Over-Crank 60fps : Light Loss? at DVinfo.net

Go Back   DV Info Net > Sony XAVC / XDCAM / NXCAM / AVCHD / HDV / DV Camera Systems > Sony XDCAM EX Pro Handhelds

Sony XDCAM EX Pro Handhelds
Sony PMW-300, PXW-X200, PXW-X180 (back to EX3 & EX1) recording to SxS flash memory.


Reply
 
Thread Tools Search this Thread
Old May 12th, 2009, 03:48 PM   #1
Major Player
 
Join Date: Nov 2008
Location: Santa Monica, CA
Posts: 318
Over-Crank 60fps : Light Loss?

ok, help me do the math. if i'm shooting 24P at 1/48th or 180 degree shutter and i decide to over-crank to 60fps with "equivalent" shutter speed of 1/120th, am i going to loose 3 stops a light? 1.5 for frame rate and 1.5 for the shutter speed difference. right? so, if i'm lighting an interior and i normally shoot at lets say f/2.0, i'd have to light for a f/5.6 in case i decided to over-crank to 60fps. it that right? please no comments on pumping up gain or filter light loss to consider.

thanks,
Mike
Michael B. McGee is offline   Reply With Quote
Old May 12th, 2009, 05:47 PM   #2
Trustee
 
Join Date: Nov 2005
Location: Sydney Australia
Posts: 1,570
Yes, you will loose light.
If you keep the shutter angle constant then the time the shutter is open for is function of the fps. Double the fps and the time the shutter is open halves hence half the light.
Bob Grant is offline   Reply With Quote
Old May 12th, 2009, 06:11 PM   #3
Regular Crew
 
Join Date: Dec 2007
Location: Port Coquitlam BC Canada
Posts: 179
Why not confirm your theories by doing a little test with the camera's spot meter activated. I just did a bit of a test myself and set the EX1 @ 720P 24 and 1/48th shutter. I cranked the iris until the spot meter read an even 70%. Then I changed shutter speed to 1/120th sec. and enabled over cranking to 60 fps. The spot meter went down to 42%. I never touched the iris or moved the camera.

- Don
Don Greening is offline   Reply With Quote
Old May 16th, 2009, 01:00 PM   #4
Major Player
 
Join Date: Nov 2008
Location: Santa Monica, CA
Posts: 318
Quote:
Originally Posted by Don Greening View Post
Why not confirm your theories by doing a little test with the camera's spot meter activated. I just did a bit of a test myself and set the EX1 @ 720P 24 and 1/48th shutter. I cranked the iris until the spot meter read an even 70%. Then I changed shutter speed to 1/120th sec. and enabled over cranking to 60 fps. The spot meter went down to 42%. I never touched the iris or moved the camera.

- Don
oh boy, does 70% -(minus) 42% = 3 stops?
Michael B. McGee is offline   Reply With Quote
Old May 16th, 2009, 03:47 PM   #5
Inner Circle
 
Join Date: Apr 2006
Location: Wales
Posts: 2,130
No, you'll only lost just over a stop as the frame rate is irrelevant, it's just the shutter speed that matters. Each frame is exposed for whatever the shutter speed is set to, down to a minimum of the frame rate (ie you can't have 1/25th second at 50fps!)
So looking at it another way, if you set 1/48th shutter it'd be the same exposure for each frame if you shot at 24P or 60P.
Steve
Steve Phillipps is offline   Reply With Quote
Old May 16th, 2009, 04:49 PM   #6
Major Player
 
Join Date: Nov 2008
Location: Santa Monica, CA
Posts: 318
Quote:
Originally Posted by Steve Phillipps View Post
No, you'll only lost just over a stop as the frame rate is irrelevant, it's just the shutter speed that matters. Each frame is exposed for whatever the shutter speed is set to, down to a minimum of the frame rate (ie you can't have 1/25th second at 50fps!)
So looking at it another way, if you set 1/48th shutter it'd be the same exposure for each frame if you shot at 24P or 60P.
Steve
your 1/48th statement is false. if you set your camera to shoot at 60fps then 1/60th (360 degree) would be your slowest shutter speed. you're right about frame rate though. i just figured it out. thanks to all who answered.

-Mike
Michael B. McGee is offline   Reply With Quote
Old May 16th, 2009, 06:00 PM   #7
Inner Circle
 
Join Date: Apr 2006
Location: Wales
Posts: 2,130
Quote:
Originally Posted by Michael B. McGee View Post
your 1/48th statement is false. if you set your camera to shoot at 60fps then 1/60th (360 degree) would be your slowest shutter speed. you're right about frame rate though. i just figured it out. thanks to all who answered.

-Mike
Yeah, what I meant was keeping your shutter speed constant, slipped my mind that 1/48th was slower than 60fps - I'd said earlier that you're limited by your frame rate as to the slowest speed you can use!
Steve
Steve Phillipps is offline   Reply With Quote
Old May 17th, 2009, 10:32 AM   #8
Major Player
 
Join Date: Nov 2008
Location: Santa Monica, CA
Posts: 318
cool. thanks steve.
Michael B. McGee is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Sony XAVC / XDCAM / NXCAM / AVCHD / HDV / DV Camera Systems > Sony XDCAM EX Pro Handhelds

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 11:43 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network