Jump to content


Photo

Magnetic HMI ballasts and 23.98fps


  • Please log in to reply
2 replies to this topic

#1 Bryce Lansing

Bryce Lansing
  • Basic Members
  • PipPip
  • 73 posts
  • Cinematographer

Posted 28 May 2010 - 10:02 PM

I got my Arri 1.2k HMI Par with magnetic ballasr, fully aware of the flicker issues. But now I'm a little confused...

I read that 24fps at 180 degree shutter (1/48th) was flicker free, but that 23.98 at 180 degree shutter was unsafe..

So first I test the Canon 7d at 24p (which is really 23.98 right?) at 1/50th, and sure enough, rolling bars. 1/30th, 1/40th, and 1/60th looked fine.

Then I tested my HVX200a, 24p (23.98 as well right?) at 180 degree shutter, and it from what I could see it looked completely fine. I know it has a global shutter so I wasn't expecting rolling bars, but it wasn't flickering at all either.

Why is this? Is 1/48th a flicker free shutterspeed with the HVX? Or am I not seeing a very subtle flicker?
  • 0

#2 timHealy

timHealy
  • Basic Members
  • PipPipPipPip
  • 1262 posts
  • Other
  • New York

Posted 29 May 2010 - 04:52 PM

where are you and what kind of electricity are u juic'in this baby with?
  • 0

#3 David Winters

David Winters

    New

  • Basic Members
  • Pip
  • 2 posts
  • Cinematographer

Posted 20 June 2010 - 09:51 PM

I got burned with rolling bars on a Red One M shoot. 23.98 1/48th, shooting 2 passes of a scene to be compt'ed together. In the end we cleaned it up in post, but now I shoot a test, wide lens on a even light surface to verify. If I don't have time to test I shoot at 1/40th or 1/60th. Some cameras appear to be more sensitive vs others. I've never personally experienced rolling bar issues on 3-CDD systems at 23.98 1/48th, but I have had problems with rolling shutter CMOS cameras. However, most of the time it's so subtle that it's not an issue.

Hope this helps.
  • 0


Ritter Battery

Gamma Ray Digital Inc

Technodolly

CineLab

Paralinx LLC

The Slider

Aerial Filmworks

Glidecam

Visual Products

Metropolis Post

Wooden Camera

Rig Wheels Passport

CineTape

Media Blackout - Custom Cables and AKS

FJS International, LLC

New Pro Video - New and Used Equipment

rebotnix Technologies

Abel Cine

Willys Widgets

Tai Audio

Broadcast Solutions Inc

Tai Audio

Wooden Camera

Gamma Ray Digital Inc

Technodolly

The Slider

Aerial Filmworks

Metropolis Post

Abel Cine

Willys Widgets

FJS International, LLC

CineTape

Broadcast Solutions Inc

Rig Wheels Passport

Ritter Battery

Paralinx LLC

Glidecam

CineLab

Visual Products

New Pro Video - New and Used Equipment

rebotnix Technologies

Media Blackout - Custom Cables and AKS