March 22, 2020,
Have you tried macro photography with a light table? It’s a great way to explore and enhance your photography skills while cooped up in quarantine.
Did I hear you say “I don’t have a light table!” I bet you do!
An iPad or any other computer tablet will make a great light table. I use an app on my iPad called Trace Table. It’s almost free–it cost me $0.99. There are free apps that will work but I bought Trace Table because it has features for tracing and transferring hand drawings to digital drawings which I use in my artwork.
Last night I used my Canon 80D DSLR camera with my Canon 60mm macro lens to shoot a bunch of macro photography shots using my iPad as a light table. I used my good tripod where the center post can swing out and form a horizontal boom. Here is an iPhone photo of my setup.
Since the camera is mounted on a horizontal boom, I find it very convenient to use the focusing rail. Without the focusing rail, one would need to adjust the length of the three tripod legs everytime one wants to move the camera up or down a little bit. With macro photography, one likes to adjust the camera’s height often! My focusing rail is Velbon’s “Super Mag Slider” and it allows me to adjust in two dimensions–up and down and side to side. For macro work, you could easily get by with a less expensive focusing rail that adjusts only in one dimension–up and down. Here is a close up of the focusing rail with its two knobs for adjusting in the two dimensions.
Since I want high quality, I shot at an ISO of 100. To maximize the depth of field, I set the camera’s aperture at f/22. I used manual focusing. You might be tempted to shoot the camera set at Aperture Priority (Av on Canon) but don’t! If you do, you get a shot like the following:
On Aperture Priority, the camera’s metering system will read the strong light of the iPad and your subject will be in silhouette. Great if you want a silhouette! You want to set the camera to M (Manual), You adjust the shutter’s time manually until you can capture the light that is coming through the subject, for example, as shown in the next image of a similar flower cluster.
Note the following interesting fact: with the long exposure time in the above image, the white background is still just white, even though I blasted the highlights in the second image to the extreme. This is an important fact to understand when using high key lighting, i.e., white background. Highly overexposed white is still white!
As you can see, the iPad as a light table is great source of light for objects that are translucent, such as an orange slice, a flower, or a bug. Many of us knew that! However, you may not have realized the following use. It can make solid objects look like they are floating in the air! What?? Look at the following image of a cat toy (Used with Gandalf’s permission).
For the cat toy shot, I used a different set up. Rather than shoot straight down on the object lying on the iPad, I moved the camera off to the side and turned on the overhead ceiling light, The cat toy was lying on the iPad that was still lying flat on the dining room table. Because our brain expects the light to come from above as in the sky and expects to have shadows near the bottom of an object, the cat toy appears to float in midair! Any shadows from the above ceiling lamp are canceled by the strong light of the iPad underneath. If you look closely, you can see the temperature of the light on top of the cat toy is slightly warmer (more yellow) than underneath. I made no attempt to balance the temperature or intensity of the ceiling light to the iPad.
Same setup as the cat toy before but with a Matchbox toy car. It looks like it’s flying through the air tumbling.
With a bit of creativity, your iPod as a light table can help you create many interesting macro photographs. Have fun!
Stay safe and healthy. Use the extra time you have to improve your photography skills. 
Dan
