[ARSCLIST] Fwd: Re: [ARSCLIST] Nikon sonic boom

[Robert Hodge <rjhodge@xxxxxxx>]

>>> Robert Hodge 10/3/2006 4:29 PM >>>
A Thought... A strong  RF harmonic caused when the ignition transformer
fired the flash tube within the camera. These flash units operate with
3-400 volt capacitors in the firing circuit and a tesla transformer to
ignite the tube.  If the facility had wireless mikes and a  light
control system that were sensitive to that harmonic, I can see how that
could cause the difficulty.  What you heard was a transient spike caused
by the electronic flash. A spectrum anlalyser operating within the
operating parameters of the wireless system could probably throw some
light on it. ( No pun intended).
I've never experienced it myself.   
Obtuse, I know. But clues aren't abundant. 
Very tough call as to how to prevent it unless you get the camera
checked out to see if someting is out of tolerance that would otherwise
minimise the transient spike. It may never happen again. Have you been
in this facility before ?



Bob Hodge



Robert Hodge,
Senior Engineer
Belfer Audio Archive
Syracuse University
222 Waverly Ave .
Syracuse N.Y. 13244-2010

315-443- 7971
FAX-315-443-4866

>>> Marcia Segal <joule@xxxxxxxxxxxxx> 10/3/2006 3:30 PM >>>
I'm posting this on behalf of a colleague not on the list; please
excuse cross-postings.

While it reads like a joke, and some people have suggested it as such,
it isn't, and any insights on what happened and how to avoid it would be
appreciated.

Sincerely,
Marcia Segal
American Folklife Center
Library of Congress
========================
Last Saturday eve., while presenting a Kevin Burke concert at a WA
State Park, I was taking pictures with my Nikon D-70 digital SLR. Most
of them I took with available light. At the end of the concert, I turned
on the built-in flash. When I pushed the shutter button, the sound
system, which was a professional sound system brought in by a
professional sound person, made a loud noise like a sonic boom & dimmed
the house lights momentarily, much to the distress of the audience.
Because I could not believe that it was caused by me, I took another
picture & it happened again, again to the audience's distress. After the
concert I tried it again & sure enough, my flash was the cause of it.
Has anyone else ever had a similar experience or does anyone know
anything about this? I've never had it happen & I've taken hundreds of
digital flash pictures at concerts. The sound person, who has almost 30
years in the biz, had never seen or heard anything like it. Anybody ever
have a similar experience? If yes, any thoughts on it?