Jump to content


Photo

Switar 100 POE - manual exposure compensation on zoom?


  • Please log in to reply
1 reply to this topic

#1 Richard Ashrowan

Richard Ashrowan

    New

  • Basic Members
  • Pip
  • 4 posts
  • Cinematographer

Posted 16 May 2012 - 04:51 AM

I'm shooting with a Vario Switar 100 POE with a Bolex RX5, but the built in exposure meter of the lens is dead (tried new batteries, but the contact seems to have been badly corroded away, so no joy), which means I'm working from a manual exposure meter. I wondered if any exposure compensation might be required when closely zoomed in? I would assume being zoomed in reduces the light entering the lens, so would have to open it up a little? Does anyone have any experience of this?

Sadly, I'm not right now in a position to develop any test footage.

I'm using a bolex lightmeter (which has built in compensation for the reflex viewfinder), taking incident lightreadings outdoors, mainly shooting high contrast light/dark subjects. Shooting on double-x 7222 b/w neg stock.

Many thanks,
Richard
  • 0

#2 Boris Belay

Boris Belay
  • Basic Members
  • PipPipPip
  • 210 posts
  • Other
  • Brussels, Belgium

Posted 23 May 2012 - 06:16 AM

Hi Richard, The Vario-Switar 100 POE has a constant aperture (max f : 1,9), which means there is no light loss whether zoomed in or out (one of the design features of a lot of cinema zoom lenses over cheaper photo lenses).

If anything, you may want to expose your film 1/2 of an f stop slower to compensate for light loss of the optical elements (for some reason Kern does not give T stops which account for that) and for the ageing of the lens. Film will be able to handle this very slight over exposure in any case.
  • 0


Willys Widgets

Tai Audio

Paralinx LLC

The Slider

Glidecam

Wooden Camera

FJS International, LLC

rebotnix Technologies

Technodolly

Gamma Ray Digital Inc

Media Blackout - Custom Cables and AKS

Metropolis Post

Broadcast Solutions Inc

Opal

Aerial Filmworks

Rig Wheels Passport

CineTape

CineLab

Ritter Battery

Abel Cine

Visual Products

CineLab

CineTape

Aerial Filmworks

Metropolis Post

Visual Products

Tai Audio

Abel Cine

Rig Wheels Passport

The Slider

Opal

rebotnix Technologies

Ritter Battery

FJS International, LLC

Technodolly

Broadcast Solutions Inc

Paralinx LLC

Glidecam

Wooden Camera

Willys Widgets

Media Blackout - Custom Cables and AKS

Gamma Ray Digital Inc