Saturday, 27 September 2008

HSS hack update

I posted and article called Sync speed and flash duration earlier this year describing a hack to enable cameras with mechanical shutter to shoot using a flash at shutter speeds over the cameras max sync speed WITHOUT using a proprietary flash system. Since then a little more info has become available so I thought I'd write another article focusing on how to do it rather than just investigating what it is. If you want more info on mechanical shutter and why it works then have a reader of the other article here.

So what do you need?
  • Camera
  • a proprietary flash that can do HSS/FP
  • A flash with manual settings
  • An optical slave
  • Optional: Radio trigger and a way to attach the optical slave to radio trigger

If you are using a Nikon camera with PC port I believe you can do this without the optical slave and connect either the flash or a radio trigger directly to your cameras PC port.

Ok now to put it together . . .

  1. Put the proprietary flash on the camera and select HSS/FP mode (this is the trigger so reduce power and point away from subject if you don't want to use as a light source)

  2. Select full power on the manual flash

  3. Put the optical slave where the on camera flash will trigger it

  4. Then the manual flash can be connected by a number of different methods, either directly to the slave, with a PC cord or a radio trigger can fill this gap, i.e. the transmitter can be attached to the optical slave and the receiver to the flash.

And . . . Ta Daaaa, you have a system that should give you HSS using a camera with a mechanical or focal plane shutter. You still need to remember that we are now using the flash as a continuous light source rather than an instantaneous flash, therefore shutter speed will now affect the exposure of the flash. Because the "continuous light source is not on for long and varies in power you will also see some light drop off across the frame, particular as the shutter speed gets higher. This also means that you will not get the large relative "gain" in power you can when you have a camera with an electronic shutter but it is another technique to keep in the back of your mind that might be useful one day.


Wedding Photographer French Riviera said...

Excellent. As a wedding photographer I really need the AF assist at night time but also the remote triggering capabilities of radio triggers. I will try this method to accomplish both (AF assist with the 580ex II, connected to RF-602 thru optical trigger)

thanks for your post!


Will Hore-Lacy said...

Hi Blaise,

Thanks for your comment!

A couple of things to consider:

1. Does your camera have a pc-sync port? If you don't need to use this hack to get high speed synch then it might be better if you could connect your directly to the camera this way.

2. Have you tried radio poppers? If you already have canon speed lights but want the radio interface then these are meant to be great to enable HSS and TTL, though they are $$$.

I haven't ever tried this set-up for normal triggering (i.e. not HSS), it should work but ironically, you may end up haveing to use a lower sync speed. Let me know how you go. Good luck!