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#1 Tebbe Schoeningh

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Posted 06 August 2007 - 01:06 PM

Hi!

Reading the ASC-Article about "Die Hard 4.0" i got confused by the description about the ISO Rating of the filmstock Simon Duggan was using on that film.

"The Cinematographer shot the picture on two Kodak Vision2 stocks, 500T 5218 (often pushed one stop and rated at ISO 800) for studio and night work and 250D 5205 (rated at ISO 200) for day-exterior work."

Could somebody explain me what is this ISO Rating about? I thought that pushing the film by one stop, the ISO doubles (ergo 500T would be 1000T) is that right? :blink:

Thank you very much!

Tebbe
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#2 Jan Weis

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Posted 06 August 2007 - 02:11 PM

Hi!

Reading the ASC-Article about "Die Hard 4.0" i got confused by the description about the ISO Rating of the filmstock Simon Duggan was using on that film.

"The Cinematographer shot the picture on two Kodak Vision2 stocks, 500T 5218 (often pushed one stop and rated at ISO 800) for studio and night work and 250D 5205 (rated at ISO 200) for day-exterior work."

Could somebody explain me what is this ISO Rating about? I thought that pushing the film by one stop, the ISO doubles (ergo 500T would be 1000T) is that right? :blink:

Thank you very much!

Tebbe


I think youre confusing the word "pushing" with "rating". When they say the filmstock is often ''pushed'' what they mean is that its chemically pushed (processed for a longer time). When you rate this stock at 800 and because of (for example) a low light situation, then to get more detail out of the film, you ask the lab to ''push'' it to get that detail.

I hope I helped in someway...but you experts please feel free to correct me or better yet explain the process better.

/Jan
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#3 David Mullen ASC

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Posted 06 August 2007 - 04:15 PM

He's exposing a 500T stock at 400 ASA for some slight extra density, so for a one-stop push, he'd be setting his light meter to 800 ASA.

The manufacturer's rating is just a suggested rating -- you may prefer the results of using a different rating. Plus the difference between 500 ASA and 400 ASA rating is only something like 2 printer light points, nearly neglible.
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#4 Tebbe Schoeningh

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Posted 06 August 2007 - 08:22 PM

Thanks for the fast replies! Now I understand the rating-thing ;)

Tebbe
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#5 Reinis Traidas

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Posted 12 August 2007 - 08:44 PM

He's exposing a 500T stock at 400 ASA for some slight extra density, so for a one-stop push, he'd be setting his light meter to 800 ASA.

The manufacturer's rating is just a suggested rating -- you may prefer the results of using a different rating. Plus the difference between 500 ASA and 400 ASA rating is only something like 2 printer light points, nearly neglible.


Wait, I don't get it. If you're shooting 500 and set your meter to 800, isn't that going to underexpose slightly? The meter is going to give you reading thinking that your film is more sensitive where it actually isn't. If you wanted everything a stop over normal exposure, you'd probably need to reduce the ISO reading on the meter by 100%? Say if you're shooting ISO 400, set the meter to ISO 200 and everything will be a stop over, or pushed a stop. Does that sound about right? Please tell me if I've got this wrong.
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#6 Ignacio Aguilar

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Posted 12 August 2007 - 09:02 PM

Wait, I don't get it. If you're shooting 500 and set your meter to 800, isn't that going to underexpose slightly?


Yes, that's why you need to ask your lab to push a stop when they develope it. You would get a properly exposed negative, a bit more dense because of the 1/3 of a stop overexposure, and a bit more contrast, grain and color saturation. If you don't push a 500T negative rated at 800 ASA, you would have a 2/3 of a stop underexposure.

If you don't want to overexpose it slightly, you just would set your meter at 1000 ASA and ask the lab to force develope it. The grain will be more visible and the blacks will be milkier. Of course, you can ask for a 2/3 of a stop push and rate it a 800.

If you are shooting a 500T stock and you rate it at 250 ASA, you would be overexposing it by one stop. You would have a very dense negative if developed normally, or you could ask the lab to pull accordingly to your original 250 ASA exposure (pulling does reduce contrast and softens the colors).
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#7 Reinis Traidas

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Posted 13 August 2007 - 06:26 AM

If you don't want to overexpose it slightly, you just would set your meter at 1000 ASA and ask the lab to force develope it. The grain will be more visible and the blacks will be milkier. Of course, you can ask for a 2/3 of a stop push and rate it a 800.


I get it now, thanks. I have yet to experiment with all this, though at this time I don't see any reason why I should make the lab pull or push when developing - film has an excellent dynamic range and you can quite literally push it in post to get more detail out of the dark areas. Especially with hi-res DI scans and a proper grading facility.
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Rig Wheels Passport

Visual Products

Aerial Filmworks

The Slider

Glidecam