Improved T-Max 400

"Richard Knoppow" wrote in message
...

[...] The problem is that unless one is shooting sheet film one is
required to sacrifice most of two rolls of fairly expensive film in order
to shoot the subject at nearly the same time in the same camera. I

Life is short, Richard. What's two rolls in a lifetime if it settles the
question?

On Oct 31, 1:10 am, "Richard Knoppow" wrote:
"UC" wrote in message

ups.com...



On Oct 29, 10:35 pm, "Richard Knoppow"
wrote:

Richard:

It is easy to see the differences in shadow and highlight
contrast in
Tri-X vs TMY, when developed for similar overall contrast,
in
negatives taken in the same illumination at the same time
of the same
subject matter . In Tri-X Pan, the shadows have more
contrast and the
highlights have less. If you would take the trouble to do
this sort of
test you will see it quite clearly.

Well, I have used both films but haven't actually
exposed a roll of each to the same targets in the same
camera. I also have some favorite test subjects including a
row of houses across the street. I probably have a hundred
pictures of these from my front yard. I will have to get a
fresh roll of the two films and try this. My usual developer
is D-76 diluted 1:1. This is included in the charts for both
films and should work well with them. I don't know when I
will be able to get to this, I guess I will just have to
make the time. The problem is that unless one is shooting
sheet film one is required to sacrifice most of two rolls of
fairly expensive film in order to shoot the subject at
nearly the same time in the same camera. I guess I could
bracket and use up more film plus compare the tone rendition
for several exposures.

--
---
Richard Knoppow
Los Angeles, CA, USA


Well, that's what I have done. I have shot several rolls of each film,
adjusting developing times to give similar overall contrast with each
film. It's expensive and time-consuming, but teh developing times
given by manufacturers are often excessive and inconsistent.

On Oct 31, 8:05 am, "pico" pico.pico.net wrote:
"UC" wrote in message

ups.com...

Here is the curve for TMY:

http://www.kodak.com/global/en/profe...hPubs/f4016/f0...

Here is the curve for Tri-X Pan:

http://www.kodak.com/global/en/profe...hPubs/f4017/f0...

Do you see the difference?

What part of that line/curve is actually useful for making photographs? You
never use the so-called shoulder - it is outside the useful exposure range.

When you use the film, the differences appear. I develop much less
than the longest time shown. The point is that you CAN easily see the
differences. Kodak brought out Polymax paper specifically to combat
the problem. Now that Kodak is out of the paper business, they may
have adjusted the curve of TMY to work better with other papers. After
all, Tri-X Pan does sell better. TMY is 20 years old!

Richard Knoppow wrote:
For peter, the 0.8 factor is NOT the same as 1, it is 20%
different which is quite different. The density value I
stated is the value from the charts in the standard for the
log exposure at the speed point multiplied by the reciprocal
of 0.8, that is 1.25 and should be the log exposure at the
point on the toe approximating the Jones minimum gradient
point. The 0.8 factor is in the standard and it used to
calculate the speed.


I think this is getting a little confusing for me.
I will state what I understand as clearly as possible,
and you can tell me if I'm going wrong somewhere.


Kodak Speed
-----------
In 1939 Kodak introduced a new speed system based
on the results of extensive psychophysical research.
This research showed that the minimum useful exposure
Required to yield an 'excellent' print was at a point
where the gradient of the H&D curve was 0.3x times the
average gradient of the slope over a range from the
exposure point to log 1.5 above the exposure point.

Finding this point called the "Jones Point" requires
a recursive operation. One has to first guess the point
to find the average gradient, and then refine your guess
on the second try.

Kodak speed is given by the formula:

Kodak Speed = 1/E

Where E is the Jones Point in Metre-Candle-Seconds.
(Same as Lux Seconds).

If you had such a thing as a exposure meter
calibrated for Kodak speeds, there would
be no safety factor. Kodak Speed didn't catch
on because few if any people owned such meters.


OLD ASA Speed 1943
------------------

In 1943 the ASA adopted the Kodak speed system
with one important change.

The formula was now

ASA Speed = 1/(4 x E)

This was intended to give numbers usable with
both Weston and GE meters. The new ASA standard
meters were to be calibrated midway between the
old Weston and GE calibrations. With an ASA
meter, old ASA speed had a safety factor of
2.5 (1 1/3 stops).

I don't think there was a particular level
of negative contrast required by the old ASA
standard, because the Jones point remains in the
same place over a fairly wide range of development
contrasts. Development contrast is supposed
to be typical of photofinishing practice.

DIN Speed
---------
The original DIN speed system (1936) was
very unsatisfactory. Sometimes it would
even get the relative speeds of films
in the wrong order. The reason for this
was that the original DIN standard required
films to be developed for maximum speed
rather than according to normal use.
Old DIN speeds are indicated by the presence
of "/10" so 24/10 degrees DIN is an old
DIN speed.

In the 1957 DIN standard, the "optimal
development" was replaced by a rigidly
specified development more typical of
real practice. People soon noticed that
the new DIN numbers actually made sense.

New ASA Speed
-------------
Since the new DIN system was easier for
film manufacturers in practice and
actually worked pretty well, the ASA
decided to adopt a new system based on
DIN speeds. It was also decided to
abandon the rather large safety factor
and have speeds roughly twice that of
the old while keeping meter calibration
unchanged.

The 2:1 relationship is typical, but is
not exactly true of all films as the following
table shows.

Film OLD ASA NEW ASA
---- ------- -------
Plus-X 35mm 80 125
Verichrome Pan 80 125
Tri-X Pan Sheet 200 320
Tri-X Pan 35mm 200 400

ISO Speed
---------
The current ISO standards for B&W film
are essentially the same as the New DIN
and New ASA standards.

Where Hm = the 0.1 above base + fog point in lux seconds.

Arithmetic speed S = 0.8/Hm

Log speed S degrees = 1 + 10 x log10 0.8/Hm

The Log ISO is in fact the same as the
DIN speed.

DIN Speed = 10 log10 1/Hm

Because 10 log10 0.8 = -1
(at least very very nearly).

So Log ISO and DIN are both equal to
the log exposure of the 0.1 above base + fog point
divided by minus 10.

The 0.8 denominator in the arithmetic speed
makes 1 ASA equal to 1 DIN and places the
New ASA or ISO arithmetic speed where it
was wanted.

example:
Tri-X pan 400
ISO 400/27 degrees
New ASA 400
New DIN 27
OLD ASA probably still 200

0.1 above base fog point (Hm) is -2.7 log lux seconds

This is true from all formulas.

ISO Artith or New ASA = 0.8/Hm
= 0.8/10^-2.7
= 0.8/0.002
= 400

ISO Log Degrees = 1 + 10 x log10 0.8/Hm
= 1 + 10 x log10 0.8/10^-2.7
= 1 + 10 x log10 400
= 1 + 10 x 2.6
= 1 + 26
= 27

DIN Speed = 10 x log10 1/Hm
= 10 x log10 1/10^-2.7
= 10 x log10 501
= 10 x 2.7
= 27
Same Answer!

DIN Speed of 27 means Hm is -2.7 log lux seconds.
- neat - all you have to do is divide by negative 10.

If Old ASA 200 then Jones point E = - 2.9 log lux seconds

ASA Speed = 1/(4 x E)
= 1/(4 x 10^-2.9)
= 1/(4 x 0.00126)
= 1/0.00504
= 198.41

Close enough.

Peter.
--

On Oct 31, 5:38 pm, Peter Irwin wrote:
Richard Knoppow wrote:
For peter, the 0.8 factor is NOT the same as 1, it is 20%
different which is quite different. The density value I
stated is the value from the charts in the standard for the
log exposure at the speed point multiplied by the reciprocal
of 0.8, that is 1.25 and should be the log exposure at the
point on the toe approximating the Jones minimum gradient
point. The 0.8 factor is in the standard and it used to
calculate the speed.

I think this is getting a little confusing for me.
I will state what I understand as clearly as possible,
and you can tell me if I'm going wrong somewhere.

Kodak Speed
-----------
In 1939 Kodak introduced a new speed system based
on the results of extensive psychophysical research.
This research showed that the minimum useful exposure
Required to yield an 'excellent' print was at a point
where the gradient of the H&D curve was 0.3x times the
average gradient of the slope over a range from the
exposure point to log 1.5 above the exposure point.

Finding this point called the "Jones Point" requires
a recursive operation. One has to first guess the point
to find the average gradient, and then refine your guess
on the second try.

Kodak speed is given by the formula:

Kodak Speed = 1/E

Where E is the Jones Point in Metre-Candle-Seconds.
(Same as Lux Seconds).

If you had such a thing as a exposure meter
calibrated for Kodak speeds, there would
be no safety factor. Kodak Speed didn't catch
on because few if any people owned such meters.

OLD ASA Speed 1943
------------------

In 1943 the ASA adopted the Kodak speed system
with one important change.

The formula was now

ASA Speed = 1/(4 x E)

This was intended to give numbers usable with
both Weston and GE meters. The new ASA standard
meters were to be calibrated midway between the
old Weston and GE calibrations. With an ASA
meter, old ASA speed had a safety factor of
2.5 (1 1/3 stops).

I don't think there was a particular level
of negative contrast required by the old ASA
standard, because the Jones point remains in the
same place over a fairly wide range of development
contrasts. Development contrast is supposed
to be typical of photofinishing practice.

DIN Speed
---------
The original DIN speed system (1936) was
very unsatisfactory. Sometimes it would
even get the relative speeds of films
in the wrong order. The reason for this
was that the original DIN standard required
films to be developed for maximum speed
rather than according to normal use.
Old DIN speeds are indicated by the presence
of "/10" so 24/10 degrees DIN is an old
DIN speed.

In the 1957 DIN standard, the "optimal
development" was replaced by a rigidly
specified development more typical of
real practice. People soon noticed that
the new DIN numbers actually made sense.

New ASA Speed
-------------
Since the new DIN system was easier for
film manufacturers in practice and
actually worked pretty well, the ASA
decided to adopt a new system based on
DIN speeds. It was also decided to
abandon the rather large safety factor
and have speeds roughly twice that of
the old while keeping meter calibration
unchanged.

The 2:1 relationship is typical, but is
not exactly true of all films as the following
table shows.

Film OLD ASA NEW ASA
---- ------- -------
Plus-X 35mm 80 125
Verichrome Pan 80 125
Tri-X Pan Sheet 200 320
Tri-X Pan 35mm 200 400

ISO Speed
---------
The current ISO standards for B&W film
are essentially the same as the New DIN
and New ASA standards.

Where Hm = the 0.1 above base + fog point in lux seconds.

Arithmetic speed S = 0.8/Hm

Log speed S degrees = 1 + 10 x log10 0.8/Hm

The Log ISO is in fact the same as the
DIN speed.

DIN Speed = 10 log10 1/Hm

Because 10 log10 0.8 = -1
(at least very very nearly).

So Log ISO and DIN are both equal to
the log exposure of the 0.1 above base + fog point
divided by minus 10.

The 0.8 denominator in the arithmetic speed
makes 1 ASA equal to 1 DIN and places the
New ASA or ISO arithmetic speed where it
was wanted.

example:
Tri-X pan 400
ISO 400/27 degrees
New ASA 400
New DIN 27
OLD ASA probably still 200

0.1 above base fog point (Hm) is -2.7 log lux seconds

This is true from all formulas.

ISO Artith or New ASA = 0.8/Hm
= 0.8/10^-2.7
= 0.8/0.002
= 400

ISO Log Degrees = 1 + 10 x log10 0.8/Hm
= 1 + 10 x log10 0.8/10^-2.7
= 1 + 10 x log10 400
= 1 + 10 x 2.6
= 1 + 26
= 27

DIN Speed = 10 x log10 1/Hm
= 10 x log10 1/10^-2.7
= 10 x log10 501
= 10 x 2.7
= 27
Same Answer!

DIN Speed of 27 means Hm is -2.7 log lux seconds.
- neat - all you have to do is divide by negative 10.

If Old ASA 200 then Jones point E = - 2.9 log lux seconds

ASA Speed = 1/(4 x E)
= 1/(4 x 10^-2.9)
= 1/(4 x 0.00126)
= 1/0.00504
= 198.41

Close enough.

Peter.
--


It is my opinion, and that of many others, that the 'new' ASA speed
sytem introduced in 1959 gives numbers that are too high, by about 2/3
stop.

UC wrote:

It is my opinion, and that of many others, that the 'new' ASA speed
sytem introduced in 1959 gives numbers that are too high, by about 2/3
stop.

I think the primary reason for this is that the question
you want the ISO rating to answer is a different question
from the one it was designed to answer.

The question the speed rating is designed to answer
is "what is the minimum exposure required to produce
a negative from which a print judged to be 'excellent'
can be made?"

The question you probably want answered may be
something like "What exposure meter setting will
consistently give negatives that are easy to print
well?"

The answer to the second question is going to generally
be a lower exposure index than the ISO standard.

Peter.
--

"UC" wrote in message
ps.com...
On Oct 31, 8:05 am, "pico" pico.pico.net wrote:
"UC" wrote in message

What part of that line/curve is actually useful for making photographs?
You
never use the so-called shoulder - it is outside the useful exposure
range.

When you use the film, the differences appear. I develop much less
than the longest time shown. The point is that you CAN easily see the
differences. Kodak brought out Polymax paper specifically to combat
the problem. Now that Kodak is out of the paper business, they may
have adjusted the curve of TMY to work better with other papers. After
all, Tri-X Pan does sell better. TMY is 20 years old!

I use the film. And are you not aware that Tri-X has changed again?

"Peter Irwin" wrote in message
...
UC wrote:

It is my opinion, and that of many others, that the 'new' ASA speed
sytem introduced in 1959 gives numbers that are too high, by about 2/3
stop.

I think the primary reason for this is that the question
you want the ISO rating to answer is a different question
from the one it was designed to answer.

The question the speed rating is designed to answer
is "what is the minimum exposure required to produce
a negative from which a print judged to be 'excellent'
can be made?"

The question you probably want answered may be
something like "What exposure meter setting will
consistently give negatives that are easy to print
well?"

The answer to the second question is going to generally
be a lower exposure index than the ISO standard.

MOST EXCELLENT observation. Kodak set the metrics. Those are the same folks
who conducted a hugely expensive and detailed survey of average customers
(largely of automatic processing) and Kodak set their metrics to those
standards, as abysymal and utterly tasteless as they were, they still
represented the drug-store processing majority. (Imagine the Bell curve -
who wants to live on top?) Oh, and what camera did Kodak come out with in
response to that study? The wholly embarassing failure, the Disc Camera!

But to add a contemporary data point - with so many people scanning
negatives, a whole new scale must be developed (no pun). Me, I'm still
scanning prints. So shoot me already.

pico pico.pico.net wrote:


MOST EXCELLENT observation. Kodak set the metrics. Those are the same folks
who conducted a hugely expensive and detailed survey of average customers
(largely of automatic processing) and Kodak set their metrics to those
standards, as abysymal and utterly tasteless as they were, they still
represented the drug-store processing majority.

Thanks, but I think you misunderstand me. I didn't mean
anything sarcastic when I used "excellent" in quotes.

I just meant that the two questions:

"What is the highest EI setting I can use and still
get excellent quality prints?"

and

"What is the best all-round EI setting to use in practice?"

are different questions with different answers.
The ISO speeds for negative film provide good answers
to the first question, but not necessarily to the second.

The important detail to remember is that the ISO speeds
are intended to get you very near the minimum exposure
that will work well with negative film. The maximum
exposure is generally much higher.

The optimum setting for your purposes is something
you have to find for yourself. All film manufacturers
including Kodak actually say this.

Peter.
--

"Peter Irwin" wrote in message
...

The important detail to remember is that the ISO speeds
are intended to get you very near the minimum exposure
that will work well with negative film. The maximum
The optimum setting for your purposes is something
you have to find for yourself. All film manufacturers
including Kodak actually say this.

Of course. So shoot short rolls or sheet film and custom expose and develop.