What's up with the drumsticks?

cletuscletus Registered Users Posts: 1,930 Major grins
edited June 17, 2013 in The Big Picture
Snapped a few pictures at the JD McPherson show last Friday (if you don't know who JD McPherson is, stop reading this, go to your favorite on-line music vendor and buy a copy of Signs and Signifiers - I'll wait for you). I noticed something odd about one of my shots of drummer Jason Smay:

20130615_0031-L.jpg


Take a look at the drumsticks:
i-DqJFCjb-L.jpg

It sure looks to me like a stroboscopic effect. The shutter speed was 1/20s and I count about forty copies of the drumsticks. That works out to something in the neighborhood of 800Hz. My guess is that at least some of the lighting is controlled by a switching power supply that doesn't bother with smoothing the power going to the lights. I guess it could be some kind of interaction between the slow shutter speed, low light, fast action and the CCD, but I've not heard of anything like that causing a strobe effect.

edit: It's probably a lighting system that controls levels via pulse width modulation.
Thoughts?

Comments

  • ziggy53ziggy53 Super Moderators Posts: 23,764 moderator
    edited June 17, 2013
    Yes, this looks like an effect caused by lighting powered by a faster frequency than line voltage, half-cycle AC power source (so missing a half-cycle). Beyond that, it's pretty difficult to determine exactly what system they might be using.

    Perhaps contact and ask them?

    http://www.jdmcpherson.com/contact.html
    ziggy53
    Moderator of the Cameras and Accessories forums
  • cletuscletus Registered Users Posts: 1,930 Major grins
    edited June 17, 2013
    ziggy53 wrote: »
    Yes, this looks like an effect caused by lighting powered by a faster frequency than line voltage, half-cycle AC power source (so missing a half-cycle). Beyond that, it's pretty difficult to determine exactly what system they might be using.

    Perhaps contact and ask them?

    http://www.jdmcpherson.com/contact.html

    Thanks Ziggy. I thought about this some more today and I'm 99% positive the at least some of the lighting was LED based, and thus would use PWM for level control. I might contact the venue and see if I can learn more about their setup (JD and the gang don't travel with lighting equipment... they just use what the venue provides)
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