Jump to content


Photo

I have a questions


  • Please log in to reply
10 replies to this topic

#1 Naimah

Naimah

    New

  • Basic Members
  • Pip
  • 4 posts
  • Cinematographer
  • .

Posted 18 August 2016 - 07:52 PM

1) " front element, rear element and iris are parts of what filmmaking tool?

 

2) why is ZEBRA a useful tool in digital cinema?

 

3)what 3 things happen when we switch the scarlet from 4KHD to 2KHD?

 

4)

  • DAY EXT using the Scarlet:   Your stop is f/11 at ISO 320, but you would prefer to shoot at f/2.   How would you make this happen without changing the shutter speed?
  • NIGHT INT using the SR:   You create a WEDGE for your KEY light using a Silk, Bounce Board, and a 300w light.  The meter reads “f/2.5” but the widest

            aperture on the Zeiss 10:1 is f/3.2.  How do we fix the problem?


  • 0




#2 Stuart Brereton

Stuart Brereton
  • Basic Members
  • PipPipPipPip
  • 2656 posts
  • Cinematographer
  • Los Angeles

Posted 18 August 2016 - 11:00 PM

Are these homework questions?


  • 0

#3 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 18986 posts
  • Cinematographer
  • Los Angeles

Posted 18 August 2016 - 11:35 PM

Sounds like homework...

 

Any google search would answer these, though I'm not sure the three things that happen when you switch a Red camera from 4KHD to 2KHD -- obviously it crops the sensor down, which means the field of view of the lens gets narrowed, and the data per frame drops unless you change the compression rate, plus you have the option of higher frame rates, but whether that's two or three or four things, I don't know, and if it's two, then I don't know what the third is.

 

Opening up from f/11 to f/2 is five stops, so either you have to add an ND1.5 filter in front... or change the ISO from 320 to 10, which would probably be a bad idea.... or you change the frame rate from 24 fps to 768 fps, however that loses 5-stops but it's because the shutter time has changed, so that doesn't count.

 

As for the difference between f/2.5 and f/3.2, I know there is a mathematical way of figuring out exactly the exposure difference, but since f/2.5 is a little under f/2.8 and f/3.2 is a little over f/2.8, I'm going to guess and say that this is a one-stop difference that you have to compensate for, so either you find a way of compensating on the camera, maybe by doubling the ISO value, or maybe doubling the wattage of the lamp, use a 650w instead of a 300w lamp, would work, or moving the book light rig closer to the subject or maybe just eliminating the silk and just using the bounce, etc.  Or add a second 300w lamp to the book light rig.


  • 0

#4 Robin R Probyn

Robin R Probyn
  • Basic Members
  • PipPipPipPip
  • 1151 posts
  • Cinematographer
  • Tokyo

Posted 19 August 2016 - 12:43 AM

3... the camera crashes .. :)


  • 0

#5 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 18986 posts
  • Cinematographer
  • Los Angeles

Posted 19 August 2016 - 01:08 AM

2... Engineers discovered the the black and white stripes on the African Zebra were perfect for setting the exposures within the clip and crush point of the signal, so it become common in early television in the 1950's for studios to borrow zebras from local zoos and bring them into stages to help calibrate their cameras...  :rolleyes:


  • 0

#6 Robin R Probyn

Robin R Probyn
  • Basic Members
  • PipPipPipPip
  • 1151 posts
  • Cinematographer
  • Tokyo

Posted 19 August 2016 - 01:46 AM

These also worked in conjunction with the front and back elephants ..referred to in question 1


  • 0

#7 JD Hartman

JD Hartman
  • Basic Members
  • PipPipPipPip
  • 1540 posts
  • Gaffer
  • Edison, N.J. U.S.A.

Posted 19 August 2016 - 06:04 AM

These also worked in conjunction with the front and back elephants ..referred to in question 1

 

Would that be African or Indian Elephants?  Different species altogether.


  • 0

#8 Robin R Probyn

Robin R Probyn
  • Basic Members
  • PipPipPipPip
  • 1151 posts
  • Cinematographer
  • Tokyo

Posted 19 August 2016 - 07:31 AM

Ear we go... 


  • 0

#9 Jay Young

Jay Young
  • Basic Members
  • PipPipPipPip
  • 392 posts
  • Cinematographer
  • Lexington KY

Posted 19 August 2016 - 09:41 AM

 

 change the frame rate from 24 fps to 768 fps

 

 

 

Sounds like a great way to kill 20 seconds


  • 0

#10 John E Clark

John E Clark
  • Basic Members
  • PipPipPipPip
  • 795 posts
  • Other
  • San Diego

Posted 19 August 2016 - 11:50 AM

2... Engineers discovered the the black and white stripes on the African Zebra were perfect for setting the exposures within the clip and crush point of the signal, so it become common in early television in the 1950's for studios to borrow zebras from local zoos and bring them into stages to help calibrate their cameras...  :rolleyes:

 

Say, isn't that one of those early 'induced color' examples as well, when the zebras were put on lunge lines and made to run in a circle real fast, the motion of the zebra pattern induced a 'color' in human vision.


  • 0

#11 Ivon Visalli

Ivon Visalli
  • Sustaining Members
  • 28 posts
  • Cinematographer
  • Los Angeles

Posted 23 August 2016 - 03:41 PM

Rather than losing 2/3 stop by covering the zebras in CTO, they began using tigers.  I think there was a special position created within 600 for those camera ops.


  • 0


Metropolis Post

Willys Widgets

rebotnix Technologies

Quantum Music Works

Abel Cine

Rig Wheels Passport

CineTape

Pro 8mm

Technodolly

Tai Audio

The Slider

Zylight

Glidecam

CineLab

Aerial Filmworks

Ritter Battery

Broadcast Solutions Inc

Visual Products

FJS International, LLC

Paralinx LLC

Willys Widgets

Broadcast Solutions Inc

Pro 8mm

Abel Cine

Ritter Battery

Aerial Filmworks

Visual Products

CineTape

Zylight

Tai Audio

Rig Wheels Passport

rebotnix Technologies

Metropolis Post

The Slider

Technodolly

Glidecam

Paralinx LLC

FJS International, LLC

Quantum Music Works

CineLab