Film Friday Weekend: Shutter Speed vs Flash Sync Speed

by | Jan 29, 2022

Today’s Post by Joe Farace

A camera’s flash synchronizes with its shutter so that light passes through to the film or image sensor.

Cameras with mechanical shutters use an electrical contact within the shutter, which closes the circuit at the appropriate moment in the opening process. Some people just call it “flash sync”and, as I it’s different for every camera and that’s the critical part. As someone who shot part of a job, back in the film days, using a Hasselblad with a blown sync switch (and didn’t know it) this failure can producs no photos.

The shutter speed must be set at or below your camera’s maximum sync speed in order for the firing of an electronic flash to coincide with the shutter opening and allowing light to strike the sensor (or film,) If it’s set faster, only the ambient light—not the flash—will be captured by the image and in low light, like the ambient light that’s found in my former home studio for instance, you may only see part of the photograph that was exposed by the flash.

How I made the above portrait: I shot this  portrait of Kristen in my former home studio with a Pentax 6×7 and 75 f/4.5 SMC lens. The dark background in the above portrait somewhat hides this faux pas but what you see at the bottom of the frame is not vignetting. The flash exposure was 1/60 sec at f/11 but clearly I needed to shoot it at the 6×7’s correct sync speed of 1/30 sec, which I didn’t discover after the film was processed, something that would never happen with digital capture—because you would immediately see the problem. Nevertheless, the large negative and fine grain of Kodak’s Ektar 100 roll film allowed more than acceptable images and prints to be made. There’s no doubt Kodak Ektar 100 with its super color saturation and microscopic grain make for a formidable combination.

If you would like to send me a roll of film to review or any other stuff that could be used for these posts and my videos you can mail it to: Joe Farace, PO BOX 2081, PARKER, CO 80134


My book Joe Farace’s Glamour Photography is full of tips and techniques for using the cameras and lenses in my gear closet to produce glamour and portrait photography. New copies of the book are available from Amazon for $31.28, with used copies selling for the low price around nine bucks, as I write this, which is a bargain just based on its 125 pages of useful information. The Kindle version is $19.99 for those preferring a digital format.