"Real" ISO values of sheet film.

removed account4 · Jan 9, 2011

i have never told anyone what to do ...

i find it remarkable that someone could twist what i said around
to even think that i said that ...

i don't think there is any right or wrong way to make photographs...
but it seems others have different opinions on that, and if someone doesn't
do things their way, they need not participate in the technical forums ...

Q.G. · Jan 9, 2011

Out of interest, Jnanian and Bettersense: what was the intention of telling someone asking how to arrive at the true ISO of film that you don't use a meter (and ISOs)?

(Saw what Bettersense wrote again, Mark. If you are still looking for something that could be interpreted as an insult, how about his "who cares?"? )

Stephen Benskin · Jan 9, 2011

I think I confused the two postings. I have also apparently confused jnanian with someone else who wrote a very insulting "reason for deletion of post" comment in another thread "Reason: No point wasting time."

My apology to jnanian.

removed account4 · Jan 9, 2011

Q.G.

if you read what i said on page 2
i answered the questions about how
manufacturers arrive at box speed.
but unfortunately from that time on, stephen b has
had issue with pretty much everything i have said in this thread
because i said iso is calculated in a lab setting, which i don't consider "real life" ...

later on on page 6 when ic-racer asked bettersense
if he took random exposures &C .. i said i did that, and do it often.
it seemed that the conversation had waned
to a different topic, not " what is box speed / "real iso" of sheet film "
but something else.

my intent was to illustrate that film has a certain forgiveness,
and all is not lost if someone finds themselves in a jam, without a working
meter and maybe only 1 shutter speed and 1 aperture ...
it might not a lost cause ...

Sirius Glass · Jan 9, 2011

2F/2F said:
Sirius Glass said:

MattKing said:

... but I would agree that this thread is a technological thread, and do wonder why, for example, someone who rarely uses a meter would be concerned about "real" speed values for film.

Click to expand...

That would be a theological exposure argument rather than a technological argument.

Steve

Click to expand...

I don't use a meter perhaps half the time I shoot, and practically never with small format or digital. That doesn't mean I don't decide an exposure to use based on my best educated guess. I still want to know how fast my film is (though I find that box speed generally works just fine unless using the Zone System, which I do not do all that often now that I am shooting less sheet film than ever). Not using a meter does not mean that one does not want a decent exposure.

I was being rhetorical. I sometimes do not use a meter. [Nota bene: ]

Steve

markbarendt · Jan 9, 2011

Q.G. said:
how about his "who cares?"? )

I know I don't care what the real number is, I just care about what works for me. That's not an insult, just a fact.

It also appears neither did the Westons as a hard line issue.

Stephen Benskin said:
Edward and Brett Weston both rarely used meters. There's a great deal to discuss about the level of precision required to make a quality photograph.

Stephen is right.

brianmquinn · Jan 9, 2011

Back to the main subject.
The fact is film does not have a REAL speed.
If you do all the work from shutter click to final print ISO means nothing.

You use your cameras, lenses and developing technique to determine what works for you.
Some shooters are obsessed with shadow detail and some with the mood of the shot. Many classic shots have VERY dark shadows and that is what MAKES the print have the impact.

The whole reason for the ISO standard for determining film speed was to produce an average working speed. If you shoot at that speed you will get “useful” negatives. If you send your film out for developing they need to know how you rated the film. The ISO standard tells them how to develop. The lab can push or pull if you tell them to do so. BUT the fact is if they hear nothing from the shooter they develop as per ISO and film maker standards.

2F/2F · Jan 9, 2011

brianmquinn said:
The ISO standard tells them how to develop. The lab can push or pull if you tell them to do so. BUT the fact is if they hear nothing from the shooter they develop as per ISO and film maker standards.

There is an exception: the "3200" films. They are ISO 1000, but most labs will develop them at times for 3200 because that is how most rate them.

brianmquinn · Jan 9, 2011

Not to offend 2F/2F but that is what I said. The lab develops as per box speed.

Stephen Benskin · Jan 10, 2011

brianmquinn said:
Not to offend 2F/2F but that is what I said. The lab develops as per box speed.

I ran a couple of b&w film departments in high end commercial labs, and I developed to a CI.

2F/2F · Jan 10, 2011

brianmquinn said:
Not to offend 2F/2F but that is what I said. The lab develops as per box speed.

You said to ISO standards. "Box speed" on the 3200 films is not an ISO film speed.

brianmquinn · Jan 10, 2011

QUOTE:
I ran a couple of b&w film departments in high end commercial labs, and I developed to a CI.

MY REPLY:
How do you develop to a CI if you are given a roll of film without any infomation?

brianmquinn · Jan 10, 2011

2F/2F said:
You said to ISO standards. "Box speed" on the 3200 films is not an ISO film speed.

Good point. But ISO standards do asks the film maker HOW they arrived at the film speed. That includes developer used , time , etc

I am not trying to argue but just offer a GOOD reason for the ISO standard and or the published time for film developer combos.

Stephen Benskin · Jan 10, 2011

brianmquinn said:
How do you develop to a CI if you are given a roll of film without any infomation?

I didn't say no information. Normal denotes average conditions. I assumed a 2.2 log luminance range, 0.40 flare, and a aim negative density range of 1.10.

removed account4 · Jan 10, 2011

you must have run a tight ship !

i knew people at a handful of commercial labs ( 1980s/1990s ) who told me
it was business as usual to batch developed films and they did it all the time.
(it was a common practice to not process film at box speed.)
kodak suggests films that are shot 1 stop over / under (normal) exposure to be processed as "normal".

is this as common practice as they suggested ?

brianmquinn · Jan 10, 2011

Stephen Benskin said:
I didn't say no information. Normal denotes average conditions. I assumed a 2.2 log luminance range, 0.40 flare, and a aim negative density range of 1.10.

You use the word ASSUMED.
If you assume you will be correct MOST of the time.
If you are posting here I do not doubt you are a pro and you can speak with authority. But still I feel that running the whole shot from shutter click to final print is the best way to get what you desire.

Stephen Benskin · Jan 10, 2011

At one of the labs, I was able to have a customized Refrema Olympic built. It was probably the best commercial processor in the country. I had a calibrated EG&G sensitometer (still do, I used my own), and everything was based on sensitometric principles. I can't speak for other labs, but I don't adhere to the concept of developing for speed. The development is based upon the relationship of the subject to the printing conditions. Speed is a product of the film/developmental process. I've written a paper on developmental models that goes into more detail.

Stephen Benskin · Jan 10, 2011

brianmquinn said:
You use the word ASSUMED.
If you assume you will be correct MOST of the time.
If you are posting here I do not doubt you are a pro and you can speak with authority. But still I feel that running the whole shot from shutter click to final print is the best way to get what you desire.

I do too. In my personal work, no body touches nothing. However, if you were to come to any lab I worked at, I could have shown you the film curves from our testing. I believed in open communication with the clients.

At one point, I tried getting more information from the clients, but some of the customers were really suspicious and freaked out.

Most of the time, the customers couldn't provide usage information about their shooting conditions even if they wanted to. As 2.20 is the average log luminance range and has a standard deviation of 0.38, the assumption of normal is correct at least 68% of the time (a little statistical humor).

brianmquinn · Jan 10, 2011

"is correct at least 68% of the time (a little statistical humor). "

NICE

I worked in retail lab long enough to know you are correct.

brianmquinn · Jan 10, 2011

When you and I think about it isn't what we are aiming at the same thing as Kodak/ Ilford / etc is aiming at? A box speed on their film?

markbarendt · Jan 10, 2011

brianmquinn said:
When you and I think about it isn't what we are aiming at the same thing as Kodak/ Ilford / etc is aiming at? A box speed on their film?

I'd actually say that a box speed "range" is what I'm looking for, i.e. "can be exposed over the range EI 50/18–800/30"

A film speed range allows me to make better artistic choices. Having a range allows me to choose a film that will allow me to shoot at both a certain aperture and a certain speed. That's huge because it means I don't have to switch films to maintain those choices when I turn the camera 90 or 180 degrees.

With a range I can maintain a certain DOF and control the amount of motion blur I want across a whole series of shots by using the latitude of the film and my enlarger to compensate for the changes in film exposure.

In my mind aperture and shutter speed choices always trump film speed. The effects aperture and shutter speed have on the subjects in the photo are tough to replicate or compensate for in an enlarger. Exposure differences are easy to fix by comparison.

ic-racer · Jan 10, 2011

I am reading a number of posts that are indicate confusion between development and speed.

I would like to emphasize that Jones used film processed to a number of different gammas and his results demonstrated a pretty good SINGLE speed point (using 0.3G) in spite of developing to different conditions. Again, just to emphasize the point, increased development did not make the film faster.

Chuck_P · Jan 10, 2011

Since the fog level increases with development time, the effect could move the toe of the curve to the left on the log exposure scale (indicating an increase in speed), but I have only seen this with my "N+2" development curves, N+1 development did not increase fog enough. The reverse is true with minus development as decreased fog occurs with enough decreased development.

markbarendt · Jan 10, 2011

ic-racer said:
I am reading a number of posts that are indicate confusion between development and speed.

I would like to emphasize that Jones used film processed to a number of different gammas and his results demonstrated a pretty good SINGLE speed point (using 0.3G) in spite of developing to different conditions. Again, just to emphasize the point, increased development did not make the film faster.

AA also found that same thing with + & - development as I remember.

I'd like to be clear that the latitude of a film that I speak of isn't based on shooting to "a" speed point, it's simply a limit at one end of the range.

Stephen Benskin · Jan 10, 2011

The pdf is a paper I wrote, "What is Normal? A Developmental Model for B&W Film Processing." While it doesn't address the speed/processing relationship, it does explain my conceptual approach to processing.

"Real" ISO values of sheet film.

Attachments

Privacy & Transparency

Privacy & Transparency