Jump to content


Photo

Alexa with 16mm Ultraprime issue


  • Please log in to reply
4 replies to this topic

#1 Bruce Greene

Bruce Greene
  • Basic Members
  • PipPipPipPip
  • 621 posts
  • Cinematographer
  • Los Angeles

Posted 11 September 2015 - 11:52 AM

I recently shot a film with the Alexa and Ultra Prime lenses.

My issue is flare with the 16mm lens. I noticed a flare in the center of the image and tried to flag the lens, but it did not help. I then discovered that the flare is exactly a circle in the center of frame. It's caused by a bright background reflecting off the sensor, back to the rear element of the lens, then back to the sensor as a circle of flare over the cross hairs.

This will be tough to fix in DI I think, but doable.

My question: Is there a lens set that does not exhibit this issue?
  • 0

#2 Kenny N Suleimanagich

Kenny N Suleimanagich
  • Basic Members
  • PipPipPipPip
  • 902 posts
  • Cinematographer
  • New York

Posted 11 September 2015 - 02:06 PM

I wonder if Master Primes would have this happen?
  • 0

#3 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 20254 posts
  • Cinematographer
  • Los Angeles

Posted 11 September 2015 - 02:17 PM

I used that lens for some shots in "90 Minutes in Heaven" on the Alexa and didn't notice this, maybe I got lucky.
  • 0

#4 Bruce Greene

Bruce Greene
  • Basic Members
  • PipPipPipPip
  • 621 posts
  • Cinematographer
  • Los Angeles

Posted 11 September 2015 - 06:06 PM

noticed the effect a few times. I'll try to look for an example frame, but it'll take a little while to find in the dailies...
  • 0

#5 Tyler Purcell

Tyler Purcell
  • Sustaining Members
  • 4281 posts
  • Other
  • Los Angeles

Posted 11 September 2015 - 11:42 PM

I have similar problems with my Rokinon lenses and my Blackmagic Pocket camera. There is image refraction happening on the back element of glass. It's hard to see if you aren't looking for it. I've never noticed it on any other camera I've shot with.
  • 0


New Pro Video - New and Used Equipment

Wooden Camera

Aerial Filmworks

Willys Widgets

Technodolly

CineLab

Glidecam

Abel Cine

Metropolis Post

Tai Audio

The Slider

CineTape

Paralinx LLC

Ritter Battery

Broadcast Solutions Inc

Media Blackout - Custom Cables and AKS

rebotnix Technologies

FJS International, LLC

Rig Wheels Passport

Gamma Ray Digital Inc

Visual Products

FJS International, LLC

Willys Widgets

Glidecam

Ritter Battery

Aerial Filmworks

Rig Wheels Passport

Tai Audio

Paralinx LLC

Broadcast Solutions Inc

The Slider

Abel Cine

Technodolly

Gamma Ray Digital Inc

Wooden Camera

New Pro Video - New and Used Equipment

CineLab

rebotnix Technologies

CineTape

Media Blackout - Custom Cables and AKS

Visual Products

Metropolis Post