From Many To One, Multiple Exposure Photography

Generally, when we take a photograph there is a single scene, one element; and, that is what we expect to see. There are, however, reasons to combine multiple photographs to produce one, more evocative image. This article was supposed to be a presentation I prepared for the Stony Brook Camera Club but due to an emergency, I had to cancel at the last minute. So, I thought of writing this article and sharing it with the members of the club would be the right thing to do.

Why Multiple Images?

We take and combine multiple images for a variety of reasons. Some of these are much more obvious than others but each may deserve careful consideration for their results can be rewarding in their unique ways. Here are the instances I have considered and used multiple images to produce one photograph:

1. Panoramic stitching, not only to cover a wide expanse but also to increase the resulting image size, even in macro photography
2. High Dynamic Range tone mapping, so that a rich range of tones are incorporated in the final image; sometimes even combining this with the panoramic stitching
3. To convey motion and movement, the camera, the subject, or even both
4. To produce impressionist or expressionist results that convey a different emotion than a single photograph might

Methods of Execution

Depending on the purpose, the creation of the many-to-one images vary. For panoramas, we take carefully spaced and angles sequences. HDR tone mapping needs exposure variation on 3-5 frames. To capture motion, we may choose a slow shutter speed. A more impressionistic result may need multiple exposures either done in the camera or in post-production. I will not get into the first two, stitched images or HDR tone mapping beyond showing some examples. The rest of this article will mainly be on producing impressionistic results in post-production.

Shooting For Combined Results

Some cameras allow recording multiple images on one frame, that will work for some. My camera, a Canon 5D Mark II, can record multiple shots on one frame. However, I prefer to record those multiple shots on their own frames and then combine them into the end result in Photoshop. And, it is not difficult or complicated at all, maybe even simpler than in-camera blending.

Whether in camera or in post-production, combining multiple frames into one requires some preparation. Here are the steps we need to execute:

1. Decide on the number of frames to combine, say 10 although any number is fine
2. Pick an f/stop and determine the proper exposure of the object at that, say 1/100 seconds at f/8
3. Set the camera to manual exposure
4. Calculate the exposure by dividing the shutter speed by the number of frames, 1/100 divided by 10, yielding 1/1000 seconds
5. Now the camera set at 1/1,000 at f/8 you are ready
6. Take the desired number of frames and take a few more while slightly moving the camera around the object
7. Try the above with or without manual focus for slightly different results

Blending The Frames in Photoshop

Although you can open the frames you shot in Photoshop one at a time, you need to copy each one on to one of the frames manually. The easiest way to achieve this will go through either Bridge or Lightroom. Simply select the frames you want to combine in the blend, including the extra frames if you shot any in one of these programs and follow the paths below to open them as layers in Photoshop.

In Bridge, follow the menu Tools/Photoshop/Load Files into Photoshop layers

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In Lightroom, right-click on one of the frames then Edit In/Open in Photoshop as Layers

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You should now have a stack of layers in the Layers palette. Click on the top one, scroll down and Shift-click on the bottom one to select them all. The next step is the fun, experimental part where we can try different blend modes for slightly or significantly different results. I suggest starting with either Screen or Linear Dodge (Add) blend modes. Both of these have the result of lightening the result to a different degree using different formulas. Below are the screen captures of the selected layers, blend modes selected, and the resulting image. Note that we have not done any adjustments to any of the layers other than changing their blend mode.

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What Next

As you can see, the blend modes have the effect of similar to adding the exposure of each frame to produce their result although the actual formulas and computations are not exactly the same. To vary the results, there are more experimental steps you can look into. Since all the changes are nondestructive, you can easily reverse them or change them to others.

1. Turn off some layers and observe the result. Remember, you are not trying to produce a perfectly exposed image but to create an evocative image that gives the impression of what you might have experienced while photographing them
2. While all the layers still selected, go to Edit/Auto Align Layers and choose Reposition. This will result in the layers being repositioned to make them aligned with each other as much as possible. If you did not move much or did not change the pitch and the yaw of the camera they may align perfectly and reduce the impact.
3. If the above happens, there is nothing wrong with selecting each layer and moving them a little at a time, even slightly rotating them by using the Free Transform tool (Ctrl-T)
4. Make the blend mode of all layers Screen, then select only every other layer (Ctrl-Click) and change their blend mode to Linear Dodge (Add)
5. While those layers are selected, try other blend modes and observe the results

The core idea here is to experiment to get different feelings from the combined images. There is no formula, just your imagination and perseverance to figure out what works. It is quite conceivable that the set of images you photographed will not work for this process and you may need to repeat the shoot and vary the horizontal and vertical movement as well as the pitch and the yaw of the camera while taking the photographs. If you photograph flowers like some of my examples, you may try to repeat the shoot on a slightly windy day that will add random movements to your frames.

Try Slow Shutter For Fast Moving Subjects

You can also create “multiple images” on one frame by using slow shutter speed, anywhere from 1-6 seconds will give you interesting results. I took a series of such photographs while I was traveling on a train a late afternoon. The moving train, along with my intentional camera movements gave me a collection I called “time compressions.” You will see a few examples of that below. On another occasion, I was photographing a live ballet performance and after a couple of regular shots, I decided to use slow shutter speeds around 5 seconds. The result was very appealing to me. And judging by the fact that they got published in the International Lens Magazine, alongside the works of Lois Greenfield whose work I like very much, the editors must have enjoyed them too.

Use Stroboscopic Flash

You will also see some examples of stroboscopic flash capturing multiple versions of the same flower on one frame in the gallery below. If you are interested in finding out how they are done, I will refer you to an earlier article I wrote about that. It uses a Canon flash but other brands with this capability should yield the same results.

A Very Special Project

I must also mention a very special project for me, the ballet Orchis. Although the entire 30-minute slide show I created uses multiple images more than a few times, one particular sequence I created used the multiple photographs of one flower I took while I rotated it on a base. When I showed the sequence to the choreographer, Viktor Plotnikov, he liked it so much that gave birth to a segment in the ballet. Watch a short part of that video using these multiple photographs of the same flower, turn your speakers on for its original music.

So the main message here is to experiment and allow your ideas to fail. You will find much information, knowledge, and experience buried in that failure if you seek to find them. Here they are, from many to one!