Long Exposure photography is thrilling because the camera is creating something that the eye cannot see. Traditionally, neutral density filters are used to create long exposures but a similar effect can easily be achieved with with editing software. In this tutorial I will show you how to simulate long exposures in photoshop in just a few simple steps.
HOW TO SIMULATE LONG EXPOSURES IN PHOTOSHOP OVERVIEW
Step 1: Load a sequence of images in Photoshop
Step 2: Select all of the layers, Control Click (Mac) Right Click (PC) Choose: Convert to Smart Object
Step 3: Change the stack mode to Mean by navigating to Layer > Smart Objects > Stack Mode > Mean
Step 4: Inspect Image for any defects. Use the clone stamp and healing brush if needed.
NEUTRAL DENSITY FILTERS VS. MULTIPLE EXPOSURES
Creating any good photograph requires a little bit of planning while in the field. Long exposure photography is no exception. First and foremost, I will start off by saying that I’m a huge fan of neutral density filters and advocate for anyone seriously interested in long exposures to own at least one or two physical ND filters. Breakthrough Photography is my ND filter of choice. I especially like their 6 stop Dark Polarizer and their 10 stop ND.
While I prefer to use ND filters over combining multiple shots in post production, there are times where combining multiple shots to simulate a long exposure makes sense. Forgetting your ND filters at home or in the vehicle is probably the most obvious reason to use the technique I’m about to cover but that is not the only reason. If you only own a dense neutral density filter, it may slow down the shutter much longer than you’d like, especially if you’re shooting on the edge of day. In this case it may make more sense to shoot multiple short exposures instead of one really long one.
ISSUES TO BE AWARE OF WITH LONG EXPOSURES
Each long exposure method that I mentioned above has its own downfalls. Using a very dense ND filter or shooting on the edge of day could result in exposures that last 5 minutes or longer. If you mess up the exposure settings, the light could be completely different in the amount of time that it took to take the shot. I’ve have defiantly botched my fair share of long exposures over the years. I recommend practicing calculating long exposures at sunset and sunrise so you get really good at calculating exposure and changing light at the same time. Read my article on How to Use a Neutral Density Filter for more information on calculating exposures.
SIMULATED LONG EXPOSURES
The biggest issue when simulating a long exposure is that there will be a slight time gap in-between shoots. This gap can cause clouds to have a stuttered appearance especially if they are moving fast or your shutter speed is short.Combining multiple exposures in post requires a little more image sorting and leg work than just editing a single exposure.
HOW TO SHOOT FOR LONG EXPOSURE SIMULATION
You’ll want to place your camera on a study tripod to ensure that it doesn’t move between shots. Set the camera to high speed burst mode or continuous shooting. This will allow you to capture your frames in quick succession. It is best to use a cable release or intervalometer in order to prevent camera shake when hitting the shutter button.
Now it’s time to think about camera settings. Having some idea of how you want the end image to turn out will help you decide what camera settings to choose and the available ambient light will greatly effect the amount of time you can shoot for. Bright daylight will yield very fast shutter speeds while early morning or late evening will produce long exposures without any added effort from the photographer.
Try to image how much time in total you want the final image to be. Having some familiarity with long exposures will certainly help here. The longer the exposure is the silkier the effect will be.
For this example let’s say that we want the final image to be two seconds worth of time. Generally you’ll want to set your ISO to its lowest native setting. (Usually ISO 100) Next, you’ll want to close your aperture down somewhere to somewhere around f/16 to cut light and to increase the depth of field. For this example let’s imagine that the ambient light produced a shutter speed of 1/10 second. That’s a relatively fast shutter speed. If we want to simulate a two second exposure, we’d have to shoot twenty frames. It is best to shoot a few more frames than what you think you might use. In this case thirty frames would be a good number of shots. More frames are always better than not enough frames.
NOTE: I recommend shooting no less than ten frames whenever you shooting a faux long exposure since the software uses an average to calculate the effect.
Once you have your settings dialed in, tigger your camera by holding down the cable release shutter button.
Before we assemble our long exposure in Photoshop, we’ll want to do some basic editing in Lightroom or Adobe Camera Raw. I will be using Lightroom in this example. In Lightroom, click on the first image in the sequence of shots. Open up the Develop Module by pressing the D key. Here you’ll want to do any white balance adjustments, color adjustments, lens corrections, and basic tonal adjustments that the image might need. Once you have edited the first photo in the sequence you can then sync those settings across all of the other images in the sequence.
To do this, make sure the first photo in the sequence is selected and then Shift click on the last image in the sequence. Now click on the Sync button in the lower right hand side of the Develop Module. Make sure to hit the button and not the toggle switch. The toggle switch turns on auto sync which will automatically sync any edits in real time whenever you have more than one image selected.
After clicking Sync, a popup window will appear asking you what settings you want to sync. Since we want all of the images to have the exact same settings, you’ll navigate down to Check All and then choose Synchronize.
Now that all of our edits have been synced it is time to open our image sequence in Photoshop. In the filmstrip click on the first image in the sequence and then shift click on the last image that you want to use in the sequence.
Control Click (Mac) or Right Click (PC) on any of the selected images in the filmstrip. Choose: Edit In > Open As Layers In Photoshop…
CREATING A LONG EXPOSURE SMART OBJECT IN PHOTOSHOP
Once all of your images load in Photoshop, I recommend creating a snapshot in the History Window. To open the history window navigate to Window > History. Then Simply click the camera icon to add a snapshot. This will allow you to get back to your original starting point in case you need to use fewer images than what you initially loaded into Photoshop.
CREATE A SMART OBJECT
Now that we are in Photoshop the first thing we want to do is create a Smart Object. To do this, simply click on the top layer in the layers window and then shift click on the bottom layer. Once the layers are selected Control Click (MAC) or Right Click (PC) on any layer and choose Convert To Smart Object.
CHANGE STACK MODE TO MEAN
Once you have created a Smart Object, all you have to do is change the Smart Object Stack Mode to Mean. To this, navigate to Layer > Smart Objects > Stack Made > Mean. By changing the stack mode to mean, Photoshop will average out the pixels in the scene causing anywhere that had movement to become blurry. Zoom into the image to see if there are any strange artifacts that appeared simulating the long exposure. If you find a trouble area such as cloud stuttering you may need to use the clone stamp and or healing brush blend the pixels a little bit. Once you’re finished go to File > Save and you’re all done! The image should go right back to Lightroom if you followed my steps from above.