Long Exposure Photography or slow shutter photography is using long shutter speeds to capture stationary, static objects while blurring out the moving elements.
Most commonly used for night photography, stars and moving water, it is also used for fireworks and light painting. An added bonus in high traffic areas, is if the exposure is long enough, pedestrians will completely disappear.
Long exposure photography is easiest in low light situations such as at night, but with the addition of ND filters, can also be done successfully even in bright sunshine. ND Filters (Neutral Density) are exactly that, they are neutral and should add no colour at all to your image, but simply reduce the light entering the lens. ND filters come in different strengths from .06ND and up with the .06 giving you a two stop reduction and the ND 3 (also referred to as an ND1000) a ten stop reduction.
A tripod is essential for all long exposure photography as you are using speeds beyond what can be hand held with stability. Turn the image stablisation off on the lens while its on a tripod and use either a remote switch to trigger the shutter or the timer function as the slightest movement of depressing the shutter can blur image. The same goes for bridges etc., if you are on a bridge trying to get a shot, and someone starts walking across just wait till they are gone.
Light painting is best accomplished in bulb mode. Set your ISO to 100 to limit the noise and make sure noise reduction is turned off on the camera. If you are interested in Light Painting I can highly recommend the events run by Melbourne Light Painting.
One of my favourite long exposure subjects is water. Waterfalls, streams, rivers, ocean tides and waves…. and this is where the ND Filters come into their own to give you the milky fairy floss water or mist. For early mornings or late afternoon an ND2 or ND4 is sufficient. For bright sunshine you’ll need to get out the ND3. You can also stack the filters, but be aware if your filter gives off a slight colour cast, stacking them will magnify the result. I started off with the round screw on filters, but have now moved to the square ones as I wanted to add graduated filters to my pack. Variable filters are something you want to avoid at all costs. They leak light and give you terrible results. To do a long exposure of water.. set your camera to Apeture Priority, ISO 100 and the F stop you prefer and take the shot. Note the shutter speed and using an ND calculator for android or iphone, calculate the shutter speed for the long exposure. Move to manual mode, use the same F stop, Focal length and ISO. If using an ND ten stop.. it will be so dark you need to focus on your subject before the filter is added, then move the lens to MF (as once the filter is on its so dark you cant focus) Once you have done your settings, add the filter and take the shot.
Note: if the water is moving fast such as the falls above a shorter shutter will give you the blurred water. If its slower moving.. or just a trickle… a longer shutter is required, as the speed of the water affects the blur.
If you havent tried long exposure before get out and give it a go… its a lot of fun!