Rand chooses to argue thusly:
. I have ALL the testing I need. If you want to argue with the test
results of the copal test I posted you are welcome to email him.
dont care to when i can test as many as I like here, and I've tested more
than enough.
Second over exposing doesn't make grain less it makes it more and tighter
which LOOK like less grain when its MORE.
that is what people refer to as 'grain'. they are not talking about the
grain, but the holes between the grain. we all know this. Raising it like
it's a grand revelation avoids agreeing that denser colours, denser tones
look less grainy.. or more filled out (as the dyes run together and leave
less gaps)
I think they call this physics.
I would put money on Jack Karpens tri-x 400 shot at 400 being better
I don't put my money on anyone's name. names are irerelevant to a
scientist.. only the facts have meaning and they should stand without names
being dropped like confetti
then anything shot at 200. I mean this is meticulous care. I know lots
of people that shoot tmax 400 at 200 but then it also comes down to how
its
being process and what juice and water minerals and on and on and on.
soup it the same, dear god - changing the development mostly affects
contrast and has nothing to do with speed.
Jack Karpen - School of Photographic Arts and Sciences at RIT
Reference: U.S. Navy manual of photography, vol. 1 & 2, 1947 edition.
It should be noted that photographic emulsion consists of silver
suspended in gelatin.
This is very similar to those holiday jello molds (so popular this time of
year) where odd bits of various fruits are suspended in colored (usually
green) and flavored gelatin.
I read this years back and laughed as loudly then as I did now. Did you
know people also eat gelatin? did you also know the justification is that
it's rich in protein? Common knowledge says protein is good for us, and
thus it is advocated as a food source for many elderly and infirm. Whant to
see how right that is? Gelatin is inedible to us - sure it's protein, but
so is melamine. Good for cows, not for humans - we cannot digest it. it
has contributed to much malnutrition and quite a few deaths, yet it is
still sold as a food! myths abound in thsi world and they're very hard to
kill, especially when the inexperienced cite experts and perpetuate the
mis-truths.
it is suspended in a flexible solid, call it a plastic, call it an emulsion.
no, nothing is moving in this suspension when it's dry and if you've ever
worked with biological suspensions in gelatin you'll know not much migrates
even when it's wet!
The similarity continues in that we know what occurs when the jello mold
is
dropped or treated in a rough manner. The bits of fruit are displaced to a
greater or lesser degree. This same phenomena can be witnessed when
viewing
student work. When viewing fuzzy pictures be sure to question students on
how the film was handled before processing
I'd bet the fuzzy pics were more likely a result of poor aperture selection
on the enlarger, or not allowing for the slight expansion and deformation of
the neg when enlarging. David Vestal wrote extensively on this. It seems
few bothered to heed his advice.
If he caught us hold our stainless or aluminum film processing tanks in
our
hands it was not good for you grade. I would say I learned much from
jack
on the nature of what is the right way to process film to then apply that
towards the rest of my education.
awesome.
This still has ZERO to do with the ISO not being listed as correct.
agreed.
Because they thought the resulting dies in the film where crap but looked
nice at different settings is a non point. Its an aesthetic choice not a
as designed to operate based on whatever it was they where shooting for.
They're German's the looked up some math and then did that exactly based
on what works in a LAB and over exposing it doesn't make the ISO WRONG its
makes it an aesthetic choice in how to use that film.
a stated ISO mean something in most parts of the world, it means it complies
with international standards.
In this case it did not. This film was written up with rave reviews
across the world for the richness of the colours and depth in the dark
tones. However, the film speed - again Ilford Standard, was stated
incorrectly. basic stuff. a whole bunch of students would demonstrate this
each semester and shrug and go .. 'huh!' This college was (..was, ain't no
more) internationally recognised as one of the three top places in the world
for photography, specifically science photography - the place where Kodak
staff were trained to work at the facility recognised by Koday as the best
(of their)facilities in the world. Yeah, the students were trained to
pick at things till they fell apart, like true scientists. Not to take
anything on face value or because someone said so. Of course once all the
microscopes, the electron microscope, the enlargers, cameras and such were
auctioned off and the course dumbed down to get more warm, fee paying butts
on seats it's reputation slipped.
ISO is determined at a given amount of exposure such that its above
base+fog.
we know this Rand. Fact is the stuff looked fantastic when shot at near +2
stops over it's ISO. Looked great at 180 asa too, but at 50 it blew people
away. Was it marketting? sure was. the 80's was when they were really
ramping that stuff up. Fact remains it was 180 ASA flm and exposed at 50ASA
it was 'over' exposed and looked good. It's not simply a latitude thing,
this is where neg film performs best - on the straight line.
'
I will take my experience and work with people like the multi oscar
winning
Mr. Miranda over you.
hahaha, you dont know me. not even a little.
Heres why. If you are shooting in light sources that
are not what the meter does best then its you issues to know what the
spectral response of the film and meter are in relation what they where
created and tested for in ISO.
he built his own light meters when he realised the purchasable models were
limited?
oh wait, he tested all the films himself and didn't rely on manufacturers
blurb..
ISO is a standard. we have a standard here for shearing sheep. who cares?
But if I compare a standard to a result, I start from the standard. If the
standard says i'm overexposing then that's what that standard says. Even if
the exposure looks substantially better that those who comply with The
Standard.. fact is the standard is just a standard.
So its not really over exposing then is
it?
you're wiggling.
Its properly exposing for the spectral sensitivity of the film to that
light source. If your meter is NOT designed to meter that light then it
would be pretty dumb to count on that being accurate for that light.
tell that to all the people who crowed about the ligh meters in their
Nikon/Canon?minolta/Pentaxes across the world.
So
You probably have to test to determine what those sensitivities are and
the
EXPOSE CORRECTLY.
and when the exposure test shows the film to 180 ASA (american standard) or
100/XX DIN ISO (dont forget the DIN otherwise you're not complying with
ISO!) you're saying it works best exposed to the toe. Like the Standard for
determining speed. Even though speed determination has UTTERLY NOTHING to
do with the aestheric look of the image, it's exposure range or anything
else .. it merely reports the minimum sensitivity point, than that's the
best way to go
sheesh..
..on the toe of the curve.. where the most room for slight variation occur,
where you are relying on the least sensitive part of the film - while
ignoring the steep straight curve off up the sensitivity scale.. where you
could reliably record way more than any paper could take advantage of -
instead you want to work at the weakest point of the film because that's how
the ISO was defined You're argiuing that to CORRECTLY expose a film you
must do that?
As to speed, ISO, ASA or DIN - which one? Ilford or Kodak? they're
different. Maybe I could define an ISO speed point - heck, there must be a
dozen speed defenitions put forward over the years. some didnt even use the
toe at all.
You know you can in many cases just use the right type
of Grey card.
I bought 50 gretag grey cards once for the college and put them under the
densitometer. Ceramic calibration. no 2 were alike. we had blue, green,
yellow, magenta, cyan. photography is a sloppy business
I made 10 grey cards using a laser printer (black carbon on white bond
paper) and 10 grey cards using RC paper, both types were, even between the
two types - infinitely more accurate and showed substantially less colour
shift over time than the 'professional' ones. amazing how something so
simple could be ignored ..
I only have 3 types. Generic grey, Strobe card and a
3200 kelvin card. Then I have a chart of what strobe produce what value
on
each card that I use regularly as well as the same notes for hot lights,
Keno's of most temp, Quartz, tungsten, Plasma (latest coolest thing
developed by a friend of mines brother growing in popularity in the film
world.)
we used plasma years back, it was called carbon arc then . I have about 50
rods in the back yard..
Selenium and what medium? Microfilm no its not good for microfilm.
For paper prints yes its still recommended by the IPI. (image permanence
institute (at RIT) https://www.imagepermanenceinstitute.org
and microfilm was the first to reveal that the original sepia toner (which
worked) had thiourea in it, while the later toner(which didnt work) had
none.. and left the film susceptible to redox blemishes. The guys who made
their name in the photo game didnt like this contradiction so it was
ignored. experiments have shown film and paper both suffer it, paper to a
lesser extent as people often (luckily) didnt wash out all the thiosulfate
fix, and as it decomposed as it does naturally, it formed sulfides which
tone and protect the silver in the paper. people dont like this fact
either. Doesnt agree with what they read.
The insignificant amount of time its take the leaf shutter to open and
close are pretty irrelevant and the way a copal operated negates it.
no, that's a simplification and it's downright wrong. in the example I
gave, at f45 you can expect the shutter fully open 1/2-3 times longer than
at a full shutter exposure. demonstrable, repeatable and a noted aberation
and failing in leaf shutters irrespective of brand. who takes this into
account when they make their exposures? almost no one.
heck, who even tests the contrast of their lenses (beside me?). what effect
does that have on light transmission? 10%, 15%.. adds up but no one really
cares so it gets ignored and mistruths get spread around.
>My Schneider leaf shutter mamiya lenses with seiko shutters at fstop of
2.8
are dead nuts accurate with so little fall of its barely measurable and
yeah, yeah, so are mine.. I've got a 40-400 varotal f4 panavision lens,
concave front and thorium elements.
I've got a Cook
not visible from 1/30th to 1/500th. Slower well I use the camera's focal
plan shutter which is also dead nuts on. I think you are totally
neglecting speed vs distance in the design of the leaf shutter.
time for a link:
http://en.wikipedia.org/wiki/Shutter_%28photography%29
".. but as speeds approach their maximum the shutter is far from fully open
for a significant part of the exposure time"
I just can't fathom the
type of error rates you are claiming and can only imagine an experiment
error or equipment that spend to much time near salt water or the Mines
and
dust of West OZ.
you assume a lot Rand.
Karl Shah-Jenner
(not my birth name)..
