A famous park bench philosopher once said, “Long exposure is like a box of chocolates. You never know what you’re gonna get”.
(Ok, maybe it wasn't him, maybe it was his momma, and I'm not even sure she was talking about long exposures…)
Anyway, if you’re not fazed by uncertain outcomes and have patience in spades, then you might just enjoy experimenting with long exposure photography.
What is Long Exposure Photography?
There is no definitive formula as to what constitutes a long exposure photograph. So let’s just consider it to be any image where a slow shutter speed has been deliberately chosen as an artistic technique to emphasise movement or convey the passing of time.
As long as your camera remains still, static elements will appear sharp while moving ones—such as clouds, water, traffic or stars—will appear blurred or, in some cases, virtually disappear. The longer the exposure (or slower the shutter speed), the greater the blurring effect.
Long exposures are a staple of landscape photography and sometimes architecture photography, giving water and skies a dreamy feel. But they also allow you to capture light trails, paint with light, and produce creative effects in a wide range of situations.
Neutral density filters reduce the amount of light entering your lens, thus allowing you to slow your shutter speed and maintain correct exposure. They’re essential for many kinds of long exposure photography.
ND filters come in a range of densities that correlate to an exposure reduction in stops. For example, if you shot an exposure of f8 @ 1/30 sec then added a 3-stop ND filter (sometimes described as an ‘ND8’ or ‘ND 0.9’ filter), your new exposure would need to be 3 stops slower – i.e. f8 @1/4 sec. For more info on ND filters, see Filters Explained.
Which ND Filters to Use for Long Exposures
I often get asked which is the best long exposure filter, to which I like to respond with the infuriatingly non-committal “It depends”.
It does depend. It depends on the time of day you’re shooting and the amount of ambient light in your scene. It depends on the speed of movement in your scene. And it ultimately depends on the degree of motion-blur you wish to capture to create the effect (or mood) you’re after.
2-stop ND (also known as ND4 or ND 0.6) filters and 3-stop ND (also known as ND8 or ND 0.9) filters are great for photographing light trails at blue hour. During the day, they also work well for smoothing water in scenes while retaining a bit of texture.
Extreme ND filters, such as the LEE Filters stopper range, are a highly effective tool that enable you to shoot with very slow shutter speeds.
A 6-stop ND filter (a.k.a. ND64 or ND 1.8 filter)—like the LEE Filters Little Stopper or LEE Filters 100mm ProGlass IRND 6 Stop Filter—reduces exposure time enough to capture movement and show the passing of time, while still retaining texture in your scene. I find the LEE ProGlass IRND 6 Stop Filter particularly useful in the earlier and latter parts of the day when light levels are lower.
A 10-stop (a.k.a. ND1024 or ND1000, or ND 3.0) ND filter like the LEE Filters Big Stopper or LEE Filters 100mm ProGlass IRND 10 Stop Filter will knock a huge 10 stops from your shutter speed. It’s guaranteed to blur anything in your frame that is moving. In lower light conditions, the a 10-stop filter will smooth out motion in water and clouds, resulting in an ethereal feel. In brighter light, a 10-stop ND will yield a similar result to that of a 0.6-stop ND in lower light – usually some blur but with texture retained.
At the more extreme end of the ND filter range is the LEE Filters Super Stopper or LEE Filters 100mm ProGlass IRND 15 Stop Filter – equivalent to ND32768 or ND32000, or ND 4.5. If you lack stamina, then this filter is not for you. When you set out to shoot with the Super Stopper or 15 Stop IRND, which both cut out a whopping 15 stops, pack a decent lunch. Seriously, though, this type of filter is not intended for use in low-light conditions. The purpose of a 15-stop ND is to make shooting long exposure during the brightest part of the day possible. The blur that results from its use introduces a softness to images that would otherwise feel quite harsh, thus unlocking those middle hours of the day that are typically avoided by photographers.
It’s not difficult to use light-stopping filters to create long exposures. But for best results, be sure to follow these critical steps:
1. Steady Your Camera
Position your tripod on a stable surface, mount your camera securely to the tripod, and turn off your camera’s or lens’ vibration reduction (or image stabilisation) function. This will stop your camera or lens from ‘hunting’ for camera movement – a process that can actually create movement in a stationary camera.
2. Compose and Focus Your Image
If you use autofocus, switch your camera to manual focus once you have finished focusing. Your camera will essentially be blind once you add a filter to it, so if left in autofocus mode it will attempt to refocus when you press the shutter.
3. Dial in Your Long Exposure Settings
Set your camera to Manual shooting mode and select your desired aperture and ISO. Meter your scene to find the appropriate shutter speed for the exposure you’re after.
For LEE Filters users: If you are using a grad filter with your stopper, you should have this in place prior to metering. (Note: Leave the inner guides of your filter holder free for the stopper.)
4. Test Shoot
Take a test shot and check the histogram to make sure you're happy with the exposure.
5. Attach Your Filter
Attach or insert your ND filter (depending on whether you’re using a screw-on, rectangular or drop-in filter). If using the LEE Filters system, slide your chosen stopper or IRND filter into the guides nearest the lens.
6. Adjust Your Shutter Speed
Reduce your shutter speed by the number of stops corresponding to the filter you are using.
If you’re sleep deprived from rising at 4am to catch the sunrise, or just hate maths, the good folk at LEE Filters have kindly included a handy little exposure table with each stopper to help you work out the correct exposure. Alternatively, there are LEE Stopper and ProGlass IRND Exposure Guide apps that are free and extremely easy to use.
7. Connect Your Cable Release (if Exposing for 30 Seconds or More)
If your exposure is longer than 30 sec then you will need to wind your shutter speed to ‘Bulb’ and connect your cable release if you haven't already done so.
8. Cover Your Viewfinder
To avoid any excess light spilling onto your sensor (or film), cover your viewfinder before pressing the shutter or cable release button.
Special ND filters (like the LEE Filters IRND range) are designed to block infrared and/or UV light, which can create colour casts. When using standard ND filters, however, you may notice a slightly cool colour cast in your images. This is easy enough to correct for. \
Either take a test shot and adjust your white balance in camera or shoot in RAW format (as is ideal) and simply adjust in post.
On more than one occasion I have chosen to leave the colour cast in my final edit because the effect suited the mood I was aiming for.
Experiment, experiment and then experiment some more. Try going out at different times of the day. Try shooting in different weather conditions – bright sun, stormy clouds and everything in between. Try using different strength ND filters. But most of all, let go of steadfast expectations and enjoy the process, because you never know what you’re going to get.