Multiple Exposure and Christmas Lights

Multiple-exposure image created with three in-camera exposures
As I have mentioned in previous blog posts, I have really enjoyed having the multiple exposure feature on my Canon 7D Mark ii. Canon has taken the ability to sandwich multiple photographs in-camera to a whole new level. 

When you shot double exposures back in the good old film days, the results were usually pretty random. A few cameras had the ability to re-set the shutter without advancing the film. For most of us, creating double exposures required either re-loading an exposed roll of film into the camera and shooting over the top of previous images; or, doing physical camera gymnastics to keep the camera from advancing the film in order to shoot an extra image. 

Nikon was one of the first digital manufacturers to incorporate double exposures into their digital cameras. What a wonderful new feature! With these cameras, you decided before you created the first shot that you wanted to make a multiple. And, you created your double exposures with the next images you shot. You could not preview how the images would overlap. The results were better than the old film days, but still left a huge amount to trial and error. (Which is part of the fun and spontaneity of creative photography)

Enter the new batch of Canon cameras. 

With my Canon 7D Mark ii, I can decide after the first shot is made to create a multiple exposure. And, I can use almost any photo on the memory card as the base image, even if I shot it days or weeks ago. Plus, I can preview how the images will overlap, using the Live View feature on my camera's LCD panel. This has taken multiple exposures to a whole new level of creativity. 

One additional exciting feature is choosing how the images will blend. I can choose from the following blends:
  • Additive - takes the exposures and combines them together for cumulative brightness. For example, if I shoot every image with normal exposure and I overlap 3 images, the image will be overexposed; 1 normal + 1 normal + 1 normal = 3x normal or overexposed

    If I shoot underexposed by 2/3 stop, I should have a relatively normal exposure;
    1/3 + 1/3 + 1/3 = 1 (normal)

    The cool thing is that you don't have to do the math. Just experiment until you get the right combo to make the image as bright as needed.
  • Average - takes the average of the exposures and creates a finished image
  • Bright - chooses the brightest pixels from each layer and displays those pixels.
  • Dark - chooses the darkest pixels from each sandwiched image and displays those pixels
For the images in this blog post, I used the additive setting. This works well when so much of each image is black. The image will appear to overlap only where there is color.

As you read my process below, don't be deterred by the seemingly complex process. Although I am explaining what I have done, much of the process is still seat-of-the-pants creative photography. My explanation is intended to give you a starting point for your own fun.

Exposure #1
ISO 400  1/40 sec. f/4.5  200mm

(click to enlarge)
For the first image, I wanted a bokeh effect of large, slightly out-of-focus circles. This is usually easy to achieve with a longer telephoto lens like a 200mm, shooting at a low numbered aperture. I made sure that the camera was braced so that the edges of the circles were crisp. 

Two things to note about the Canon camera and multiple exposures. Whatever ISO you use for your first image will be the ISO for all images. Choose carefully, especially in extreme shooting situations like bright sunlight or dark of night. The other feature that is set by the first image is your white balance. 

Here is the second image I made. Note that the Canon camera has the ability to save the base images individually, so you can use them as separate images or play with layers later on in Photoshop or other software. Very useful if you don't quite like your alignment. 
Exposure #2
ISO 400  1/100 sec. f/4  115mm
Here is what the first and second images look like as a multiple. This is the way the camera combined the two images. Note the translucence created by adding the layers together.
First Multiple
Combining Images #1 and #2
After I got a combination I liked, I set about adding third images to the first multiple. One of the beautiful things about the Canon 7D Mark ii is the ability to use the same base image for several multiples. You get a chance to try different techniques, compositions, exposures and combinations. 

Here is my first attempt at a 3rd layer for the multiple. I moved the camera diagonally while shooting to create the movement effect.
Exposure #3
ISO 400  1/4 sec. f/11  150mm
And, here is the first combination again. I like how animated and festive the different sized elements become in the final image.
First Finished image

Since the Canon gives me the opportunity to use one base image for multiple finished compositions, I shot several versions of the final image. Here is another option for a finished image.
Second finished image created with different 3rd exposure

Same first image as above
Combining Images #1 and #2

Exposure #4
ISO 400  1/5 sec. f/11  200mm