In the previous article, we talk about the importance of flashes in high-speed photography. We learned about why it’s difficult to shoot high-speed photos in natural light and why we need an artificial light source like flashes.
In this article let’s talk about what to look when you choose a good flash for high-speed flash photography work.
1. Flash Power: Power is the most important factor when buying a flash. It’s measured in guide numbers which is a standard way to define the power of a flash. A higher guide number means a more powerful flash. So always buy a flash with guide number 50 or above.
There are two reasons for buying a powerful flash, first we use lower ISO and narrow aperture so we required a lot of light and second and most importantly we always use flashes with low power setting like 1/64 or 1/128 and if your flash is low powered, it’ll produce very little light at these settings that will be not enough.
Why we use flash with low power because at low power, we get faster flash duration. With 1/128 power, we can get up to 1/35000 second of flash duration. Below is the chart that shows the flash duration at different power settings.
2. Manual Control: In high-speed photography, we always prefer manual control for power settings. A good flash is adjustable from full power to 1/128 power in 1/3 stops increments. It gives you the option to obtain correct exposure. You can also set different power settings in different flashes for some dramatic effects.
Some low-cost flashes give you the option to increase or decrease power only in one stop difference and you should avoid these flashes because you’ll have a problem controlling light for your shot.
3. Optical Slave Mode: This is the most important feature for high-speed photography flashes. In slave mode, flash detect the light of main flash and fire synchronously. It’s the same as controlling two or more flashes with radio trigger.
The benefits of slave mode are that you don’t need to connect multiple flashes with cables, it works with any brand of flashes so if you have flashes from a different company, they can work together.
4. Zoom Head: If you are shooting a small subject, zoom head is a very useful feature. You can control the flash coverage and focus the light beam to your subject only. When light is focused, you will require less flash power compare to wide coverage. Most flashes cover between 24mm to 200mm range.
5. Swivel and Tilt Head: When you are using flash with slave mode, this feature is very handy. Flashes with slave mode have an optical sensor at the front which detects light from the main flash and trigger itself. Sometimes when the main flash is on low power and slave flash sensor is in opposite direction, it finds difficult to sense light and fire. In this case, you can rotate the flash head to 180 degrees and bring the sensor toward the main flash.
6. Multi (Stroboscopic) Mode: In multi-mode, a series of flashes is fired in a specific time period and you can capture multiple actions in a single frame. This mode is helpful for creative work.
7. High-Speed Sync (HSS): Every camera has a flash sync speed which varies between 1/160 to 1/320 seconds. If you are using flash, you can’t go above your camera’s flash sync speed but with HSS you can use flash with any shutter speed even 1/8000 seconds. Sometimes you may face the situation where you need to go above sync speed to cut ambient light, in such case HSS will be your rescue.
8. LCD Display: LCD display helps you to control the power easily especially when you are using multiple flashes.
9. Flash Recycle Time: It’s absolutely necessary that recycle time of your flash is fast so you won’t miss any shot just because one of your flashes didn’t fire.
10. TTL Metering: TTL stands for through the lens and it’s the fastest and easiest method to use a flash. The camera does all the calculation according to the scene and communicates with the flash about how much power is required. It also matches the flash zoom with the actual focal length of the lens. This feature is not much use for high-speed photography but it’s very useful for other photography work.
About the Author
Ramakant Sharda is an author, iOS App publisher, passionate photographer and a MIOPS Ambassador based in the beautiful “Pink City” of India, known as Jaipur. His work has been published in various magazines, newspapers, and blogs. He has published three Coffee Table Books, he writes about photography and also teaches photography in his workshops. Check out his website http://ClickManic.com to see the masterpieces created by him or download his free app for iPhone and iPad “30 Days to an Ace Photographer“.