Jump to content


Photo

lumens & f-stops


  • Please log in to reply
1 reply to this topic

#1 Christian Janss

Christian Janss
  • Basic Members
  • PipPip
  • 36 posts
  • Cinematographer
  • Philadelphia

Posted 22 November 2006 - 11:30 AM

I'm trying to find an equation that links lumens output and the corresponding t-stop. I'll be using 200 ISO film and I'm trying to determine what type of projector I'll need to use to get a certain t-stop on a screen at about 10' - 12'.
If anyone knows where I can find this info on the net I'd be much obliged, I don't have access to a cinematographer's manual.

thanks.
  • 0

#2 Laurent Andrieux

Laurent Andrieux
  • Sustaining Members
  • 1527 posts
  • Cinematographer
  • France

Posted 22 November 2006 - 07:02 PM

First don't mistake beetween lumens and lumination (fc, lux)...

the flux i(n lumen), caracterizes the whole luminous energy provided by a luminar, it wil depend a lot on the enlighted surface.

See, let's take a fresnel lens or an open face projector for instance. You know the f-top, as well as the lumination, will vary according to the enlargment,and depend on whether you provide a flood or spot beam.

The flux doesn't depend on this, since the whole energy remains the same. It just doesn't enlight the same surface...

But there are diagrams that show what lumination you get at a given distance, in different positions (flood, medium flood, spot) for a given projector.You will find them from its manufacturer. Try Ianiro, Arri, Desisti or any other one you know. May be browsing their web sites would be successfull...
  • 0


Glidecam

Paralinx LLC

Ritter Battery

Opal

Willys Widgets

Metropolis Post

Gamma Ray Digital Inc

Aerial Filmworks

Tai Audio

Technodolly

Broadcast Solutions Inc

CineLab

The Slider

Visual Products

Abel Cine

rebotnix Technologies

Wooden Camera

Media Blackout - Custom Cables and AKS

CineTape

Rig Wheels Passport

FJS International, LLC

Paralinx LLC

Glidecam

Willys Widgets

Media Blackout - Custom Cables and AKS

Abel Cine

Broadcast Solutions Inc

Opal

CineLab

Ritter Battery

Metropolis Post

Technodolly

Wooden Camera

Aerial Filmworks

Gamma Ray Digital Inc

Rig Wheels Passport

rebotnix Technologies

The Slider

Visual Products

Tai Audio

CineTape

FJS International, LLC