Choosing Film Stock and Light Metering
>Published : 10th May 2005
>I have to shoot something on the 35mm and for the first time I have to be DP. As I have to shoot one night scene and the rest are indoor scenes (very night look with cold moonlight from the window and just a bit of 3200k inside light) is it Ok if I choose Kodak Vision 320T for shooting outside and inside or I need faster stock?
>Also, as I have to measure the light for each shot can someone help me where can I read something more about that on the net please?
>Which Kodak's stock (tungsten balanced) have a larger under/overexposure latitude. I have to think about this in case that I make mistake in light measurement.
>And very basic question. The number 320 is equivalent for ISO 320 film speed? For high-speed (100-150fps) I need faster stock or I can shoot with 320?
>Thank you in advance!
>Maybe you should consider the new Expression 500T 5229 (not the old 5284). It's probably similar in latitude to the 320T, maybe even better, and the graininess might be about the same since it is a new Vision-2 stock while 320T is the older Vision stock. Being 500 ASA, it may be more practical for your night exterior scene.
>How fast a stock you need depends on how large of an area you have to light at night and how big your lights are.
>As you run the camera faster, you need to compensate whether by opening up the f-stop, using more light, or using faster film. Or a combination of those. You'd need another stop of light for 48 fps, two stops for 96 fps, and three more stops for 192 fps. So if you had lit your scene for 500 ASA stock at f/5.6 for 24 fps, then you could run the camera at 192 fps and open up to f/2.0. But that's a lot of light. You may not have the lighting package to allow you to shoot at really high frame rates outside at night.
>David Mullen, ASC
>Thank you so much David.
>Few more questions...
>The high-speed shooting will be close up in studio with some glass and juice so the light shouldn't be a problem.
>And because I'm "pretty much NEW"...If I'm doing a change of speed and doing corrections with T-stops for the light, the shutter angle staying the same isn't? I'm still thinking in the way of SLR-s with ISO/f-stop/shutter (1/xxxx) way for right exposure. The "angle" is new measure element for me. ON 25fps 180 degrees angle is the same as 1/50sec. and 90 degrees is 1/100 or not?
>Can I measure the light with Sekonic L-608 Cine and be sure that I have not burned or underexposed film? As I still haven't see this piece of electroic in my hand I don't know how it's doing metering and wich values I can read on it.
>Yeah...I will shoot with ARRI 435ES with Zeiss Ultra Primes Lenses.
>Thank you once again!
>If I'm doing a change of speed and doing corrections with T-stops for >the light, the shutter angle staying the same isn't?
>Yes, the ANGLE stays where you set it (let's say it's 180 degrees, i.e. a half-circle) but the EXPOSURE TIME is affected by the frame rate, so 25 fps with a 180 degree shutter = 1/50th of a second per frame. 50 fps with a 180 degree shutter = 1/100th of a second per frame.
>ON 25fps 180 degrees angle is the same as 1/50sec. and 90 degrees >is 1/100 or not?
>Yes, because 90 is half of 180.
>As you change the frame rate, you can compensate for the exposure loss by changing the f-stop (iris) or the shutter angle. Changing the f-stop changes depth of field and changing the shutter angle changes the amount of motion blurring. So you could light and shoot the shot at 25 fps with a 45 degree shutter angle and then ramp to 100 fps and compensate for the two-stop loss by changing the shutter angle to 180 degrees -- or you could open up the iris by two stops instead and leave the shutter angle the same.
>David Mullen, ASC
>Thank you for a lot of help!!!
>On the issue of light meters, I'm a compositor preparing for a transition into a vfx supervisor's role. I'd like to equip myself with an incident meter and a spot meter.
>If anyone could make a recommendation regarding which brand and models to purchase, I'd be much appreciative.
Compoistor - Sydney, Australia
>Buy a Spectra Pro-IV incident meter and hold out for the Spectra spot meter. Good spot meters are getting hard to come by these days, don't be wooed by the combo meters, they will end up disappointing you.
>They are also part of the reason that real spot meters are so hard to get.
The DoP Shop
>The new Kodak VISION2 Color Negative Films have been well received, with the excellent tone scale and latitude often being praised.
>The Exposure Index (EI) rating of a motion picture film is based on the manufacturer's testing, and is similar to the speed rating used on films intended for still photography:
Eastman Kodak Company