Appendix B. Flash Accessories
This appendix describes accessories that modify the light output of a flash unit in a variety of ways. Accessories and brackets for mounting flash units are described on another page.
Some accessories for the Vivitar 283 and other flash units are described below. These aren't essential for high-speed photography, but they can be helpful. Some of the Vivitar accessories may no longer be in production, but may still be available from photo store inventories. Look for accessories in used camera stores. They can be much cheaper that way.
A: This is a varipower module (VP-1) for a Vivitar 283. The module takes the place of the auto-thyristor module on the front of the flash unit. By turning a dial, one can select the fractional flash power. This provides some control over flash duration. The module is actually just a variable resistor. See Activity 2 for other ways to achieve the same function. If you use the VP-1, you'll find the following information helpful.
B: This is simply a 3-way flash junction. It allows one to discharge two flash units simultaneously from the same trigger source. This can be helpful if you need to boost light output. Another method of boosting output is described in D.
C: This light sensor extension cord (SC-1) plugs into the auto-thyristor socket on a Vivitar 283. The auto-thyristor module is then plugged into the housing shown here. In use, the housing is mounted on the camera's hot shoe and the flash is placed somewhere off camera. This allows the auto-exposure circuitry of the flash unit to calculate the exposure correctly when the camera and flash are not at the same distance from the subject. This situation is quite common in high-speed photography. One caution, though: When mounting the housing on the camera's hot shoe, first insulate the contacts with electrical tape. This prevents the camera shutter from triggering the flash unit. For high-speed photography, one wants a remote trigger to initiate the flash discharge.
D: A means of boosting the intensity from a Vivitar flash unit is shown in the photo below. A specially-constructed Fresnel lens focuses the light from the flash unit onto the subject. (While this increases intensity, it decreases beam spread.) These lens are available in a kit of 4 (simply called the Lens Kit, LK-1) including telephoto, extra telephoto, wide angle, and extra wide angle. In order to mount the filters, a Lens/Filter Adapter is also needed. A kit of colored filters (FK-1) is also available.