily beat an 8 MP DLSR but I have yet to see a
color image from 35mm film that beats a 8 MP DSLR and the vast majority
of 35mm film scans fall far short of a 8 MP DSLR.



You're right Scott, I should have mentioned that I have shot 35mm right
along side digital, plus I used to shoot nothing but 35mm, and 35mm blows up
better. I also think I get more keepers with 35mm, and fewer exposure
problems, but the ability to see those problems with the digital is
priceless and the fact that I don't have to pay for 15 rolls of development
and prints isn't priceless, I can see a very real savings there, though it's
traded for lots of time in front of a computer. As for your inability to
see that 35mm beats digital in most forms today, I suggest you simply don't
have the experience there, or you would. And I'm not talking about scans of
35mm--you don't have to scan it to get the job done, see.

--
Regards,
Matt Clara
www.mattclara.com

Matt Clara wrote:
And I'm not talking about scans of
35mm--you don't have to scan it to get the job done, see.

But scanning is about the only way we have to compare, unless you want
to come to Hawaii with your prints. If you are trying to say that
optical prints show more detail then it should be easy to scan the
optical print.

The best that I have seen by far is a scan Max Perl did and whereas the
35mm shot showed more detail then an 8 MP camera when printed out they
were about the same quality due to the grain in the film scan.

Since I would not do a workflow that does not have the image in a
digital form at some point if it can't be scanned it is not of much
value to me. And since I have yet to see anyone demonstrate that a
workflow that does not scan the film can produce a better image when
when you scan film I am not going to take that on faith.

Scott

David J. Littleboy wrote:


"Greg "_"" wrote:
If you want to use monochrome film - a material that has
incomparably inconvenient performance compared with even the
cheap digital cameras that they now sell at the supermarket

Right smirk :^
yawn.
25 iso monochrome....
zzzzzz

Reasonably few B&W shooting photographers shoot 25 asa BW film on a
consistent, none I know personally.

That's because most of them have been discontinued. Panatomic X and
Tech Pan are history. (I think there's still an Agfa film in
production, though.)

Panatomic-X is the reason I hate 35mm. At 11x14, Plus-X in 645 looks
way better than Panatomic X in 35mm, and is two stops faster. ISO 25
gets real painful when you want to use either a red filter or a
polarizer.

Nowadays, TMX 100 is close to what the ISO 25 films used to be in
terms of grain and resolution, although some people complain they
don't like its tonal rendition. TMX 100 in 6x7 will edge out the 5D,
though.
About 40 or so years ago over a period of a couple of years I used
micro-neg pan developed in Dilute FX1a developer (designed by Geoffrey
W. Crawley and published in BJP) rated at 8asa and although it was slow
the results were pleasing but not for action. The grain could hardly be
seen.

--
Delete l to reply.

Scott W wrote:
Matt Clara wrote:
And I'm not talking about scans of
35mm--you don't have to scan it to get the job done, see.

But scanning is about the only way we have to compare, unless you want
to come to Hawaii with your prints. If you are trying to say that
optical prints show more detail then it should be easy to scan the
optical print.

The best that I have seen by far is a scan Max Perl did and whereas the
35mm shot showed more detail then an 8 MP camera when printed out they
were about the same quality due to the grain in the film scan.

Since I would not do a workflow that does not have the image in a
digital form at some point if it can't be scanned it is not of much
value to me. And since I have yet to see anyone demonstrate that a
workflow that does not scan the film can produce a better image when
when you scan film I am not going to take that on faith.

Scott

I have had plenty of experience with 35mm optical process prints from
negative and transparency - and have a big portfolio of larger
(10x8)prints that I can easily compare. Most of the larger prints I
made from 35mm used Fuji iso 50 and Cibachrome. I always carried two
slr bodies, one loaded with iso50 transparency for enlargements, the
other loaded with iso 200 negative film because iso 50 is practically
useless for handheld shooting in less than ideal light, yet ideal light
is seldom what you want for taking interesting pictures.
Scanned 35mm negative film printed with light-jet leaves the optical
process cibachrome prints in the dust for reproducing detail. Inkjet
prints direct from digital look better again, and are almost infinitely
more convenient.
I really couldn't care less about technical arguments - how the picture
looks is the most important factor. A few years ago, I realised that
snapshots taken from an inexpensive pocket sized 4mp P&S digital were
practically as good as what I could get with iso200 35mm. 35mm film is
dead - there is no point at all now that dslr cameras are affordable.

Ilya Zakharevich wrote:
[A complimentary Cc of this posting was sent to
frederick
], who wrote in article 1160974662.417746@ftpsrv1:
Would you like to qualify your "lack of being impressed" by some
objective measure of your own

Already the second paragraph contains complete BS:

And with that smaller focal length is around a 2.5 times increase
in available depth of field.

Anyone knows that switching formats does not bring any change in DoF -
if one WANTS to produce identical images, one can.

Only when maximum DOF is the objective. Not when shallow DOF is sought.

Different formats produce non-identical results only because of
different "effective MP count", and lens quality at the used f-stop
(well, QE may also enter the picture, e.g., when you compare film to
digital). You just use f-stop "proportional" to the formfactor, and
everything else comes out to be identical.

You have quoted selectively:
"The only downside to my new system is working with depth of field. On
my 4x5 Linhof, I have a focusing gauge that allows me to quickly
determine the optimum f stop for each situation. With the Mamiya and the
zoom lenses, this is much harder to determine. On the plus side, a
composition that required a 200mm on the 4x5 needs only an 80mm for the
P45 sensor. And with that smaller focal length is around a 2.5 times
increase in available depth of field."

That comment "available depth of field" doesn't have to mean as you
assume it could.

[A complimentary Cc of this posting was sent to
frederick
], who wrote in article 1161030861.1650@ftpsrv1:
Anyone knows that switching formats does not bring any change in DoF -
if one WANTS to produce identical images, one can.

Only when maximum DOF is the objective. Not when shallow DOF is sought.

When true, this is a part of what I said: one needs the same "lens
quality at the used f-stop". When/If you can open 35mm-formfactor
lens to the same entry pupil as the LF lens (with the same "optical
build quality"), they create identical images (only scaled
differently) - same diffraction, "same" abberations, same DoF. Of
course, this "If/when" is rarely possible...

Different formats produce non-identical results only because of
different "effective MP count", and lens quality at the used f-stop
(well, QE may also enter the picture, e.g., when you compare film to
digital). You just use f-stop "proportional" to the formfactor, and
everything else comes out to be identical.

You have quoted selectively:
"The only downside to my new system is working with depth of field. On
my 4x5 Linhof, I have a focusing gauge that allows me to quickly
determine the optimum f stop for each situation. With the Mamiya and the
zoom lenses, this is much harder to determine. On the plus side, a
composition that required a 200mm on the 4x5 needs only an 80mm for the
P45 sensor. And with that smaller focal length is around a 2.5 times
increase in available depth of field."

That comment "available depth of field" doesn't have to mean as you
assume it could.

I do not agree with you. Read: "on the plus side"; obviously, he
thinks that with smaller formfactor he will have larger depth of
field. (This is only true if he would use the same f-stop; but when
you convert to a more open f-stop needed to get the same diffraction
[measured in the subject space, i.e., in angular units], one gets
exactly the same DoF...)

Yours,
Ilya

Ilya Zakharevich wrote:
[A complimentary Cc of this posting was sent to
frederick
], who wrote in article 1161030861.1650@ftpsrv1:
Anyone knows that switching formats does not bring any change in DoF -
if one WANTS to produce identical images, one can.

Only when maximum DOF is the objective. Not when shallow DOF is sought.

When true, this is a part of what I said: one needs the same "lens
quality at the used f-stop". When/If you can open 35mm-formfactor
lens to the same entry pupil as the LF lens (with the same "optical
build quality"), they create identical images (only scaled
differently) - same diffraction, "same" abberations, same DoF. Of
course, this "If/when" is rarely possible...

Different formats produce non-identical results only because of
different "effective MP count", and lens quality at the used f-stop
(well, QE may also enter the picture, e.g., when you compare film to
digital). You just use f-stop "proportional" to the formfactor, and
everything else comes out to be identical.

You have quoted selectively:
"The only downside to my new system is working with depth of field. On
my 4x5 Linhof, I have a focusing gauge that allows me to quickly
determine the optimum f stop for each situation. With the Mamiya and the
zoom lenses, this is much harder to determine. On the plus side, a
composition that required a 200mm on the 4x5 needs only an 80mm for the
P45 sensor. And with that smaller focal length is around a 2.5 times
increase in available depth of field."

That comment "available depth of field" doesn't have to mean as you
assume it could.

I do not agree with you. Read: "on the plus side"; obviously, he
thinks that with smaller formfactor he will have larger depth of
field. (This is only true if he would use the same f-stop; but when
you convert to a more open f-stop needed to get the same diffraction
[measured in the subject space, i.e., in angular units], one gets
exactly the same DoF...)

Yours,
Ilya
Yes - but he also gets increased DOF at the same f-stop , same FOV, and
same shutter speed. For sure a big drawback for large format is slow
shutter speeds, as although you can use a tripod, you can't stop things
from moving in the frame.
Ultimately you are of course correct - but it may mean that you can't
take a photo with even a moving snail in the frame ;-)