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newbie 200T notch question


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#1 steve bishop

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Posted 25 July 2007 - 07:22 PM

Hi,
sorry if these questions are old hat. I have been doing research but am slightly confused. I bought a nizo s800 and am trying out a vision 2 200T cart with it. I havent got it developed and telecined yet, but would like to test it accurately.

-I understand that the 200T doesnt have a notch to allow my Nizos800 to use its internal 85 filter.
-It also cant recognise films with speeds higher than 160ASA? am i right?
-and this slight overexposing would be ok, except that there is no internal filter in place and therefore it will be read as 100ASA and too overexposed?

does this mean i should cut a notch in my cart like i've seen on guides and the resulting 1/3rd over exposure would be ok? I dont have an external light meter btw.

many thanks. i have read a few conflicting things on forums so hopefully someone can set it straight.

steve
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#2 Jim Carlile

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Posted 27 July 2007 - 03:40 AM

Hi,
sorry if these questions are old hat. I have been doing research but am slightly confused. I bought a nizo s800 and am trying out a vision 2 200T cart with it. I havent got it developed and telecined yet, but would like to test it accurately.

-I understand that the 200T doesnt have a notch to allow my Nizos800 to use its internal 85 filter.
-It also cant recognise films with speeds higher than 160ASA? am i right?
-and this slight overexposing would be ok, except that there is no internal filter in place and therefore it will be read as 100ASA and too overexposed?

does this mean i should cut a notch in my cart like i've seen on guides and the resulting 1/3rd over exposure would be ok? I dont have an external light meter btw.

many thanks. i have read a few conflicting things on forums so hopefully someone can set it straight.

steve


Hi Steve, I posted a longer and more detailed (confusing) answer at another forum, but in a nutshell:

-- VISION stocks are NOT filter notched. That means you cannot use the internal 85 filter in the camera, you have to use an external 85A, B, or C filter. The thinking was that professional use of negative stocks is with external filters only.

-- The silver Nizos like yours can only read up to 160 ASA tungsten, and 100 daylight.

-- VISION 200T is speed notched for 160T/100D. The notch size is the same. What this means is that many cameras will read it at 100 when the filter pin is pushed in by the notchless cartridge. That's what makes it a "daylight" cartridge. The Nizo is one of those cameras.

-- This means the film is overexposed by one stop (the difference between 200 and 100 ASA is double, thus one stop, because the ASA scale is linear.)

-- Supposedly, the Nizos can 'toggle' back and forth between the 'low' and 'high' ASA (daylight vs. tungsten) of the speed notch. This is done with the filter switch. If you slide the switch to 'b' it retains the 160 ASA. Don't know if this is true, but worth a try-- see if you get a difference when you toggle with the cartridge installed.

-- Without a filter notch, no inline filter is possible. But that has nothing to do with the 100 ASA effective speed. The camera system sets the low ASA automatically by the notchless cartridge, even though the filter is never in place. The reason for this is long and complicated, and has to do with allowing Super cameras to efficiently read a variety of film speeds.

-- You can easily cut a notch in the VISION cartridges. This is the easy way out. If you do, the filter pin in the Nizo stays out, so the meter reads the film at 160 ASA-- the 'tungsten' speed. When you slide the filter in place, the film is still 160 ASA, but because the filter takes away 2/3 stop of light, it effectively makes the film the same thing as 100 ASA.

It's not really 100, it just acts like it is. But this is all done auotmatically by the meter, so you don't have to worry about it.

Cheers!
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#3 Aleksi Martikainen

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Posted 02 September 2009 - 03:16 PM

Im sorry for lifting this up, but Im not sure if I have understood right.

Internal filter off, External 85B used
-> takes away 2/3 stops
-> Camera will read film as 160ASA. ( nizo s800 with 200T )

--> Film will be overexposured only 2/3 stops if I use values that lighting meter tells me?
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#4 Jim Carlile

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Posted 13 September 2009 - 04:08 AM

If the internal filter is pushed aside by a notchless cartridge, the film will be read as ASA 100, not 160. If you then put an 85 over the lens, the camera will still read the film at ASA 100, but open up the aperture by 2/3 of a stop to make up for the light loss caused by the filter. So in effect, you treat the film as if it has a film speed of ASA 64 or so when the meter sets the exposure this way.

If the internal filter is pushed aside by the filter switch instead -- and the cartridge has a filter notch in it, it will be read at the straight ASA 160. If you then slide the filter in place, or put one over the lens, it will cut down the light 2/3 of a stop, so the film is as if it were ASA 100 or so in terms of light sensitivity.

By "as if" ASA 100 or ASA 64, this means that if you were going to use an external meter and wanted identical results to how the Nizo handles the film, then you'd rate the film's speed at these numbers respectively.

Actually, the film is still ASA 200, it's just that the Nizo meter reads it lower because it won't go up that high. And the filters will bump down the effective ASA as well. But that's OK, because negative film responds well to overexposure.

A lot of this is touch and go-- this is analog, for sure -- but it works out fine.

Edited by Jim Carlile, 13 September 2009 - 04:13 AM.

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Technodolly

Glidecam

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Ritter Battery

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rebotnix Technologies

Tai Audio

Media Blackout - Custom Cables and AKS

Visual Products

Metropolis Post