Flash Extender User Guide

The Flash Extender is a compact and lightweight accessory that will boost your flash output by 2-3 f-stops for telephoto flash photography. When used with TTL (Through-The-Lens) flash metering, exposure is automatically handled by your camera and flash, and no special compensation is required.

The Flash Extender concentrates your flash output into the area covered by a 300 mm or longer lens (as viewed with 35 mm film coverage; adjust accordingly for your digital camera or other film formats). The light that would normally be wasted is focused back into your frame, allowing your flash to reach distant subjects and boosting its power.

Some tips for best results:

  • With TTL (Through-The-Lens) flash metering your camera and flash will automatically compensate for the increased light output from the Flash Extender. You don't need to add additional compensation on your camera or flash to account for the Flash Extender.
  • The LCD display on the back of some flash units that indicates the minimum and maximum distances for flash exposures will not reflect the extra reach that the Flash Extender gives you—the flash doesn't "know" that the Flash Extender is attached. Your TTL system, however, will automatically adjust and give you the correct exposure. See How far will my Flash Extender reach?
  • Fill flash, to fill in shadows or backlit subjects, typically looks best when set at about –1.5 to –1.7 f-stops. More than this may look “over-flashed.” Experiment with your system to find the best settings.
  • The Flash Extender support arms are bent at an angle at the flash head. For best results, you should line up this bend with the front lens of your flash unit. Doing so will hold the Flash Extender Fresnel lens the proper distance from the flash head.

  • The output is best for most flash units when the flash head is manually zoomed to about 35-50 mm.
  • Scratches or dirt on the Fresnel lens will degrade performance. Store the lens in its protective pouch when not in use. The Fresnel Lens is flexible, but it will crack if bent too far. (Replacement lenses and other parts are available from our Online Store.)

We recommend the use of a flash arm (flash bracket) and off-camera shoe cord with the Flash Extender. With the right flash bracket you can

  • mount the flash higher to minimize red eye and eliminate any shadows from your lens hood
  • maintain the flash in an upright position even when you rotate lenses with tripod collars to vertical
  • precisely tilt the flash up or down slightly, to better aim the flash for near or far subjects
  • obtain better balance when using large telephoto lenses

Our favorite flash arms are from Really Right Stuff.

With lenses shorter than 300 mm, especially wide angle, you will get a “hot spot” in the center of the image (which might work in certain images). You can preview this coverage by (a) manually firing the flash and observing where the light hits, or (b) taking a test image and viewing the results.

Caution: The Fresnel lens acts like a magnifying glass. Don’t point it directly towards the sun, because the focused rays can cause flammable materials to ignite, burn your skin, or melt and deform the plastic on your flash unit.

Instructions for attaching the Flash Extender