Flash at night - pros and cons

An evening on the West Coast Trail

Using flash at night, or even at dusk, has both advantages and disadvantages.  The power of the flash, the distance the subject is away, and the ISO of the sensor all dictate its working distance.  As you can see in the top photo the background becomes darker as distance increases.  The foreground is nicely lit up and allows a fast shutter speed to freeze motion.  You can see my daughter, Leanne (far left) playing with her fire stick - the moment is captured in time.  Without a flash, the shutter speed must decrease significantly.  In the bottom image, you can see her significantly blurred as her play is slowly rendered.  Flash freezes action and illuminates the only foreground.

When flash is not used in very low light situations long exposures are required.  The other option is to use high ISO values, which produces a great deal of noise.  The amount of noise produced is highly variable, but smaller sensors and longer exposures increase it as well.  I prefer to use low ISO values with long exposure noise reduction turned on.  The bottom image was shot at 100 ISO for five seconds at an aperture of f/5.0.  Even then it is somewhat underexposed, but I wanted to capture details in the fire.  The relative darkness of the event helps set the tone of the shot, which is lost when flash is used.  Not using flash blurs action and gives natural light the task of exposing the image, producing a softer, more evenly lit scene.

You also have to consider the need of a tripod or some other way to immobilize the camera when doing long exposures.  Vibration compensation helps mitigate blur due to a camera being handheld, but only within 3 or 4 stops of the standard 1/shutterspeed rule of thumb.  With a focal length of 45 mm on a full frame camera, a shutter speed of 1/50th of a second would suffice with no vibration compensation or a shutter speed of 1/5th of a second with it.  At 5 seconds the entire shot would be ruined if it was handheld, vibration compensation or not.

At the end of the day, it is always a good idea to try to do things in multiple ways.  Experience tends to be the best teacher; I have always found it is the best way to learn.  Of course, it takes time and some degree of organization to do this.  As well, you have to take your camera off full-auto because it will dictate how the shot will be orchestrated.  It will mean having to pay attention to settings and even understanding what they all mean.  Scary for some, but it is the best way to learn.

Thanks for reading.  www.ericspix.com