What Are The Advantages of Studio Flash Lighting?

Studio lighting can be broken down into two categories, continuous and flash. While continuous lighting has two main advantages there are many disadvantages.

The good points of continuous light:

It's inexpensive, and makes a good starting point for anyone on a small budget.
You can see what the light is doing and where the shadows and highlights are.

We have all taken photos in artificial light and ended up with yellow pictures! To your eyes, the light from a tungsten bulb looks white, but it isn't. Colour temperature  is measured in degrees Kelvin, daylight is around 5,600K and a tungsten bulb is more like 3,200K and therefore records on daylight balanced film as yellow.

This can be overcome in three ways: Firstly, you can use tungsten balanced colour film. Secondly, you can put a filter on your lens, which will enable you to use any daylight film.

Modelling Lamp

Studio flash units are fitted with a continuous lamp, which can be seen on this photograph sitting in the centre of the circular flash tube. Because of its position it gives a very accurate indication of the angle and quality that the flash will produce when fired. This makes your lighting easy to set-up, because'what-you-see-is-what-you-get'.

As this lamp is relatively low powered you don't get the heat or brightness problem we talked about with continuous light. The only thing to remember is that the flash will be a much stronger light, so the shadows will be darker and the highlights will be lighter.

To trick your eye/brain built-in compensation device when setting up lighting, first close one eye then squint through your lashes. This has the effect of increasing the contrast level you can see and is much more like what the camera will record. Don't forget to tell your model what you are doing or they might think you rather strange!

Consistency

Remember how we said that as a tungsten bulb burnt it got more and more yellow? Well with flash every time you press the shutter the colour of the light from the flashtube is balanced to daylight. This means that you can use any film you like without the need for filters, even with slide film - no problem.

Power

Modern flash units give huge amounts of power, released in a fraction of a second. For most home users a unit with a power of 250, 300, 500 or 600 watt/seconds is usually sufficient. Watt/seconds or Joules is the measure of the power that a flash unit can produce.

Don't get confused with guide numbers, this changes by changing the accessory on the front! A 300 w/s unit is half the power of a 600 w/s unit, which is exactly one f-stop.

So if your 600w/s unit was set up two metres from your subject and you were getting a flashmeter reading of f/16, then a 300w/s unit in the same place would give a stop less at f/11. We will cover what a flashmeter is and how it should be used in a later article.

Control

It's all very well having lots of power, but it's no use if you can't control it! Even the most simple and inexpensive studio flash units have at least a 'full/half power' switch, most will offer much more control.

Remember, we said that if you turn a flash head down to half power you are reducing the output of the light by exactly one f-stop. Smaller reductions in power with a simple head are obtained by moving the head further away, or closer for more power.

Just remember the Inverse Square Law which basically means that if you move your light source twice as far away, you will lose two f-stops of exposure. e.g. Our head is one metre from our subject, using ISO100 film we are getting an exposure of, say f/16. If we move the head back to two metres away our exposure will be f/8, - two f-stops less.

Monoblocks vs Power Packs

For most uses Monoblock, or Compact Flash Heads as they are normally called, will do most of what amateurs and most professionals require. Compacts have all the electronics built into the head, whereas a Power Pack will have a separate floor standing unit with all the electronics in and a separate head, or heads, that are plugged in to this.

The head contains a lamp holder for the modelling lamp, the flash tube, simple circuitry and normally a fan to keep it cool.

Power Packs are generally used when a huge amount of power is required and when the units are going to be used at high speed over long periods e.g. for fashion photography.

The parts that generate the most heat are housed in the head away from the electronics in the pack, which is also fan cooled. With the new generation Compacts, such as the Elinchrom Style unit above, many of the advantages of the pack have been removed.