How to get rid of people (with Photoshop)

    Almost every photographer has experienced this: You want to get pictures of a building or a landscape and there's too many people around.

    I've had times when I just wanted to unload a fire-extinguisher-sized can of pepper spray on people who were ruining my otherwise good shot. But there are a couple ways to make the crowds disappear that won't get you a criminal record.

    However, both require an investment of time — and a tripod.

    The first involves the oldest camera trick in the world. It's how early photographers got cityscapes in broad daylight that were devoid of people: Long exposure.

    Back in the day when ISO, if it could have been measured, was in the single-to-low-double digits, a photograph could take anywhere from a few seconds to a minute or two to expose. Most people walking about in such a photo would not register on the plate. Only people who didn't move too much would show up as ghosts, though.

    We can achieve the same effect today, even with cameras that have faster sensitivity levels at their lowest end than Louis Daguerre could have imagined possible.

    First, mount your camera on a tripod. Unless you are dead, you won't be able to hold it still long enough.

    Second, stop down your lens as far as you can and then, if that's not getting you a speed slow enough, put on a neutral-density filter. Variable ND filters, either professional or one you make yourself, will let you adjust it to get the slow speed you want.

    (If you really want to go hard-core, use a piece of welding glass, but just remember that you'll have to do some serious white-balance adjustment later.)

    Third, use a remote shutter release to take the picture, and if it works out, it should look like a ghost town.

    The other way allows you to use more normal shutter speeds but gets you the same result, although it may take more time.

    With your camera mounted on a tripod (because you don't want the camera moving around between pictures), take a series of pictures of your subject, making sure that you get people in different spots as you take pictures. Here's the set I shot while visiting The Alamo recently.

    If you notice, there's always somebody in the picture, but they're not always standing at the same spot. That's going to be important in just a bit.

    Bring the photos into Photoshop as layers in the same document and then auto-align your layers. Even if you did this on a tripod, this eliminates any accidental jostling of the camera between shots.

    Then, create a smart object with your pictures and, after it has finished that task, set the stacking mode to median. When you do this, Photoshop looks at your pixels as values, and as it compares the different pictures, it will use the pixel that is the average of the collection. What this means is that it will more often than not pick the pixel that has nobody in it and leave you with a scene devoid of people.

    It's not a perfect process. In my pictures, the guy in the red shirt didn't move far enough in two pictures, so there was some residual red left on the stones. Plus, the flag was fluttering a bit, which created some interesting ghosting. But the fix is to go back inside the smart object, find a clear spot for that section of the image and copy and paste it into the final picture, making sure you feather it sufficiently so that it doesn't look like a kid used a cutout and that paste-like glue they used to have in elementary schools that you applied with a tongue depressor.

    This is what I got:

Look, Ma, no tourists.

Make your own variable neutral-density filter

    We've all seen the long-exposure shots of waterfalls where the water's silky smooth, or the clouds just streak across the sky.

    The technique can also help eliminate crowds from pictures, especially if they move fast enough.

    The problem is, if you try to do them in daylight, you can't stop down far enough to get the really smooth effect. Even if you set your ISO as low as the camera permits and use the smallest aperture, you might be able to get a second, at most.

    One way to reduce the amount of light coming in is to use a variable neutral-density filter, which allows you to dial in the amount of light-blocking you need to lengthen out the exposure.

    But if you can't find one, or afford one, there are a couple alternatives. This time we'll talk about using a pair of polarizing filters to do the job.

    As you know, a polarizer works by blocking light coming from particular angles. Normally, photographers use the filters to darken the sky, increase contrast or eliminate reflections.

    But if you put two of them together, you wind up blocking most of the light coming into the camera. Try looking through a polarizing filter while wearing polarized sunglasses, and you'll see the effect.

    To do this with a camera, you need two polarizing filters screwed together and then placed in front of the lens. By turning one of them, you can darken the image to the point where you can get a long exposure.

    Here's a photo taken without the filter in place. It's about 1/25 of a second.

 

    You can see the water in the pond doesn't look smooth, and the water cascading down the rocks has some detail in it.

    Here's the same shot at 81 seconds.

    Now, we have the smooth water and the streams almost look like a mist. The only drawback to this method is the blue cast from the filters. But I was able to fix that by increasing the color temperature.

    You'll need to lock the focus in before you darken the filters, and it may take some guestimating on the exact exposure, but the effect works.

    Next time, I'll show you a way to do it without a filter, even in broad daylight.