Dragging Your Flash Can Be Enlighting !

The light from your camera’s flash travels a further than you might think. So why is the background pitch black in some of your photos and nicely lit in other photos that you photograph?

Now before we go any further, I am referring to photographing in an environment where the background is not brightly lit by the sun or room lights, but there is still some sort of lighting (sunset, buildings, table lights) . So think of when you photograph indoors at a church or party or when outside at dusk and you want to have some of the room or background behind your subject lit. 

First let’s look at two things:

  • What controls the light on your subject ?
  • What controls the light behind your subject ?

It is after all the same light from your flash – but it’s two different settings in your camera which controls it.

For those of you who use the automatic setting on your camera you are basically letting the camera make all the decisions for you regarding how the subject and background will be lit.

If you want to better control this there are three main setting that you can make

  • Aperture – this is how much the shutter opens
  • Shutter Speed – this is how long the shutter is open
  • ISO  – this is the speed of the film (although in a digital camera it controls how sensitive the camera’s digital sensor is to light.

A light meter is a device you see the  photographer hold in front of the subject and then test the flash. The meter tells the photographer approximately how to set their camera for a correct exposure.

OK, so let’s say that the meter  says that the light on the subject is perfect at ISO 100, 100/sec (shutter speed) and F8.  You set your camera to those settings and take the shot. The subject looks great, but the background is pitch black.

The technique to allow you to extend how much of the background is lit is called “dragging the shutter”.  It simply means setting the shutter speed to a slower speed (try 50/sec) , allowing the shutter to stay open longer and the camera’s sensor sees more of what is behind your subject.

Aperture controls the light on your subject and shutter speed controls the light seen behind the subject. So we didn’t change the aperture, we changed the shutter speed.

But you don’t have a flash meter !  OK, you’ll have to do a bit of trial and error. Give this  a try. Set the aperture to f8 and 100/sec and take a flash picture. If the subject looks great you now know the correct aperture setting.  If the subject is too bright just change the aperture to a larger number .. like F11 and take another picture.

The next step is to set the shutter speed so that the background is lit the way you want it.  If it’s too dark at 100/sec, go to a smaller number like 50/sec More of the background will be lit because the lens is open longer and it’s “seeing” a bit of the ambient light (filtered sunlight, table lights) . To make the background darker do the opposite and set the shutter speed to 200/sec and like magic the background will be darker.

So let’s start you with lighting the subject and a bit of what’s behind them by dragging the shutter .. OK?  You do that and your photography will be take a huge leap. OH YEA!

Here are some examples of dragging the shutter – in every picture the aperture is F5 – which correctly lit the subject (the sign).

WalDrag030716-2573

This shot was done at an aperture of F5 and a shutter speed of 200/second – the background is almost black ( and and when I shot this there was filtered sunlight on the background)

WalDrag030716-2574

This shot was done at an aperture of F5 and a shutter speed of 100/second – Half the shutter speed of the picture above – The background is a tiny bit brighter , but still too dark

WalDrag030716-2575

This shot was done at an aperture of F5 and a shutter speed of 50/second – This is half the shutter speed of the picture above – but remember, the aperture has remained F5. The background is even brighter

WalDrag030716-2576

This shot was done at an aperture of F5 and a shutter speed of 25/second – the background is very bright, but because of this slow shutter speed it is best to use a tripod.

 

Dan Busler is a professional portrait, performance and event photographer with studios located south of Boston in Walpole MA. He also offers camera instruction for the new DSLR user. You can see more of his work at http://www.danbuslerphotography.com

 

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