Photographing a Small Caterpillar in Challenging Conditions Using an iPhone by Ulick Malone

On Friday April 20, 2018, the day after my final Thursday-night MLA 326 "Nature  through Photography" classroom session, I was out walking in our neighborhood in the Murdock Park area of West San Jose with my wife Pat. As the course had just wrapped up, I was taking a break from photography that day and so was not carrying my Sony camera, though I did have my iPhone 8 Plus in my pocket.

During the off-road-trail part of our walk, Pat noticed and showed me a photography-worthy situation: a small caterpillar was spinning silk thread and was hanging from this thread about six feet above ground. The silk thread was hanging from a branch of a tree above us. In my mind, this scene of the caterpillar suspended in mid-air seemed to demand to be photographed.

According to the Wikipedia Caterpillar page: "Some caterpillars can evade predators by using a silk line and dropping off from branches when disturbed." The caterpillar that Pat and I encountered had this capability to spin a silk thread that it could use to lower itself from the branch of a tree when it wanted to move away from the branch.

Although I was taking a break from photography, I wished that I could photograph this caterpillar and regretted not bringing my camera with me on the walk. There seemed to be no point in going home to get the camera, as it was unlikely that I would still find the caterpillar in his current location when I returned with the camera.

I decided to try and photograph the caterpillar using my iPhone. I was pessimistic about my chances of getting a good photograph of the caterpillar using my iPhone for several reasons. The caterpillar was small, a little less than an inch long. A mild wind was blowing and now the caterpillar was swinging back and forth with a pendulum-like motion. The caterpillar had also reacted to the interest of two humans by starting to climb back up the silk thread and would soon be out of range for photography. A small moving caterpillar did not seem to be a subject that the iPhone's built-in camera app would be able to lock onto for the purpose of automatic focus. My assumption was correct and when I tried to photograph the caterpillar using Apple's built-in camera app, all I got was a very blurry photo of the caterpillar with the trees in the background in focus. The Apple camera app auto-focussed on the background scene, leaving the caterpillar in the foreground completely out of focus. To solve the focus problem, I would need to be able to manually control the focus of the iPhone's camera. Now I really regretted not having my Sony camera with me—that camera has a very nice manual focus user interface.

Apple's built-in camera app on the iPhone does have a basic touch-driven interface for manually controlling focus. This requires touching the object on the phone's screen that needs to be in focus. This feature was inadequate for my immediate need to focus on the caterpillar, since the caterpillar was moving around too fast on my phone's screen, making it impossible to manually focus on the caterpillar using this method.

I was feeling quite determined to solve the manual focus problem on the spot. Just then I remembered that I had a number of third-party camera apps installed on my iPhone (though I had very little practice with any of these apps). I picked an app called Manual to see if it supported manual focus, and I quickly found that it had an intuitive manual focus user interface that was more suited to the task at hand than the manual focus feature of Apple's camera app. I quickly got the hang of the Manual app's manual focus feature, which works like a traditional camera's focus feature and allows continuous adjustment of the distance from the phone that is in focus using a touch-driven "slide interface" (see below for a more detailed explanation of that interface). The swinging motion of the caterpillar still made this photography task challenging, but I was soon able to get a pretty good and reasonably well-focussed shot of the caterpillar suspended in mid-air:

Caterpillar iPhone 8 Plus Photograph by Ulick Malone

ISO 20  6.6mm  f/2.8  1/607

Manual iPhone Camera App Developed by William Wilkinson

This photograph benefitted from the two times optical zoom capability of the iPhone 8 Plus. The version of the photo shown here has been cropped significantly but not to the point where digital artifacts from the cropping process are becoming problematic. The thin vertical silk thread from which the caterpillar hangs is not visible in the photo, with the exception of a tiny white blob near the top of the photo.

This view of the caterpillar appears to be of his "underneath parts"—the part of the caterpillar that would be facing down if he was crawling on the ground. A pair of eyes are visible near where the two antennae connect to his head.

Though I may have been able to get a better caterpillar photograph in this situation with my Sony camera, I am still quite pleased with this iPhone photograph achieved with the help of 2X optical zoom and the manual focus feature of the Manual app. This may not be a great photograph, but individual caterpillar hairs are visible and are reasonably in focus.

The following screen-shot (from the Web page shootmanual.co) shows the user interface of the Manual camera app running on an iPhone:

The manual focus control in the above image is the horizontal row of white dots above the ISO 300 indication. Manual focus can be manipulated by using the touch interface to slide the row of dots to the left or to the right. The current focus adjustment is shown by the position of the small vertical line within the row of dots. I found this to be an easy to use and intuitive interface. I did not have to read the manual to figure out this manual focus method when trying to focus on my caterpillar subject.

This was truly a case where iPhone photography saved the day. Without the iPhone in my pocket, I would not have come away with this nice shot of a caterpillar suspended in mid-air.

- Ulick Malone, April 23, 2018.