D300 built-in flash, Part 1: Blinding speed

Started Dec 25, 2008 | Discussions thread
OP Marianne Oelund Veteran Member • Posts: 7,753
Timing measurements

David314 wrote:

i just read how you used a D3 to capture these images using flashes
to measure the relative timing?

Yes, the timing is the delay between the D300's flash trigger pulse, and the SB800 pulse peak which provided the light for the photo. The measurements were consistent down to 10-20us; photos with the same timing also showed the same shutter curtain positions, so I have high confidence in the results.

Did you try using the sync output? just put a pull up on it and you
would see the start stop pulse

I used this for the D3 shutter series back in September. For that setup, I didn't use optodetectors at all - just the PC terminal and a magnetic pickup coil on top of the flash that was illuminating the subject. Either approach is equally convenient; I used the optical sensors this time, because they were already set up for the pulse measurements.

also, it would be nice to see the flash in the shutter image - i
assume that was cropped out?

The photos were taken with a macro lens at high magnification, and light from the D300's flash wasn't visible. The thumbnails I posted were downsampled 6:1, so the originals are much larger (which explains the shallow DOF - only the shutter curtains are in good focus).

Although it would have been interesting to see, showing the flash light vs shutter position in the photos would have required firing it at high power every time. Since I took over 160 frames for the test, I didn't want to subject it to such heavy use and heating.

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MOD TOF guy
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