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ihasa · 02-14-2012, 06:44 AM - **1 Like**

The sync speed is not the same as the actual duration of the flash burst itself (which is much much much shorter!)

falconeye · 02-14-2012, 06:44 AM - **1 Like**

Originally posted by Tycn

How does the use of flash allow shutter blur to be eliminated? The max sync speed seems to be well within the region of extraneous blur

True, the sensor (or camera body) moves during or between the runs of the shutter curtains, so it most likely happens while the flash exposure is done.

However, most of the time of the 1/180s sync time, the sensor will remain dark (if flash is the dominant light source) and is illuminated for a fraction of time only, like 1/10,000s, when both curtains happen to rest at their opposite ends. It simply takes 1/180s to open and close the curtains. The flash is much shorter. So short, that no visible sensor/body movement remains.

Tycn · 02-14-2012, 06:53 AM

Oh. I had never thought of it that way. Thanks!

philbaum · 02-14-2012, 10:16 AM

Originally posted by falconeye

True, the sensor (or camera body) moves during or between the runs of the shutter curtains, so it most likely happens while the flash exposure is done.

However, most of the time of the 1/180s sync time, the sensor will remain dark (if flash is the dominant light source) and is illuminated for a fraction of time only, like 1/10,000s, when both curtains happen to rest at their opposite ends. It simply takes 1/180s to open and close the curtains. The flash is much shorter. So short, that no visible sensor/body movement remains.

This site here: Yongnuo Speedlite YN 460-II Flash Review (Manual Flash) | Speedlights.net

has done some flash duration testing using the 10% power on and off duration methods vice the 50% on and off method reported by many manufacturers. Using the 10% rule, flash durations at full power range from 1/230 for a newer Nikon flash to 1/285 for a newer Canon flash. However, when power drops to 1/2 or smaller, durations drop down to 1/1000 to 1/20,000s for all flashes.

just for info.

falconeye · 02-14-2012, 03:55 PM

Thanks.

IMHO, the flash question is now answered and was OT in this thread and it was resurrected w/o a strong need.

Therefore, may I kindly ask to refrain from doing further postings and let the thread sleep again until something significant happens which is related to the topic? My sincere thanks.

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02-14-2012, 06:44 AM - 1 Like	#151
ihasa Veteran Member Join Date: Jul 2009 Location: West Midlands Photos: Gallery Posts: 2,066	The sync speed is not the same as the actual duration of the flash burst itself (which is much much much shorter!)

02-14-2012, 06:44 AM - 1 Like	#152
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871 Original Poster	Originally posted by Tycn How does the use of flash allow shutter blur to be eliminated? The max sync speed seems to be well within the region of extraneous blur True, the sensor (or camera body) moves during or between the runs of the shutter curtains, so it most likely happens while the flash exposure is done. However, most of the time of the 1/180s sync time, the sensor will remain dark (if flash is the dominant light source) and is illuminated for a fraction of time only, like 1/10,000s, when both curtains happen to rest at their opposite ends. It simply takes 1/180s to open and close the curtains. The flash is much shorter. So short, that no visible sensor/body movement remains.

02-14-2012, 06:53 AM	#153
Tycn Junior Member Join Date: Dec 2011 Location: Sydney Posts: 29	Oh. I had never thought of it that way. Thanks!

02-14-2012, 10:16 AM	#154
philbaum Veteran Member Join Date: Oct 2007 Location: Port Townsend, Washington State, USA Posts: 3,659	Originally posted by falconeye True, the sensor (or camera body) moves during or between the runs of the shutter curtains, so it most likely happens while the flash exposure is done. However, most of the time of the 1/180s sync time, the sensor will remain dark (if flash is the dominant light source) and is illuminated for a fraction of time only, like 1/10,000s, when both curtains happen to rest at their opposite ends. It simply takes 1/180s to open and close the curtains. The flash is much shorter. So short, that no visible sensor/body movement remains. This site here: Yongnuo Speedlite YN 460-II Flash Review (Manual Flash) \| Speedlights.net has done some flash duration testing using the 10% power on and off duration methods vice the 50% on and off method reported by many manufacturers. Using the 10% rule, flash durations at full power range from 1/230 for a newer Nikon flash to 1/285 for a newer Canon flash. However, when power drops to 1/2 or smaller, durations drop down to 1/1000 to 1/20,000s for all flashes. just for info.

02-14-2012, 03:55 PM	#155
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871 Original Poster	Thanks. IMHO, the flash question is now answered and was OT in this thread and it was resurrected w/o a strong need. Therefore, may I kindly ask to refrain from doing further postings and let the thread sleep again until something significant happens which is related to the topic? My sincere thanks.

LumoLabs: Shutter induced blur with the Pentax K-7 camera

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