D300 built-in flash, Part 1: Blinding speed

Started Dec 25, 2008 | Discussions thread
David314 Veteran Member • Posts: 4,790
Re: Detector Range

Marianne Oelund wrote:

Thanks for sharing your results, which are a nice addition to the
information on this thread.

David314 wrote:

no it wasn't clipped by the measurement - it was turned off by the
flash unit

Clipping refers to the vertical axis, i.e., the signal amplitude.
Any real-world device has an amplitude limit, and clipping results
when a signal attempts to exceed that limit. The amplitude limit of
your detector is 1.6V, and if a signal approaches that level, it
won't be represented accurately.

regardless of the input and distance, this light sensor tends to show a flatter top than i have been seeing from other scope traces i have seen on the web

in this particular trace i was intent on capturing the duration of the pulse and this device seemed to have a minimum threshold affect so i had to pick my poison so to speak because of a limited dynamic range i suppose

there also maybe an adjustment in the light response curve hard to tell

i do know when it truly saturates, it flat lines and makes a perfectly smooth line

again, this is not a photo diode, but a light sensor with an analog output

at any rate, i think what is of most interest is the duration of the flash and you have shown once again very nicely in your original post the various flash lengths

my 'friend' Kluso seems to think that full power flash on the SB800 is only 1/1000 in duration

I am glad to see yet another scope trace confirming that the pulse is much longer in duration and behaves as a decaying exponential

good shooting


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