Unless you have a reason to believe that a manufacturer doctored data, ISO film speed is the speed you ALWAYS use when metering. That's the explanation they need. That's the end of story.
64 iso
IC 0,5
Devloped 20° D76 1+1 6'30sec
My understanding was also that prior to 1960 most cameras/people did not have light meters and were estimating exposure. There was more danger of underexposure in those circumstances. Meters were becoming more common in the 60's and exposure could be determined more accurately than previously. Thus the need for the safety factor could be removed and the film speeds increased.
The change had nothing to do with the film, but with the rise of more accurate metering.
Exactly. This is exactly what I was asking, because not all manufacturers adhere to the ISO standard. Foma 400 never reaches its stated ISO speed even in Microphen, for example. And that is what I was asking: whether Acros offers honest ISO 100 or not, and in what developers.
There was no need to bring exposure into the conversation, as Matt was suggesting. Photrio loves going on tangents in threads, which can be fun at times, but it's not always helpful.
You are being entirely too forgiving of the writers who say that Delta 3200 and TMax P3200 have no ISO. They say that because the ISO is not printed on the box, and they are too lazy to read the datasheet, where it couldn't be clearer. One wonders where they find the recommended developers and development times for processing the films when shot at higher EIs. Probably the MDC. God forbid that the have to read the datasheets.Perhaps not by folks on this forum, but there indeed is confusion out there about the difference between ISO and personal E.I. I have seen web reviews that, for example, claim that Delta 3200 and Tmax P3200 have NO ISO, though the manufacturers list it in the data sheets. What they may be getting at is that because these films were designed to be pushed, the reviewer feels that they don't have enough contrast when shot at ISO speed.
Just read the fine print on the Tech sheets. Delta 3200 does have a "official" speed rating around 1000. But it was designed to be usable at higher speeds with only moderate loss to shadow detail. I personally rate it at 800 for sake of PMK pyro and full scale tonality. The case with TMZ is analogous, and also confessed in fine print. So both of these are representative instances of the nominal speed on the box being a marketing ploy - not a falsehood, but certainly a stretching of the rubber band.
You are being entirely too forgiving of the writers who say that Delta 3200 and TMax P3200 have no ISO. They say that because the ISO is not printed on the box, and they are too lazy to read the datasheet, where it couldn't be clearer. One wonders where they find the recommended developers and development times for processing the films when shot at higher EIs. Probably the MDC. God forbid that the have to read the datasheets.
Just read the fine print on the Tech sheets. Delta 3200 does have a "official" speed rating around 1000. But it was designed to be usable at higher speeds with only moderate loss to shadow detail. I personally rate it at 800 for sake of PMK pyro and full scale tonality. The case with TMZ is analogous, and also confessed in fine print. So both of these are representative instances of the nominal speed on the box being a marketing ploy - not a falsehood, but certainly a stretching of the rubber band.
EI not ISO. The nominal speed should be what the ISO would be if it was done to the ISO standard. Odds are they didn't complete some part of the standard like testing film from multiple batches over the course of a number of months. Every other value would have to be an EI even if they did.
"It was determined in a manner published in ISO standards." sounds pretty clear to me. Perhaps you think the statement is ambiguous.
It said in a manner. If the standards are not followed exactly you cannot include the ISO prefix. Kodak probably only followed the sensititetric exposure and processing part, which is enough to achieve a film speed value. If they did the work, they would have included the prefix.
Well, I already implied it. I mainly use Delta 3200 only for moderate contrast scenes, and at a speed of 800. That way I'm only skating at the safe center of the ice rink, and not on either the toe or shoulders. And staining pyro development also helps with respect to retaining highlight detail.
If I want a long scale film with some high speed capacity, more suitable for higher contrast scenes, I'd rather shoot TMax 400 at 800 instead, and settle for a stop of bold shadow loss, but with everything above that having crisp gradation. But really, TMY at actual 400 speed is only one stop slower than what I find to be the real-world speed of D3200, namely 800. It just enjpy fooling around with the different looks of various films. TMax 400 is way more versatile, however, being much finer grained and available in sheet film version too.
So how well do we do in explaining these matters to the beginner? Pretty badly I'd say. If someone manages to use a few easy to understand sentences that encapsulate a necessary concept well in order to enable the newcomer to learn and move forward at a pace commensurate with his existing knowledge the thread moves on quickly to "confusion freeway" where we undo whatever good work was doneChuck,
Once a beginner spends a weekend on photrio, I suspect they'll need some kind of a "jargon detox" to clean up their minds before they're able to ingest new information.
There's another similar confusion that hits everyone: the pushing and pulling. 9 out of 10 believe that pushing happens by tweaking the ISO dial on a camera. They show up at the lab here proclaiming "here! I pushed this film two stops! now develop it!".
So how well do we do in explaining these matters to the beginner? Pretty badly I'd say. If someone manages to use a few easy to understand sentences that encapsulate a necessary concept well in order to enable the newcomer to learn and move forward at a pace commensurate with his existing knowledge the thread moves on quickly to "confusion freeway" where we undo whatever good work was done
We never test whether what we have told the beginner has been understood or not that I have seen
pentaxuser
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