Thursday Vibes: Shutter Speed vs Flash Sync Speed

by | Dec 19, 2024


Back when I was getting started in professional photography, I asked my mentor what kind of mistakes to avoid when making portraits. I expected him to tell me about some kind of technical, mechanical problem but instead he cautioned me to always “talk to your subjects.” He should have also warned me about the dangers lurking with flash synchronization…


Today’s Post by Joe Farace

“Light makes photography. Embrace light. Admire it. Love it. But above all, know light. Know it for all you are worth, and you will know the key to photography.”George Eastman

Flash synchronization aka flash sync is defined as the method for synchronizing the firing of a flash with the opening of the shutter to admit light onto the photographic film or digital sensor.

Shutter SPEED ALSO MATTERS

Flash synchronization for cameras with mechanical shutters have an electrical contact within the shutter itself that closes the circuit at the appropriate moment in the (shutter) opening process. Some people just call this process “flash sync” and the shutter speed at which it operates is different for every camera. That’s the most critical part! As someone who, back in the film days, shot a wedding using a Hasselblad that, sometime during the event, had the sync switch fail (and didn’t know it) this failure produces no photos. As the old photographer’s joke goes: “Your wedding photos look great. There’s not a lot of’em.” Fortunately I had shot a lot of available light images. I had the camera repaired and quickly learned a way to check during a wedding to make sure the sync was working, so naturally it never happened again.

On the other hand….The camera’s 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 allow light to strike the sensor (or film,) If it’s set faster, only the ambient light—not the flash—will be all or partially captured by the image. In low light, like the ambient light found in the environment, such as the hotel room in the featured example, 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 Amy several years ago during a private model shoot in the hotel room of a magazine editor during a PMA trade show. The camera I brought to the show to make shots for an article I was going to write for Shutterbug was a Contax G1 with a 45mm f/2.0 Carl Zeiss Planar lens. I never thought I might be doing a model shoot with it.

This image was shot on film so there’s no EXIF data  to show that I shot it at 1/125 sec, when the flash sync for the Contax G1 was 1/100 sec or slower. I initially missed the RED “X” on the shutter speed dial but eventually figured that out and did make some nice image of Amy. Of course, all of the best ones were like the image shown, Some of the images I made are not possible to show on this blog but might appear in a future Password Protected post.


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 $34.95, although it is marked as “Temporarily of of stock.” However, used copies are selling for around ten bucks, as I write this and the Kindle version is $19.99 for those preferring a digital format.