> From: Tony Ashton
> Subject: [Birding-Aus] Re: Seeing things
>
> Gidday all,
>
> Puzzle for people found with binoculars or cameras glued to
> their eyes. Tyto Wetlands is next door to Ingham airstrip.
> Medium-big helicopter took off as I was watching Black Kites.
> Casually looked through 10x32 Gerbers (as you do) as chopper
> sped across sky. Main rotor blades stood out sharply, in
> rotation. Focussed digital Panasonic FZ30 camera (not DSLR,
> no live preview; lens set at 700mm=) on chopper, and the
> blades came almost to halt. Back to binos: blades turning.
> Back to camera: blades near halt. Seems sighting through
> camera viewfinder accentuated stroboscopic effect.
The stroboscopic effect depends on the sampling frequency or
refresh rate of the display (or the flash frequency of the
strobe light). Different rate = different effect.
David
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