D300 Flash sync speed


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Deluen

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May 31, 2008
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#1
This may be a dumb question. But how come when using the built in flash my sync speed is limited to 1/320, but with a sb-600 i have no limit on the shutter speed?
 

Rashkae

Senior Member
Nov 28, 2005
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#2
Because they have different specs. Read your manual.
 

Deluen

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May 31, 2008
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#3
...Well duh. I'm asking why

As i understand it sync speed is limited by the movement of the shutter planes across the sensor. At higher shutter speeds only a fraction of the sensor is exposed at the instant of flash and thus you would get a band of light over the area exposed when the flash fired.

Since this is a property of the camera body why would putting a different light change this?
 

catchlights

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Staff member
Sep 27, 2004
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#5
...Well duh. I'm asking why

As i understand it sync speed is limited by the movement of the shutter planes across the sensor. At higher shutter speeds only a fraction of the sensor is exposed at the instant of flash and thus you would get a band of light over the area exposed when the flash fired.

Since this is a property of the camera body why would putting a different light change this?
Read your D300 user's Manual, page 289.
 

Daedalus Trent

Senior Member
Apr 15, 2008
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#6
just curious. why is there no max sync speed when the sb600 is used? i thought its at 1/250?
Because with the SB600, the shutter and the flash are somehow able to synchronise at higher speeds?

P.S- there is a maximum speed, its the camera's maximum shutterspeed :)
 

grantyale

Senior Member
Oct 4, 2004
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#7
This may be a dumb question. But how come when using the built in flash my sync speed is limited to 1/320, but with a sb-600 i have no limit on the shutter speed?
Some flash power is lost to achieve this "limitless" syncing. At shutter speeds higher than 1/320, the second curtain starts to close before the first curtain is fully opened. Therefore, only a slit of the sensor is exposed at any time instance. SB-600 gives out many short pulses to make sure that everywhere on the sensor is equally lit, instead of a single strong pulse when shutter speed is below 1/320. The built-in flash simply doesn't have enough power to lose to perform a focal plane flash (FP-flash).
 

Deluen

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May 31, 2008
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#11
Some flash power is lost to achieve this "limitless" syncing. At shutter speeds higher than 1/320, the second curtain starts to close before the first curtain is fully opened. Therefore, only a slit of the sensor is exposed at any time instance. SB-600 gives out many short pulses to make sure that everywhere on the sensor is equally lit, instead of a single strong pulse when shutter speed is below 1/320. The built-in flash simply doesn't have enough power to lose to perform a focal plane flash (FP-flash).
Ah okay, that makes much more sense. Thanks =)
 

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