How does choice of developer affect film speed?
blut...@gpcom.net
could "give true film speed increase," and wonder what is meant by
this. What particularly confuses me is that the same photographers
shoot the film at the factory recommended ISO, so where does the speed
gain come into play?
Thank you for your time.
Gregory Blank
detail in a given area. The amount of light needed to produce
a specific density value is thus lessened.
In article <1107009524.1...@f14g2000cwb.googlegroups.com>,
blut...@gpcom.net wrote:
--
LF Website @ http://members.verizon.net/~gregoryblank
"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
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Alan Smithee
You have to think in terms of what it is that "speed" describes and why it's
useful with regards to photography, it's not just a number on the camera
dial (ok it is to some). Speed or the film's "rating" describes how the
manufacturer predicts the emulsion will react when struck by light and then
developed with a certain developer and the results then graphed
scientifically on an exposure scale (the H&D curve). All developers are not
created equal. You wouldn't except the same results processing two
identically exposed frames if one was developed in D-76 and the other in
coffee developer(Cafenol?) or horse piss for that matter. A developer can be
mixed at different strengths too, a strong developer is described as
"aggressive" a mild developer as "soft" or "gentle" think of this in
woodworking terms. If you used a coarse rasp to round off a corner you'd get
the job done quick but the wood would be rough, if you used 180 grit sand
paper to round off the corner it might take a while longer and the corner
would be smoother, which you choose depends on how much time you have and
what is acceptable in the finished product -- both are correct in their own
context. It's often advantageous to be able to shoot a subject with a faster
shutter speed, smaller aperture or longer lens. Carrying a tripod around
allows you to do quite a bit but isn't always practical. If you can bumped
up the shutter speed by declaring "this film is faster than that film" or
"this developer rates my film 1 or 2 stops faster" then you extend the range
of what you're able to do with the camera.
For example, if I shoot the same scene, let's say a grey card, and develop
a frame of TMAX 400 in developer "A" then measure (with a densitometer) how
dark (or dense) the image of card is on the negative and I get a value of
0.95 Then develop the same scene in developer "B" and the grey card measures
1.25 in density it means (or might mean) developer "B" is capable of
creating 1 stop more density on the negative than developer "A" because a
0.30 increment on the "photo density" scale (H&D curve) equals 1 stop. To
some degree "density" equates to data or usable "information" on the film so
a better developer means you have more negative to work with better detail
in the shadows might be one such benefit.
Chris
Looks like lots of testing in store for me. ;-)
dan.c...@att.net
How does choice of developer affect PAPER speed?
I've noticed that paper exposure varies with paper
developer.
I've a hunch that variance can be used to test
film developers using paper. Doing that would be a
lot quicker than shooting a roll of film for
each developer test. Dan
Gregory Blank
dan.c...@att.net wrote:
Well some developers and various dilutions produce more or less
contrast, contrast is relative to speed of the paper for a given
exposure and the other "same criteria".
The chemical make up of the emulsions between film and paper
I think are too dissimilar for that purpose.
Richard Knoppow
for measuring film speed which specifies the conditions of exposure and
development of the film. There was once a standard developer (actually
two) but the standard no longer requires these to be used. Any
developer can be used provided the developer is stated with the speed.
The standard is supposed to give a number that when set into the
computer of an exposure meter will give an exposure resuting in good
tonal rendition. The problem comes when the conditions of actual use
are not similar to those assumed by the standard.
One of the variables is the developer.
The standard specifies a range of exposure for the test and a range
of densities to be generated on the film. In effect, it specifies a
contrast index but it is indirect. If the film is developed to a
different contrast the effective speed will be different than given by
the standard.
Developers vary in their ability to select low values of latent
image. The range is not very large. D-76 is considered a standard for
"full" film speed for comparison to other developers. D-76 is not quite
optimum for maximising speed although close. Some Phenidone developers
are closer to being optimum, they give an increase in speed, that is, a
lower exposure will result in a given density on the film at the same
degree of development which is another way of saying contrast. So, when
one of these developers is used for the ISO test it will result in a
higher speed than if D-76 was used. Developers like Microphen, Xtol,
T-Max RS, fall into this class. Some developers destroy some of the
latent image or are not able to differentiate it from unexposed silver
halide crystals. These developers give a lower density for the same
value of exposure and development. Extra fine grain developers, like
Microdol-X or Ilford Perceptol, when used full strength, fall into this
class. A few developers fall in between somewhere.
The overall range of speed in comparison to D-76 is about plus or
minus 3/4 stop, not a lot.
Since the ISO standard effectively specifies a contrast index
develolping to a different contrast will affect the speed. The contrast
index of the standard is fairly high, suitable for diffusion printing.
If film is developed to a lower contrast, say for use in a condenser
enlarger, the speed will become less. In this case by about 3/4 stop.
The ISO speed is based on the idea that one should give film the
minimum exposure possible and still get good tonal rendition. The
reason is that grain and loss of sharpness increase with density. So,
there is a benefit in making negatives on the thin side, provided the
tonal rendition is good. Increasing exosure will sometimes result in
better tonal rendition with little increase in grain or loss of
sharpness especially with modern films which have thin, fine grain,
emulsions.
Because the ISO speed is designed to give minimum exposure, and
because it has little safety factor, film does not have much
underexposure latitude (room for exposure error) but usually has
enormous overexposure latitude.
Richard Knoppow
Los Angeles, CA, USA
dick...@ix.netcom.com
Jean-David Beyer
> How does choice of developer affect PAPER speed?
> I've noticed that paper exposure varies with paper
> developer.
> I've a hunch that variance can be used to test
> film developers using paper. Doing that would be a
> lot quicker than shooting a roll of film for
> each developer test. Dan
>
The choice of paper developer does affect PAPER speed. I have not
specifically tested this, but I note that straight Amidol (Ansco 113)
developer requires about double the paper exposure than does D:72 1+2.
I think testing film developers using paper is a silly idea: the
conditions are completely different and the time and materials required to
ascertain the relationship for each and every combination of
film-developer-paper would surely exceed the effort and expense of testing
the film directly. Why make things more complicated than they need to be?
--
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ArtKramr
>From: Jean-David Beyer jdb...@exit109.com
>I have not
>specifically tested this, but I note that straight Amidol (Ansco 113)
>developer requires about double the paper exposure than does D:72 1+2.
>
>I think testing film developers using paper is a silly idea: the
Amidol is a paper developer.
Arthur Kramer
344th BG 494th BS
England, France, Belgium, Holland, Germany
Visit my WW II B-26 website at:
http://www.coastcomp.com/artkramer
uraniumc...@yahoo.com
Certain developers give more or less speed, almost always balancing
other desirable qualities. This has been known for decades. It depends
on the formulation. The ISO speed is measured using a specified
developer, which is similar to D-76.
uraniumc...@yahoo.com
Arthur Kramer
344th BG 494th BS
England, France, Belgium, Holland, Germany
Visit my WW II B-26 website at:
http://www.coastcomp.com/artkramer "
Amidol is also a film developer. Depends on how you mix it and use it.
Jean-David Beyer
>>Subject: Re: How does choice of developer affect film speed?
>>From: Jean-David Beyer jdb...@exit109.com
>
>
>>I have not
>>specifically tested this, but I note that straight Amidol (Ansco 113)
>>developer requires about double the paper exposure than does D:72 1+2.
>>
>>I think testing film developers using paper is a silly idea: the
>
>
> Amidol is a paper developer.
Sure: that is what I said.
I know you can develop film with it (since you can develop almost anything
in almost anything if you calibrate right, and put enough restrainer in
when printing on paper). Ansco 113 was definately meant for paper.
>
>
> Arthur Kramer
> 344th BG 494th BS
> England, France, Belgium, Holland, Germany
> Visit my WW II B-26 website at:
> http://www.coastcomp.com/artkramer
>
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Agit Prop
uraniumc...@yahoo.com wrote:
You answer the question by rearranging it into a statement. Brilliant.
Q: "Why is the sky blue?"
A: "Because the sky is blue."
Duh.......
no-name
completion") in some hypothetical perfect developer, it will by definition
have produced as much image density as possible, and more development time
will not increase density. It will only increase fog.
For most of the films ordinarily used by people like us, that takes
somewhere in the range of 15 to 30 minutes of development, in a developer
considerably more dilute than normal. In a sense, a film's true inherent
speed is a function of how much (or little) exposure it takes to create a
target gamma on development to completion.
Reasonably short development time has long been a goal when compounding
pictorial developers -- not too short, because that affects repeatability,
and not too long, because we get impatient. So most developers in common use
are compounded to work for something like five to twelve minutes, usually
seven to ten or so, to give a fully developed image at pictorial gamma.
However, this shorter time must be paid for, and the price is that you need
more exposure to get that fully developed image. In other words, you must
rate the film at something lower than its true speed.
So the issue is not really how or why certain developers increase film
speed. They don't. They just decrease it less than others.
The effect is spectacularly evident with narrow-latitude films like
microfilms, which I have experimented with quite a lot. A microfilm that
must be rated at 4 or 6 when developed in pyro for six minutes can be rated
at 80 or 100 when developed in phenidone for 15-20 minutes. Pyro and
phenidone are very different chemicals, and they react during development at
different rates, and with different kinetics, which is why they yield such
markedly different image qualities. In practical terms, phenidone "attacks"
more quickly and has less tendency to develop unexposed grains (fog). Pyro
is the oppsite. So you can leave the film in phenidone longer, and come
closer to achieving the film's true inherent speed
Most film speeds are deduced using a Metol-borax developer (similar to D76),
which produces reasonable development times but does not maximize speed.
Most developers that are considered to increase film speed are compounded
with phenidone, and if I remember correctly, most must be used at somewhat
longer development times.
David Foy
_________________________
http://www.bluefire.ca
<uraniumc...@yahoo.com> wrote in message
news:1107537464.7...@o13g2000cwo.googlegroups.com...
Nicholas O. Lindan
> "Greetings. I have read many posts
You mean advertisements, I hope.
> stating that a particular developer could "give true film
> speed increase," and wonder what is meant by this.
"Make money fast", "Buy Herbal Viagra", "Hot housewife wants to
come to your place now!" ....
It is a lie. Developers do not affect film speed. The
manufacturer is telling you to over-develop your film.
This can be done with just about any developer, some better than
others but nothing spectacular. The effect is to increase
negative contrast on underexposed film -- it is this
underexposure that is touted as a 'speed increase'.
"no-name" <nos...@thisaddress.please> wrote
> If a given film is exposed to a step wedge and developed fully ("to
> completion")
I don't think film is ever normally developed to completion. I have
done it with a scrap of film: let it sit in Dektol for an hour with the
lights on. The stuff got to 4.2 OD! I didn't check fog level.
If development times are increased all that happens
is contrast goes through the roof: fog or 4.2 OD.
We develop paper to completion, so I find the question of "why not
film?" interesting. 1:1000 Rodinal _will_ stop working after a
while but it isn't because the film is done to completion.
--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/
no-name
"Nicholas O. Lindan" <s...@sig.com> wrote in message
news:rt6Td.9605$x53...@newsread3.news.atl.earthlink.net...
> .... Developers do not affect film speed.
There is probably some technical sense in which you are right. The issue
being discussed arises from what many photographers observe in practice. For
example, Fuji Super HR microfilm must be exposed at EI 4 to 6 if you want
the best possible negatives from pyro
(http://kcbx.net/~mhd/2photo/film/choice/superhr), but can be exposed at EI
25 to 100 if you want the best possible negatives from POTA, Technidol, or
H&W Control. I cite microfilms because they provide an extreme example, but
it happens with pictorial black and white films too on a less flagrant
scale. Have you not noticed it in your own work?
> "no-name" <nos...@thisaddress.please> wrote
> > If a given film is exposed to a step wedge and developed fully ("to
> > completion")
>
> I don't think film is ever normally developed to completion. I have
> done it with a scrap of film: let it sit in Dektol for an hour with the
> lights on. The stuff got to 4.2 OD! I didn't check fog level.
>
Forgive me if I've mis-used the term "to completion." I am describing a real
and observable phenomenon. If you experiment with a sensitometer and a
21-step wedge, you will see what I'm describing. You get to a point where
you've got the best tone scale you're going to get, and after that, all that
happens is fog (and, as you point out, rising gamma, which I neglected to
mention).
A step wedge is an abstraction of a scene that contains a near-infinite
range of tones from solid black to solid white, which is what most of us
photograph, most of the time.
If the real point of your post is that film speeds and developer properties
are sometimes, or even often, improperly advertised, I have to say I'm not
sure.
I test a lot of film, and a few developers, and while a few film
manufacturers are inconsistent in their development time recommendations,
most are consistent and accurate. I test in the lab, with a sensitometer,
and in the field, with 1/3 stop bracketing. I find virtually all of the film
manufacturers rate their films accurately for development in D76. Certainly
close enough to be within the limits of experimental error.
Claims that some developer "increases film speed" are usually made by
enthusiasts, not by manufacturers. Certainly the developers I have tested
have not been misrepresented. I hasten to add there are several chemistry
manufacturers whose products I am not familiar with.
David Foy
--
Bluefire Laboratories
http://www.bluefire.ca
Nicholas O. Lindan
Point taken. However, my experience with Delagi, Technidol and
POTA is that they produce the same contrast if I expose at the same ASA
and adjust the development time for the same step-wedge response.
For me, Tech Pan works best at ASA 7, though I shoot it at 25 for
snap shots when I am willing to sacrifice the shadow detail. For me
it is rich shadow detail with unblocked highlights that makes it.
> it happens with pictorial black and white films too on a less flagrant
> scale. Have you not noticed it in your own work?
Frankly, no. I don't push anymore, I get better results at normal
development and living with the resulting low-contrast negatives with
either high-contrast paper or scanning. If shadows are blank in the unpushed
negative they
are equally blank in the pushed one.I find pushing just slaughters
any highlight detail: the combination of no shadow detail _and_ no
highlight detail makes for horrid photographs. I can live with one or
the other, not both.
My view on 'high-speed' developers is that the difference is in the
instructions: the HS developers tell you to push as a matter of course,
they declare this to be 'normal development' when it isn't. I found
these developers work better at shorter developing times and normal exposure.
This is all from Tri-X experience of many years ago. I haven't revisited
the subject: I just continue to take pictures with whatever light there
is, process normally and do the best I can with the resulting negatives.
The result of not pushing looks very natural: the camera doesn't see well
in low light and neither does the eye, it _looks_ like it was taken by
candlelight because it was.
> > > If a given film is exposed to a step wedge and developed fully ("to
> > > completion")
> >
> > I don't think film is ever normally developed to completion. I have
> > done it with a scrap of film: let it sit in Dektol for an hour with the
> > lights on. The stuff got to 4.2 OD! I didn't check fog level.
>
> Forgive me if I've miss-used the term "to completion." I am describing a real
> and observable phenomenon. If you experiment with a sensitometer and a
> 21-step wedge, you will see what I'm describing. You get to a point where
> you've got the best tone scale you're going to get, and after that, all that
> happens is fog (and, as you point out, rising gamma, which I neglected to
> mention).
I think we are saying the same thing. 'Completion' to me means that densities
are as high as they are ever going to get - you can't develop any more, there
is no 'after that'. This is somewhat what happens with developing paper: after
two minutes in the developer there isn't much change in the image and another
two minutes doesn't make a whole lot of difference. Doubling normal film
development time makes a heck of a difference.
> If the real point of your post is that film speeds and developer properties
> are sometimes, or even often, improperly advertised, I have to say I'm not
> sure.
What I am saying is:
o Pushing with ordinary developers never makes things better. Pushing is
different from modifying contrast by over/under exposure/development.
o There is a group of fringe commercial developers that make false claims for
being able to increase film speed: Accufine, Diafine, Edwal ...
> I test a lot of film, and a few developers, and while a few film
> manufacturers are inconsistent in their development time recommendations,
> most are consistent and accurate.
Agreed. Kodak, Ilford, Agfa etc. make no misleading claims.
> I hasten to add there are several chemistry
> manufacturers whose products I am not familiar with.
You are not missing much.
UC
It's not tautology. I said 'balancing other properties'. That means
more speed, more grain, less sharpness, more fog.
UC
Nicholas O. Lindan wrote:
> <uraniumc...@yahoo.com> wrote in message
> > "Greetings. I have read many posts
>
> You mean advertisements, I hope.
>
> > stating that a particular developer could "give true film
> > speed increase," and wonder what is meant by this.
>
> "Make money fast", "Buy Herbal Viagra", "Hot housewife wants to
> come to your place now!" ....
>
> It is a lie. Developers do not affect film speed.
Yes, they do. Some give less speed and some give more. Rodinal gives
less speed than D-76, and more grain and sharpness. Microdol-X gives
less speed than D-76, with finer grain and less shrpness.