Flash – what is it capable of?

Let's start simple, with an obvious candidate for flash use: photographing in low light, with a flash on the camera, and the flash pointing towards the main subject.

The flash brings its own harsh, directed light into the photo – it is now bright, goal achieved. But at the same time it covers up the weak ambient light, the effect of the picture is different.

Picture atmosphere and blur because of long exposure times have to be weighed up. In this candlelight situation, I took several shots with an exposure time of ¹⁄₈ s – freehand, highly likely to get blurred. In the small picture are extracts of two shots; the result can still be ok or clearly unsharp. Of course this can vary a lot  depending on circumstances; on whether peaople are talking and moving, whether you can rest or prop the camera somewhere, if you have the opportunity to take a series of several shots to pick the sharpest one etc.

Also, because of the image stabilisers that are so common in cameras today, it is quite possible to get a sharp image even with long exposure times. Sorry, there is no definitive recipe, you have to use your own judgement, experience and trial and error. If you are just starting out in photography, try taking pictures with and without flash in low light.

The fill flash is a flash supplementing bright ambient light, typical situations are

• a main subject in backlight, thus much darker than the background
• Lightening shadows, especially in direct sunlight, which creates harsh shadows.

First, about brightening shadows: Freddy sat down in the garden in the sun for one photo without and one with fill flash. Direct sunlight is not suitable for photos of people because of the harsh shadows, not to mention that photographed people often have to blink and it is uncomfortable for them. Nevertheless, here is the example photo, one without and one with automatic fill flash.

A second shot a few metres away brings the second situation, the main subject darker in the shade against the bright lawn in the sun. The effect of the flash is obvious.

In both photos, the face is now quite evenly lit, already slightly unnatural. We will improve this later with a flash exposure compensation.

The flash duration is of the order of approx. ¹⁄₁₀₀₀ s with a really powerful attachable flash at full power and only a fraction of this when the flash is weaker or not emitting its full power, order of magnitude: approx. ¹⁄_10,000 to ¹⁄_40,000 s.

This short flash time is great for freezing motion or creating an additional sharp, partial image within a shot with motion blur. The photo of a small remote-controlled helicopter has both a circle of the rotor blades rotating during the exposure time and a clear image of the rotor from the very short flash.

This is a wide topic, from simple solutions that can be done inexpensively with any camera up to expensive professional setups for which a photographer has several assistants to transport all the equipment and set it up for an elaborate shooting.

Here are possible applications requiring little effort for hobby photographers:

Indirect flash is a simple way to change the hard, head-on flash into a soft, side-on or top-on light. It requires that you have a separate attachable flash for your camera, where the flash head can be rotated.

The flash shines on a wall or ceiling from where the light falls on your subject. The light gets the colour of the wall, which can give welcome effects, e.g. when a wooden wall gives the picture a nice warm colour, but it can also lead to colour casts. You have to look anew to see what is suitable in every shooting situation.

An off-camera flash is placed beside the camera, illuminating the subject from the side. There are several ways to trigger such a flash:

• A cables that you plug between the camera's hot shoe and the flash.
• A flash on the camera – the small built-in one or an attached one – triggers the stand-alone flash via infrared signal.
• A remote control attached to the camera (accessory) triggers the stand-alone flash.
• The stand-alone flash has a trigger mechanism that reacts to other flashes. This works simply and with any camera, regardless of the very specific control systems of the camera manufacturers: 
• One flash is be triggered by the camera, e.g. a small built-in one.
• The stand-alone flash reacts to the abrupt change in brightness and fires additionally in the very same moment.

A softbox is an attachment that, like a lampshade, enlarges the illuminated area and hence softens the light. Here are examples of a very small one that fit on an attached flash on camera and a larger one that only fits on separately mounted flashes. There is a huge range of such accessories in all sizes, price ranges and many small variations. It's easy to end up with expensive studio solutions, but simple accessories like the one shown here make already a huge difference.

A small softbox can be useful and quite effective at short distances. A larger one will of course give even softer light, and can also be placed a little further away. You need a tripod or a comparable mount. And the handling becomes more complicated, a flash unit on a larger softbox like in the example photo has to be triggered wirelessly. Many cameras can do this today, but that would take us too far on this page.