Continuous lighting or flash? Which is right for you?
Which should I buy – continuous lighting or flash? This is a common dilemma for new photographers wanting to step out into using studio lighting. I often find students unsure which would be the best buy for them. So, I thought I’d share with you in this blog post what I normally tell them. Nobody wants to buy gear that isn’t suitable. Buying the wrong type of lighting means you’ll soon be off spending even more money. As with any purchase, there is a certain element of risk that you have to embrace. However, you can minimise that risk by being well informed when you come to make your choice.
What are the advantages of continuous lighting?
With continuous lighting you can see how the light falls on your subject as soon as you switch it on. You don’t have to wait until you’ve taken a photo to get an idea of what kind of image you’re going to end up with. When I’m teaching people who are completely new to studio lighting this is a really helpful feature. I can show everyone at once what effect moving the angle of the light will have. If you are interested in still life photography or product photography then continuous lighting can be easier to get started with.
There is less technical knowledge needed compared to using flash. You can shoot using automatic mode if you really want to (preferably the one that doesn’t allow flash). The camera can calculate the exposure for you based on what it sees. So, if you are newer to photography this makes it considerably easier.
You don’t need triggers. Flash lighting needs to be triggered. Continuous lighting doesn’t – it is simply switched on independently of your camera when you are ready to shoot. This could save you having to buy a set of triggers. Also, for many types of flash you would need to have one trigger per light – which of course puts the cost up. As well as the cost, there is less to set up with continuous lighting as triggers are not needed, saving you time.
What are the disadvantages of continuous lighting?
For portraits there is a real danger of your subject having a strange expression due to them squinting. Shine a bright light at someone for any length of time and they will want to look away or at least close their eyes a bit. If the light is in their line of sight for your subject then it makes portrait photography quite awkward. You will probably have to ask them to close their eyes and only open them at the last moment before you take the shot.
Continuous lighting is not as powerful as you might think. Although it looks very bright, it often fails to pack a punch. So, the further from your subject it is, the harder it is to get enough light on them. Similarly, although it can be quite effective in a dark or dimly lit room, it may not be powerful enough if there is strong natural light present. If you light a candle in a dark room you can see its effect clearly around the room. However, light the same candle outside on a sunny day and you won’t see much impact at all. The environment you plan on using your lights in plays a big role. If you can control the natural and ambient light sources to keep them low enough so they don’t interfere then all is well. However, your continuous light units may seem a bit weedy once you are in an already bright location.
Your light can be a funny colour. Many forms of continuous lighting are not neutral white. If you are using tungsten lighting then you will get an orange glow. This isn’t the end of the world as you can correct the white balance either in camera or later using software. But, it does mean that things will look a bit off-white to you. Fluorescent lighting can cause similar problems, giving you a colour cast rather than pure white. LED panels are often more neutral. Some are adjustable so that you can create a warmer or cooler light depending on your preferences.
Your lights can overheat. Older lights such as tungsten lights create light by heating something up. So, not surprisingly the lights can get rather warm. This isn’t too good if you are photographing anything heat sensitive. It can also make the working environment rather warm. In extreme situations the light may blow due to overheating. Be careful about buying very cheap tungsten lights if you plan on using them for a long period. The longer you have your bulbs on, the warmer they tend to get.
If you want to freeze motion you will need a fast shutter speed. The downside of a faster shutter speed is that the sensor then receives less light. This means that your light source needs to be more powerful the faster your shutter speed is.
What are the advantages of using flash?
Flash units are more powerful than continuous lighting. Although the light is only very brief, it can be much brighter. This can enable you to overpower the ambient light more easily. It can also help if you have to keep your lights a fair distance away from your subject. That extra power can help light bigger subjects too, such as group photos or taking images of large objects. It also makes it easier to add diffusing layers in front of your light. Diffusion material will cut down the amount of light getting through. So, if you have more power you can compensate more easily for this loss.
Flash lighting can help to freeze movement. With continuous lighting you need a very fast shutter speed to freeze moving subjects. This can make it difficult as the exposure can then end up being too dark. You need a lot of light to get a well exposed image at 1/1000th of a second or faster. Flash overcomes this in two ways. Firstly, as we have seen, it offers more power than continuous lighting. Secondly, the duration of the flash itself can be used to freeze the movement instead of the shutter speed. With many flash units and speedlights able to flash at 1/4000th of a second or faster you can more easily get a sharp image of a rapidly moving object.
Whilst continuous lighting is on all the time, flash allows you to put a pop of light in at the beginning or end of the exposure. This allows, for example, long exposures to record movement with a pop of flash at the end to freeze the main subject. Whilst this might be of limited application, it is a useful technique to be able to use on occasion. (To find out more about this, search for rear curtain or front curtain flash sync).
There is a wider range of light modifiers available to use with flash lighting. You can easily change the shape, size and hardness of your light using various lighting modifiers. Most flash systems allow you plenty of flexibility to use everything from large umbrellas to narrow snoots. This gives you more creative control of your images. You can control the direction of light more precisely. The beam of light can be widened or narrowed. Gels allow you to change the colour of the light very easily (see our introduction to using flash gels and the article on portraits using flash gels). Extra layers of diffusion material can be added or removed to make the light softer or harder.
Light modifiers also allow you to control the appearance of reflections. Take a look at these two images of the same subject and compare the reflections:
The first was taken using a flash put through a strip box. This gives a long thin strip of light on the bottle. The second image was taken using an LED panel (continuous lighting). Here you see a slightly diffused small blob instead of a long reflection. If you want to be able to control reflections (and catchlights in people’s eyes) then flash gives you more options.
Using TTL (through the lens) technology, some flash units are able to select the right amount of power for you. When set up in this way they fire a pre-flash to monitor the scene before firing the main flash to expose things correctly. This is a very handy feature if you are pressed for time or struggle to work out what power you need. However, it does leave you relying on the camera and the flash unit to talk to each other accurately and it leaves the exposure in their hands. For the sake of convenience you lose some of the precision of manual control.
Speedlights can be very handy due to their size. As they are so small you can hide them in a scene to add little accents here and there. They are, however less powerful than larger studio lights so are not suitable for all applications. In some instances you can get away with using multiple speedlights to compensate for the lack of power.
What are the disadvantages of flash lighting?
The main disadvantage of using flash is that you can’t see what you are going to get until you take the shot. Yes, you can get flash lights that have modelling lamps. However, these are a weak imitation of the real thing. More technical knowledge is required to set up flash lighting for the desired effect (either that or trial and error!). If you are just starting out you may find it hard to anticipate what the light will do. You might find it hard to imagine the direction, intensity, softness, etc without being able to see it. Continuous lighting makes it easier to grasp the basics as you can see everything in real time.
You may need to buy a set of triggers. Some flash units have build in trigger systems. Others require an external trigger. This can mean an extra expense for you, especially if you are using multiple lights, each needing its own trigger. Wireless triggers tend to be best as they don’t clutter up your scene like cables would. However, sometimes it can be difficult making sure that each unit is receiving a good signal (depending on the type of wireless trigger/receiver).
Some lights can be too powerful to use in small spaces or other situations where only a small amount of power is needed. You can occasionally find that even the lowest power setting may leave your image over exposed. So, you may need to have low powered and high powered flash heads if you want to be able to work in low light and bright conditions.
Unless you invest in a HSS (high speed sync) trigger system with compatible lights, you are limited to shooting at a shutter speed of around 1/200th or 1/250th of a second with many flash units. If you use a faster shutter speed without a HSS system then you will find that you get a black line through your image like this:
Cheap units can be inconsistent. Sometimes they fail to fire at the same power setting every time. You may also find that cheap units could be prone to overheating with prolonged use. However, this is a risk not just for flash but also for continuous lighting.
Buying any item of photography gear is an investment. Ideally try out various lights before you make a purchase. This might be done in store, borrowing a friend’s kit or by attending a photography workshop or one-to-one photography training session. Once you know what you want to use the lighting for that should help you decide whether flash or continuous lighting is better for you. Then you need to consider your budget and what power and other features you require. If it is for very infrequent use to begin with you may like to try hiring lights to see how you get on. Flash tends to be the choice of most professionals due to its creative flexibility and power. However, it does rely on you acquiring more technical knowledge to make full use of it.
© Joe Lenton, May 2017
Having trouble deciding what camera to buy? Take a look at our post – which camera should I buy?