Have you ever looked at an image or movie, and then wondered how many people are there really there when several are the same person? That is a little of what we will cover today: multiple exposure. There are two types of multiple exposure, in camera and out of camera. With today’s digital cameras, it is difficult to get the double exposure if not impossible. This makes it so that you have to use photoshop for the double exposure and manipulate the image. The neat part of a double exposure is that you can create as many of any object that you want in an image. The only real restriction is keeping the light similar. Alternately, it may be the amount of space in your photograph for the number of images. Usually, these are the limits to people who take double images.
Did I hear someone say “green screen” or “Chromakey”? I actually want to persuade not to use a Chromakey background. I have used a few of these, and I have found that a simple grey background works the best. The problem with the colored backgrounds is that it is difficult to keep their colors from spreading into the subject. You will see this most with anything that is shiny or when you heavily back light your subject. Everywhere there is a reflection or spill, you then have your background behind the subject seeping through. So, my recommendation is to stay clear of Chromakey unless you are doing video work.
So, what do I use for a background? It can be anything. Probably the easiest thing to use is all black. Alternately, you can use all white or all grey. Any will work. You can also use something around you, depending on the image you want to create. The key is to think about what you are doing. As a photographer, think about what you are shooting and if the light is constant. Think about what you will be doing and which will give you the best separation. If you are using natural light, you may have a restriction of light changing if you are taking several images. You will need to keep this in mind.
Next is the subject for the image. What will it be? It can be anything you want it to be. Most often, it is a person or a pet. But, it could be just about any object you want. Recently, I was looking for at a blog where the person took about $200 and replicated it all over the person’s living room area making it look like the person had a few million dollars. That image took a little while to do, and some serious patience. For your first few projects using multiple exposure, choose something simple and maybe two or three replications. Don’t try to do something that is complex. Try something simple and get a feel for how to do this. Then build up to more. If you are overlapping your images, think about how they will overlap. Remember that lighter areas can overlap without impacting the image in any way, and darker areas will impact the image.
So, now we have our background, lighting, and subject. We also have some idea how many subjects there will be. The next part is key: get as sable a camera stand as possible. For most people, this will be a tripod. If you have an inexpensive tripod, get a 10 or so pound weight and hang it evenly under the stock of the tripod (the part where the three legs come together). The added weight will make the tripod more stable. Also make sure that the place you stick your tripod is stable and safe for the camera. This comes into place if you are putting your tripod on dirt, gravel, mulch, or similar type surface. You don’t want your tripod sinking as you take the images, or worse, sinking and falling with your camera and lens (and breaking one or all of them).
The last part is to set up the camera on the tripod, frame the area you want to capture. Make sure you meter and then focus. I usually use a center spot for focus and then once focused, turn the auto focus off. You don’t want different focus planes in an image with multiple exposures. Finally, choose an aperture that is fairly closed life F8 or F11. You don’t want any of your subject out of focus… or maybe you do.
The next part is to capture the image. With old film cameras, you just don’t wind the film and snap your next image. You are pretty much done at this stage. For digital, you have to do this in photo shop, so take an image of your subject in each place you want it. This should be fairly quick. If you have a lot of images (more than five) to take, then make sure your light stays the same. Be sure to take one image without your subject in the background. That is the one you will use to build the image on.
Continuing on with working on this with photoshop, you need to process them all the same way and import them all as separate layers in your photoshop image. This is something fairly easy to do and there are a few ways you can do this. Once they are all in, you need to align the images. I find that in every three or so images, you have to nudge at least one of them about a pixel to look right. Once the images are in photoshop and lined up, all you do is put a layer mask on your layer, and then color out your subject and it’s shadow. I typically will use as large and soft a brush as i can use for the initial color out, then go back with a smaller brush and color out the finer details. You may have to play with brush opacity a little to get the detail you want, too. Once you have done this, press control-i to invert the mask, and you have your person there. Remember that one image with just the background – it should be the bottom most image. Then, stack the other images based on what is further back in the image. The further back the subject is, the lower in the stack it should go. Once you have this done, you should then have your multiple exposure image.
There you have it. Any comments or questions are welcome. Thanks to Mariah for being the model for this post.
All information and images are ©2012 Don Krajewski on this post.
XOIND Studios Blog 
Posted on March 17, 2012
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