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  • Robert S Bradshaw

Flash Photography: The Multi Flash function w/Hertz and Times Explained

Updated: Mar 8

We pass by this function everyday when we set our flashes to manual, TTL, etc. However, you might just be passing by something that could blow your photographic mind. In conjunction with your dedicated transmitter, cool things are just a button away.

Multi-flash function in photography, utilizing hertz, involves the ability of a flash unit to emit multiple flashes per second. Hertz (Hz) is a unit of frequency that measures the number of cycles or events per second. In the context of flash photography, hertz indicates how rapidly the flash unit can fire flashes.

When using the multi-flash function with hertz settings, photographers can control the frequency or rate at which the flash fires during a given time frame. This capability enables them to create various lighting effects, freeze motion, or capture multiple instances of action within a single exposure.

For example, setting the flash unit to a higher hertz value allows for more rapid firing of flashes, which can be useful for freezing fast-moving subjects or creating a series of evenly spaced light bursts. On the other hand, lower hertz settings result in a slower flash rate, which may be preferable for achieving less exposures on a single frame or capture.

Photographers can experiment with different hertz settings to achieve their desired creative vision, whether it involves capturing dynamic action shots, creating unique light patterns, or controlling the ambient light in a scene. Understanding and utilizing the multi-flash function with hertz in photography opens up a range of possibilities for creating visually stunning images.

Understanding Hertz vs. Times

When it comes to multi-flash photography, you might come across terms like "hertz" and "times." Let's clear up what these mean:

  • Hertz (Hz): This refers to the frequency of flashes emitted by the flash unit per second. For example, if a flash unit has a frequency of 5Hz, it means it can produce 5 flashes per second.

  • Times: This refers to the number of times the flash fires during a single exposure. So if you set your flash to fire 5 times during a single exposure, it will emit 5 flashes.

Example: Let's say you would like to shoot 4Hz. Simply put, that is 4 flash events per second. If you set the times to 4 that is a 1 sec exposure to capture the 4 flashes. If set to 8 times, that is a 2 second exposure. Remember, Hz is events(cycles) per second. You get the picture now. Now you can set the hertz to some pretty astonishing amounts. For instance, I can set my strobe to 150Hz. That is a 150 flash cycles in a second. Pretty amazing! Of course, the flash defaults to a very low power to accommodate your desired need (ie: 1/128th power).

Here is where it gets mathematically awesome. It should make sense by now (maybe :) that 4Hz vs 150Hz is a much different frequency within that second. Let's say that you like how fast the cycles are at 150Hz but don't want the flash to complete a 1 second cycle by setting the times to 150. Just set the flash to the number of times that you would like the flash to fire. Let's say you want 10 of the 150Hz. Set your times to 10. Now you will get 10 flashes at the speed of the 150Hz. Pretty impressive, right. Your mathematically correct shutter speed is a simplified fraction of the times under the hertz. So, in this instance, 10 times/150Hz. This simplified, is 1/15th of a second.

The discussion above is mathematically exact in a dark environment where the flash is properly exposing the desired subject (above: people). Ideally, that subject is moving by the way. Here is where it can get even more FUN. You can introduce ambient light during the exposure (above: paper airplane). At your discretion, you can drag (prolong) the exposure (shutter speed) to allow the constant light to record to the sensor along with the flashes stopping action. This makes for some very unique and visually stunning light trails. Happy Shooting!

I hope this helps to make the 'multi-flash' mode a little more approachable. If any reader sees information that could be clarified, please let me know. Forgive any type-o's. This wasn't written in ChatGPT.

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