Flash Compendium

Other Flash Systems

Studio Flashes

Some Minolta and Sony camera bodies feature a PC-sync socket. It is used to trigger larger studio flashes. These flashes are typically very powerful, are powered via power lines instead of batteries, have a modeling light, and their output can be adjusted. They are, however, not TTL capable. This means that the camera can only trigger these flashes but can not stop flash output. You have to use these flashes in manual mode. You have to use a lot of calculations or an external flash exposure meter to calibrate the flashes.

The Minolta PCT-100 and Sony FA-ST1AM provide a studio flash socket for cameras that do no have one built-in.

This is a more powerful but less comfortable system. But when you use these flashes you (hopefully) know what you're doing.

Slave Flashes

These are either small battery-powered flashes or large studio flashes which are triggered by a pulse of light. The idea is that when the main flash on the camera fires it also triggers the slave flashes. Again, this is a non-TTL system. These flashes can only be triggered, but not stopped by the camera. You have to adjust the output from these flashes manually.

You have to be careful to not use wireless flash or pre-flash metering with the main flash. Otherwise the control pulses or metering flashes trigger the slave flashes, but the shutter is not yet open at this time. You're in trouble when you use a digital camera, because these always either use pre-flash metering or ADI with pre-flash metering for automated flash. You have to switch the flash to manual mode to avoid the pre-flash. Again, if you use such a system you have to know what you're doing.

Triggering slave flashes with the built-in flash

Here's a tip how to trigger slave flashes with the built-in flash, without causing exposure from the built-in flash:
Most of the simpler wireless triggers for studio flash systems can't be used on Minolta cameras. They either have the wrong flash foot, or they are not triggered by the camera because the camera doesn't recognize the trigger as a flash unit. At the same time, if you use the built-in flash as the trigger, the camera tries to expose the subject with the built-in flash. Here's how to avoid this:
Set the ISO value of the camera to the highest possible value. This will make the camera think you have a very sensitive film loaded that needs only a small flash burst for proper exposure. Of course, changing the ISO value will not change the actual sensitivity of the film. With unchanged exposure settings (use M mode!) and unchanged studio flash settings, you will get the required exposure. The small burst from the built-in flash will be hardly visible in the picture, but will be enough to trigger the studio flash.
Of course, this trick will not work with digital cameras. With these, changing the ISO setting will also change the actual sensitivity of the sensor. It will also not work with pre-flash metering systems. With these, the metering flash instead of the main flash would trigger the studio flash. So turn off ADI, wireless flash and HSS. Finally, it won't work with cameras that don't allow overriding the ISO setting or that don't have a non-pre-flash metering system (Dynax 40/Maxxum 50, Dynax/Maxxum 3).

Here's what you can try with the 7D or α700: In the camera's recording menu, set “flash mode” to “fill-flash”, “flash control” to “manual”, and set the power ratio to “1/16”. This does two things: Any pre-flash is turned off, and the intensity of the built-in flash is set to the lowest setting. Also set the ISO value to a low number, e.g. 100 or 200. Both together will result in little exposure from the built-in flash. Again, this small flash burst may be enough to trigger a studio flash system. Of course, with a digital camera you can see the effect of the built-in flash and of the studio flash immediately after the shot. If necessary, you can further reduce the intensity of the built-in flash with filters or a piece of paper.

Readers' comments

#1: Comment posted by Jacques on September 17th, 2009 - 02:07:50 PM:
Ive got the A700 and have the Sony HVL 58am flash and some older minolta flash. Ive bought a slave trigger advise with light sensor and it didnt work. After this review about trigger slaves with the A 700 I change my settings and it works perfect!Thanks this is the best site

#2: Comment posted by N3T on March 12th, 2014 - 02:04:32 AM:
Some flashes and adapters have got the possibility to switch between first flash or "ignore first ttl preflash" and fire on actual second main flash that exposes the scene, also known as S1 and S2 modes (that apply for non minolta optical slaves)