Jump to content


Photo

Lightmeter reading


  • Please log in to reply
6 replies to this topic

#1 solomanpro

solomanpro

    New

  • Basic Members
  • Pip
  • 8 posts
  • Other

Posted 01 November 2005 - 01:44 PM

Hi, I hope you can you help me with this question:

I can only get reading from my lightmeter at 1/60 and 1/125 so, for example if I read at 1/60 an f stop of 2.0 and 3/4, and in 1/125 f1.4 and 3/4. How can I know the reading for the intermediates 1/65 or 1/80 for the bolex? Is there any maths to do this? :(
Thank you!
  • 0

#2 Dickson Sorensen

Dickson Sorensen
  • Basic Members
  • PipPipPip
  • 131 posts
  • Cinematographer

Posted 01 November 2005 - 08:09 PM

Take your f stop and square it then multiply it times the denominator of your shutter speed. To find the same exposure at another shutter speed divide that number by the denominator of the new speed and find the square root of that.

example:

2.8 at 1/60

2.8 X 2.8 x 60 = 470.4

? at 1/30

470.4 /30 = 15.68 Square root =3.96

Hey wait a minute! we know the next f stop is 4 what gives?

The values that are established for markings on lenses 1.4, 2, 2.8,4,5.6,8 and so on are rounded off.

In fact the difference between 1/60 and 1/65 in your problem is only slight and may not be enough to worry about unless your are doing very critical work. Just crack the lens open a hair to compensate.
  • 0

#3 solomanpro

solomanpro

    New

  • Basic Members
  • Pip
  • 8 posts
  • Other

Posted 02 November 2005 - 04:11 AM

Thank you Dickson!!
Today I´m going to shoot some footage for the first time( I´m too excited!). Thank you for your replay! It´s going to be a big help!
  • 0

#4 Dimitrios Koukas

Dimitrios Koukas
  • Sustaining Members
  • 569 posts
  • Cinematographer
  • Athens, Greece, London UK

Posted 02 November 2005 - 06:09 AM

Thank you Dickson!!
Today I´m going to shoot some footage for the first time( I´m too excited!). Thank you for your replay! It´s going to be a big help!


Make the calculations by Sorensen,before u go for shooting and make your own chart.
Dimitrios
  • 0

#5 solomanpro

solomanpro

    New

  • Basic Members
  • Pip
  • 8 posts
  • Other

Posted 02 November 2005 - 08:22 AM

Thank you Dimitrios.

I´m doing a table with the f stops at 1/60 ,1/65 and 1/80. After developing I´ll tell you my results. By the way, today the weather in London is horrible and the maximum reading I can get is 5.6... so for smaller times I have to close a lot the iris.Do you think I can get anything with this or everything is going to be dark and blured?

Edited by luismpla, 02 November 2005 - 08:24 AM.

  • 0

#6 Dimitrios Koukas

Dimitrios Koukas
  • Sustaining Members
  • 569 posts
  • Cinematographer
  • Athens, Greece, London UK

Posted 03 November 2005 - 12:48 PM

Thank you Dimitrios.

I´m doing a table with the f stops at 1/60 ,1/65 and 1/80. After developing I´ll tell you my results. By the way, today the weather in London is horrible and the maximum reading I can get is 5.6... so for smaller times I have to close a lot the iris.Do you think I can get anything with this or everything is going to be dark and blured?


Is everything outdoors?
I believe 5.6 isn't bad at all, actually for many lenses is where they have the best resoulution!
Dimitrios Koukas
  • 0

#7 solomanpro

solomanpro

    New

  • Basic Members
  • Pip
  • 8 posts
  • Other

Posted 02 December 2005 - 01:33 PM

It was PERFECT!!!
My camera works and the readings were accurate! I tried doing three different readings but there were not so much difference between them. In fact my favourites were without adapting the Bolex shutter to the lightmeter reading. What i get with the sekonic was perfect. And the images were amazing. I shot it with a Fuji 64 and the readings were from 0.4 to 5.6, calculating the intermediates in some takes I was able to shoot inside my house. Video is great but when you see just one frame of film everything change, film have the magic that video lacks. Maybe is not reality like Godard said but it´s a beautiful reality in itself. I LOVE FILM!!!
  • 0


Tai Audio

Rig Wheels Passport

Paralinx LLC

Metropolis Post

Visual Products

Gamma Ray Digital Inc

Broadcast Solutions Inc

Media Blackout - Custom Cables and AKS

Wooden Camera

Aerial Filmworks

Ritter Battery

CineTape

FJS International, LLC

Opal

CineLab

Glidecam

Willys Widgets

rebotnix Technologies

Technodolly

Abel Cine

The Slider

Ritter Battery

Tai Audio

rebotnix Technologies

Metropolis Post

Opal

Gamma Ray Digital Inc

Aerial Filmworks

CineTape

Glidecam

Wooden Camera

Willys Widgets

CineLab

The Slider

Rig Wheels Passport

Visual Products

Paralinx LLC

Technodolly

FJS International, LLC

Media Blackout - Custom Cables and AKS

Abel Cine

Broadcast Solutions Inc