Flash vs continuous light photography (which is better for portraits?)

We take light for granted …until we first pick up a camera. Then we realise just how important light is in photography and it starts to become confusing, because that’s when we learn about the different types of light – natural light vs flash and flash vs continuous light.

If you choose to use artificial lighting in photography, you’ll naturally start looking around for the best light to buy to help you take great photos. You’ll be confronted with a huge array of choices.

So let’s take a look at the two versions of artificial light so that you can decide which lighting system will suit your needs. Then you can start researching the actual lighting gear you might need.

You’ll find a handy infographic of flash vs a continuous light source at the end of this article.

What is the difference between flash and continuous lighting?

Both flash and continuous lighting are forms of artificial lighting, and can be modified to manipulate the light like when you put a lampshade on a bare bulb in your home for nicer light. Examples of light modifiers include softboxes and umbrellas.

Flash vs continuous light for portrait photography indoors

Plus, because both flash and continuous lighting allow you to light the subject in low light conditions you can use a lower ISO than shooting with just natural light, which leads to a better quality image.

Now let’s look at the differences…

Two types of strobes for flash lighting
These are both flashes – furthest away is a monoblock studio light and the closest is a speedlight. (I need to redo this shot, because the speedlight looks big, but is actually much smaller than the strobe light)

Flash / Strobe lighting

Flash photography is also referred to as strobe photography. So when referring to photography lighting that emits a very quick burst of light, you’ll see it referred to with both names – flash and strobes.

Speedlights are smaller, less powerful types of flash lighting that you can fit into the hotshoe of your camera for on camera flash, or use off camera. They’re also referred to as pocket flashes or flash guns. However, they’re not strobes.

Types of strobe lighting are:

  • Pack and head – mains powered studio lights with a separate power pack (plug the mains into the power pack and plug the power pack into the head), mount on a light stand
  • Monoblocks – the light and the power pack are in one unit (can be battery powered or mains powered), mount on a light stand
Falcon Eyes LED lighting with softbox and grid
LED light panel continuous light fitted with a softbox and grid

Continuous lighting

Continuous lighting (also called constant lighting) on the other hand, does exactly what it says on the tin – it emits light continuously. So, for example, your desk lamp is a form of continuous light.

Other types of continuous lighting include:

  • Street lighting
  • Tungsten light (house lights)
  • Torch light
  • Video lights
  • LED light panels
  • Fluorescent lights
  • Ring light
Portrait Lighting with flash vs continuous light LED panel
Lit with flash to camera left (fitted with a blue gel) and continuous light to camera right (adjusted to a warm color temperature for contrast)

Can you use continuous light with flash?

Continuous light works great with flash!

I often use this combination in the studio when I’m photographing in a blackout situation. I set the flash as my key light and then use the continuous light in different ways:

  • With a constant light source on, even as a rim light, my camera can focus better in the dark.
  • Plus, using continuous light as a fill light also prevents the subject’s pupils from becoming too large in low light.

Why do photographers use flash instead of continuous light?

Each type of artificial lighting has its advantages and disadvantages. What and where you photograph has a big impact on lighting kit choice. Because you can do so much more with flash, most professional photographers use flash more than continuous light.

But there’s a time and place for everything, as well as personal preference.

So, to help you to decide on a photography lighting kit that’s right for you, let’s look at the pros and cons of each.

Flashing lighting with umbrella modifier and diffuser
Studio lighting with large white reflective umbrella and on the right with diffuser fitted to the umbrella

ADVANTAGES of flash lighting

1. Power

The biggest advantage of flash vs continuous lighting is that it’s more powerful, so you can use it outdoors to light your subject and maintain a well exposed sky. No more white, washed out, blown out skies!

When your subject is positioned with their back to the sun, their face is in shadow. By adding in flash you can light their face and bring life to their eyes with the catchlights created by the flash.

2. Overpower natural light

You can even manipulate the appearance of natural light in photos by making it appear darker than it is with off camera flash. In golden hour this makes the colors in the sky even more saturated.

Powerful strobes are so powerful in fact that you can actually create a completely black background in outdoor photos. To do this you’d also need to set a high shutter speed.

The maximum amount of light that a flash emits depends on the flash itself. Although monoblocks (also referred to as studio lights) are more powerful than speedlights, their power varies. For example my…

  • Profoto B1X is 500 watts,
  • and is more powerful than my B10X, which is 250 watts

It’s just like deciding on which bulb to buy for your house lights – you look at the wattage and buy according to your needs.

Some brands are more powerful than others, with the more expensive ones usually being the better quality, higher powered options.

3. Freeze motion

You can adjust the amount of light emitted by the flash to ensure that you have enough light not only to light your subject, but even to overpower the ambient light and to freeze motion for action shots.

In fact, overpowering ambient light when freezing motion with flash is important, because if the movement is fast and the ambient light isn’t fully overpowered by the flash, movement can still be evident in a photo. To cut out the ambient light outdoors during the day you need a faster shutter speed, and if it’s over the flash sync speed of your camera you’ll need to set your flash to high speed sync.

Another essential factor in freezing motion with flash is flash duration. The faster the movement, the shorter the flash duration needs to be for perfectly frozen motion. Even though to our eyes all flash seems like a really rapid burst of light, flash duration varies.

Strobe and continuous lighting used to light portrait
Lit with strobe (camera left) and blue gel and continuous light (camera right) for a hair light

DISADVANTAGES of flash lighting

1. Can’t see the light

You can’t see where the light will land, so you need to know where to place your lighting for the portrait lighting pattern you want to use when photographing people.

Because you can’t see the light until you take a photo and look at the results on your LCD screen on the back of your camera, it can be difficult to know if the flash is powerful enough, or too powerful.

That’s why I use a handheld light meter to measure the strength of the flash. It cuts down on the faff of getting the exposure right. With a light meter you decide on the camera settings that you want to use and then adjust the light accordingly.

So flash photography is a steeper learning curve for new photographers than continuous light, but it really is worth learning.

2. Need a trigger / remote / transmitter

Speaking of extra equipment, when using flash you need something to trigger it when you push the shutter button so that the flash of the strobe syncs with the split second that the shutter is open. You can do this two ways:

  • Use your pop up flash to trigger your off camera flash (aka strobe)
  • Use a remote fitted to the hotshoe of your camera to trigger the flash by radio frequency

Flash sync speed varies between brands, but is between 1/100th and 1/250th shutter speed. If you use a faster shutter speed than the sync speed of your camera allows, there’ll be a black line in your images. Unless your strobe has a high speed sync function. In which case, you can shoot at very high shutter speeds.

3. Multiple flash units

If using speedlights, rather than larger strobe lights, you may need several flash units to emit enough power when photographing outdoors on a bright sunny day.

It all depends on the power of your flash.

4. Flash recycle speed

Some flashes recycle faster than others, with the more expensive, higher powered strobes being the fastest. Flash recycle speed refers to the time it takes to recharge between flashes.

A fast recycle time is particularly important if shooting with flash in burst mode. Examples of when you would need a fast recycle speed include:

Two types of LED panel lighting for continuous light
Two examples of continuous lighting – both are LED light panels

ADVANTAGES of continuous lighting

1. You can see the light

The most obvious pro of constant lighting is that you can see the light, which is a great advantage, especially for portrait photography.

That said, many studio strobes also have a modeling light, which you can turn on during set up to see where the light is falling on the subject. But not all have this function and speedlights definitely don’t.

2. Supplement window light

Continuous light works best indoors as a supplement to window light, so that you can use a lower ISO for less noise in images.

Just make sure that you can adjust the color temperature of the light to match the natural light coming in the window so that you don’t have two different light colors. Using your camera’s white balance presets you can set the white balance to:

3. No added gear required

Because continuous light is on constantly, you don’t need any further equipment to trigger the light. So it can be quicker and easier to set up, especially if you don’t have an incident light meter.

4. Good for video

Continuous light is used for video, making it a versatile lighting kit to have if you shoot both still photography and video.

DISADVANTAGES of continuous lighting

At first glance continuous lighting might seem like a good idea, but there are some definite disadvantages of constant light.

Examples of balancing flash with natural light
On the left the exposure settings are not right (aperture F2.8), so the sunlight on her hair is too bright. For the image on the right I adjusted the aperture to F3.2 and increased the power of the flash. The background is darker and the sun on her hair is correctly exposed. This shot would not have been possible with continuous light

1. Lack of power in bright conditions

The main disadvantage of continuous light is that it’s not as powerful as flash, so might not be powerful enough to compete with natural light outdoors on a bright day.

If, for example, you use the sun to backlight your subject, you need to be careful that the highlights on their hair aren’t blown out. So your lighting needs to be powerful enough to light the face while exposing for the background and highlights.

How well it copes depends on the continuous light kit. As with most things, you get what you pay for. So I’d suggest paying a bit more for the versatility of more powerful constant lighting.

2. Slow shutter speed and higher ISO in low light

Oddly enough the opposite is also true, in that many constant light kits don’t offer enough power for low light situations.

Because constant light isn’t as powerful as flash, to shoot in low light conditions you’d have to use a slower shutter speed and possibly also a higher ISO in low light conditions than you would if you were using strobe lighting.

The alternative would be to ensure that the light is as close to the subject as possible without getting into shot, or you’d have to remove the light afterwards in Photoshop.

LED lighting with warm and cool color temperature lights
Left photo is the LED panel switched on. Right photo is a a close up of the lights – you can see cool, white LEDs and warm, yellowish LEDs. These can be adjusted to make the light warmer or cooler

3. Color temperature

Constant light can often be either too warm (tungsten light) or too cool (some LED panels and also some modeling lights on strobes). So make sure to read product reviews that mention the color temperature of the light.

However, many LED type constant lighting kits are fitted with both warm and cool color temperature light, which is convenient when shooting in different lighting conditions.

4. You can’t freeze motion

Because of the lower power, and the need for a slower shutter speed, you can’t freeze fast movement with continuous light.

Infographic of flash vs continuous light

Infographic of flash vs continuous light
A quick summary of flash vs constant lighting

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If you have any questions about flash vs continuous light, let us know in the comments.

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