Just Got your First Flash? Here’s What you Need to Know


Congratulations! You have just acquired your very first flash. Now comes the fun part: figuring out what all those buttons do in order to get the most out of your new speedlight.

Shutter Speed (Almost) Doesn’t Matter

One thing that will trip many flash beginners up is that shutter speed gets weird. If the flash is too strong, no amount of shutter speed adjustment is going to change how it appears in your final image. A flash will provide a burst of light that only lasts for a fraction of a second, somewhere in the realm of 1/1000 second or faster for most flashes. If your shutter speed is at 1/250 second or 1/50 second, both exposures will receive the full power of that flash. The speed with which flashes operate also explains how they can be used to freeze motion as the flash duration can be faster than the shutter speed.

Aperture is where you will need to go if you want the exposure to change without adjusting the power settings on the flash itself. This is because aperture actually limits how much light can enter the camera, so even though you are getting the full flash blast you can control how much of the blast is captured. This will impact all aspects of your exposure, not just the flash, so set up your aperture as you need it for a scene as a whole. Another option is to adjust the ISO.

Now, you can’t ignore shutter speed. Due to how focal-plane shutters work, you will generally only be able to use shutter speeds up to 1/250 second or slower, unless of course you have high-speed sync capabilities, but more on that later. Shutter speed will affect the amount of ambient light captured. Imagine you are shooting at night without a flash and the image comes out dark. Add a flash and your subject and foreground are perfectly exposed, but the background is still very dark. If you choose a slower shutter speed you may be able to brighten the background while keeping the exposure on your subject the same. This can be used for unique effects, such as light painting or combining long exposures with a sharp foreground subject.

A new technique to master is the use of flash with electronic shutters, which requires even more care than before. Sony managed it in certain modes on the a7R IV, but with sync speeds of 1/5 second or slower; the Sigma fp can do it at up to 1/30-second. It is especially important to note this when you start using your flash because of how ambient light will affect your images. The slower the speed, the more ambient light will be captured, which can be good and bad. It can help fill in a background that isn’t quite lit by your flash, but you may not want that.

Sony Alpha a7R IV Mirrorless Digital Camera

Guide Numbers, Output and Bounce

There’s a lot of numbers when it comes to flash. Let’s talk about power first. This is indicated by the guide number for shoe-mounted flashes. Simply put, bigger numbers are generally more powerful. Be wary, however, as zoom heads which focus the beam angle can inflate this number so one flash rated at 100’ at 35mm is actually more powerful than a flash rated at 100’ at 200mm. You will also see control numbers along the lines of 1/1 to 1/128, this is the power setting you have on the flash itself. Going from 1/1 to 1/2 indicates a change of a stop and so on to 1/4, 1/8, 1/16, etc. A wide range gives you more flexibility, though most modern flashes from the capable and affordable Bolt VD-410 to the high-end Profoto A1X Studio Light will give you plenty of functionality. If you want to dive more into this, I would highly recommend The B&H Speedlight Buyer’s Guide.

Bolt VD-410 Manual Flash

One thing you should know when it comes to power is that it doesn’t always make sense to adjust the power setting—moving closer or farther away from your subject, if possible, can help you make quick adjustments on the fly as power output decreases over distance. This is especially true if you decide to get your flash off camera via some sync cables or remote triggers. Again, more on these extra functions later. The most useful feature in speedlights are their bounce capabilities. The heads can be tilted and turned to point in nearly any direction, which gives you a lot of control over how the light interacts with your scene. The most common usage is to point the head upwards so that light bounces off the ceiling and provides a soft, even illumination. Combine this with a bounce card to push some light forward as a fill for the shadows and you are well on your way to creating nice flash images. You can apply this method to walls too, just point it to the left or right as needed.

Impact Sync Cord Male Mini (3.5mm) to Male PC

When you adjust the output the flash duration will change as well. Generally, the more powerful the setting, the slower the duration, meaning less of an ability to freeze motion. If you want to use this for fast-moving subjects, you will be better served with lower power settings as these will provide the fastest durations. Keeping the room dark for this type of work is recommended.

The Fun Stuff and Accessories

If you are fortunate enough to have a flash with some bonus features there are a few you should know about. First, let’s talk about TTL support. Generally, as speedlights are shoe-mounted and many feature direct compatibility for specific camera manufacturers, you can get some nice features added on. TTL is perhaps the most widely used as it combines the camera’s through-the-lens metering system with flash, giving you automatic exposure. This is helpful if you are just starting out with flash and want some decent results quick. It also works well with exposure compensation for on-the-fly adjustments. The next most important feature is high-speed sync, or HSS. Normally, as mentioned earlier, you will max out your shutter speed around 1/250 second when using flash. HSS solves this by syncing the flashes pulses to the movement of the shutter, opening the door for shutter speeds up to 1/8000 second, perfect for balancing bright outdoors with flash lighting.

Next up in modern features is wireless. Most flashes have some sort of remote slave function, though it can be as simple as an optical receiver that triggers when you fire another flash or as complex as a radio transceiver with multiple channels and groups you can individually configure with TTL support. Optical systems are fairly straightforward, and many brands have their own setups with pre-flashes for TTL communication. This only matters if you notice sync issues with your off-camera flash as you can usually choose between instant sync and skip pre-flash on your remote flash. If you are just learning now, I wouldn’t concern yourself too much with these, but it is nice to know your flash has them if you ever want to try out something new, especially since going off camera can dramatically change lighting possibilities.

On to accessories! When you want to master flash you will learn that modifiers are the way to go, especially with bigger monolights and heads. Speedlights have their own unique set of accessories available, and you can read about our five favorite modifiers here. For brand new flash, I would recommend starting out with bounce cards and gels. This gives you both a practical and more fun setup of affordable tools to get the most out of your first flash.

MagMod Standard Gel Set

If you are excited and maybe want something a bit more specialized, definitely go check out our other lighting articles on B&H Explora. There you can find a list of our recommended lighting kits, options for macro photography, adventure-ready equipment, and much more.

Do you have any specific questions about your flash? Want to figure out create a specific lighting effect and need some new tools? Make sure to leave a comment below!

1 Comment

One thing you don't mention when doing bounce flash is the color of the "bounce surface", that is, what your flash is bouncing *off of*.  If it's anything other than white, then the flash-light will pick up that color and your exposure will be have a color cast to it--which may or may not be what you are looking for--that it wouldn't have had had you either not bounced OR had a white colored bounce "surface".  Other than that, a helpful article.  Thanks!