Optical and wireless synchronization

Optical slave sync trigger – This is a type of flash synchronization that, as the name implies, is considered to be an extension of the main flash. It’s commonly known as the slave unit (photo 1). It is triggered either by the camera body’s built-in flash, a hot shoe mounted external flash or another strobe attached to the camera body via a synchro cord. I prefer to call it a triggering-device accessory. It receives the firing signal through its light-sensitive sensor. When the main flash fires, the flash attached to this device is fired in perfect sync with the main flash. The Slave Unit is primarily used in Multiple Flash Photography.

Wireless multiple flash – This new innovation of modern cameras allow for a wireless synchronization of multiple dedicated electronic flash system. It employs infrared light technology (Photo 2). A series of Canon DSLR cameras offers this menu as Wireless E-TTL. It can set up a number of their dedicated Speedlite flash units and trigger them remotely using the infrared light pulses. (We will discuss this in detail in the coming issues).

Synchronization via Radio Frequency – This advanced method of synchronizing multiple flashes has superior advantage over the other methods discussed above. It does not suffer the limited range and line-of-sight restrictions imposed by wireless E-TTL and Optical slave triggers. A number of companies manufacture radio remote systems. Among them are Quantum Radio Slave and the Bowens Pulsar. These third-party devices are relatively long-range and can be used in conjunction with optical slave units if necessary. (More about this in coming issue)

Last issue, we cited a problem of low speed X-sync and the ghost-like image it captures in situations where light is bright enough to damn your flash but inadequate or not ideal for shooting with available light.

To recall in part the problem of last issue and now the solution:

The X-sync of the 3D camera has flash sync of only 1/60th sec. which is typically slow by today’s standard. This low sync speed coupled with the automatic flash mode (non- TTL) lens opening of f5.6, will allow both the ambient light and the illumination from electronic flash to be captured in film. Thus, the moving subject registered with ambient light will be seen as ghost image being super-imposed by the image taken with the flash in the photograph. And in spite of that flash image is sharp, moving subject such as in recessional or bridal march would look blurred which is particularly more pronounced when photo is blown-up.

The churches mentioned (Ermita Church, Malate, and Sanctuario de San Jose, Greenhills) are typical examples of critical shooting grounds for users of slow X-sync speed cameras. At about 2 to 4 pm, the strong radiation of multi-colored light from large stained glass, surround ing and decorating the walls, dominates the ambient light in the church interiors.

This mix-colored light becomes so strong in bright sunny days that you can shoot comfortably without flash at ISO 100 film. But your big problem is the murky color of light that obliterates the color of one’s clothing and is particularly bad to human skin tones. Not only that, moving subjects taken with a flash at low speed X-sync exhibit a ghost image in the photograph.

The simplest solution to this problem is to use high speed sync, say – 1/125thsec or higher if available in your camera. But in the above case (where X-sync is only 60th/sec), here are some techniques to overcome the problem:

•Find for the exposure reading of the ambient light. (in this case it is f4 at 60th/sec).

•Change the usual setting of auto flash opening

(non-TTL) and camera from f5.6 to f8.

The effect of reducing the lens opening (from f5.6 to f8) reduce image exposure for available light down to two stop under, while flash is maintained at correct exposure. Note that this technique is practically similar to the case of X-sync speed pushed higher to 125th/sec. with latest model cameras.