fbpixel

Moderators: E.J. Peiker, Greg Downing

All times are UTC - 5 hours

  
« Previous topic | Next topic »  
Reply to topic  
 First unread post  | 6 posts | 
by WDCarrier on Mon Jan 09, 2017 10:53 pm
User avatar
WDCarrier
Forum Contributor
Posts: 1089
Joined: 15 Mar 2012
Location: Paradise, California
Can someone explain to me why, with the setting on AV, the focus on spot with the camera mounted on a tripod and the subject is stationary so that all frames look identical in composition, in a high speed burst of 6 shots #s 1,2,5 and 6 are at 1/200 and 3 and 4 are at 160 (and overexposed).  Is this a lens or camera issue? 
[font=Helvetica, sans-serif]“Our lives begin to end the day we become silent about things that matter.” MLK[/font]
 

by Kim on Tue Jan 10, 2017 1:36 am
Kim
Forum Contributor
Posts: 402
Joined: 23 Dec 2005
Location: Victoria, Australia
Could it be that to get the number of frames per second the camera needs to compensate, as in, reduce the shutter speed to achieve the frames required?
 

by Vivek on Tue Jan 10, 2017 7:51 am
Vivek
Lifetime Member
Posts: 747
Joined: 05 Aug 2008
Location: Santa Clara, CA
Member #:01186
WDCarrier wrote:
Can someone explain to me why, with the setting on AV, the focus on spot with the camera mounted on a tripod and the subject is stationary so that all frames look identical in composition, in a high speed burst of 6 shots #s 1,2,5 and 6 are at 1/200 and 3 and 4 are at 160 (and overexposed).  Is this a lens or camera issue? 


This is interesting. The "spot" is really not a "spot" but a small area. If the area covers dark and light object or an edge, this could happen. Can you please share a photo of what you are shooting exactly with the focus point highlighted?
-- Vivek Khanzode
http://www.birdpixel.com
 

by Vivek on Tue Jan 10, 2017 7:54 am
Vivek
Lifetime Member
Posts: 747
Joined: 05 Aug 2008
Location: Santa Clara, CA
Member #:01186
Kim wrote:
Could it be that to get the number of frames per second the camera needs to compensate, as in, reduce the shutter speed to achieve the frames required?


This is not the case. The shutter speed would have to *increase* if the frame rate is in question. Say 7D2 is capable of 10fps. It means that each frame has 100ms or 1/10th of a second. The current shutter speed is 1/240 or much higher. Even if we included the mirror travel time etc., your suggestion would not make sense.
-- Vivek Khanzode
http://www.birdpixel.com
 

by rajandesai on Tue Jan 10, 2017 9:47 am
User avatar
rajandesai
Forum Contributor
Posts: 1937
Joined: 06 Apr 2009
Location: Westford, MA
Member #:01263
You mentioned Av - so I assuming Canon. I always assumed that when shutter is half pressed, exposure is locked and wouldn't change during high speed burst.
I typically shoot in manual (or use the exposure hold when using Av) so I haven't noticed this behavior. May be it is worth experimenting with my cameras too.
 

by WDCarrier on Tue Jan 10, 2017 10:58 am
User avatar
WDCarrier
Forum Contributor
Posts: 1089
Joined: 15 Mar 2012
Location: Paradise, California
rajandesai wrote:
You mentioned Av - so I assuming Canon. I always assumed that when shutter is half pressed, exposure is locked and wouldn't change during high speed burst.
I typically shoot in manual (or use the exposure hold when using Av) so I haven't noticed this behavior. May be it is worth experimenting with my cameras too.



The body is a7DII, the lens a 500mm f4, shooting in silent mode.  I use backbutton focusing so the shutter button doesn't affect the focusing.
[font=Helvetica, sans-serif]“Our lives begin to end the day we become silent about things that matter.” MLK[/font]
 

Display posts from previous:  Sort by:  
6 posts | 
  

Powered by phpBB® Forum Software © phpBB Group