Cross-Polarized Lime

This is another entry in The Daily Post Photo Challenge: Experimental.

We have been experimenting with macro photography of readily-available fruit. One technique we wanted to try was using cross-polarized light. Generally, light scatters in all directions. A polarizer filters light so that only streams of light in parallel planes pass. Theses filters are used in photography to eliminate reflective glare and improve contrast.

Two polarizing filters can be arranged in sequence with light passing through the first filter and the camera lens behind the second. These filters can be rotated to block all (really almost all) light. If a translucent object is placed between the filters, it can scatter some of the incoming light. Different regions in the object can scatter the light to different degrees. Some of the scattered light is aligned with the second filter and is visible to the camera. Whew!

We placed a thin lime slice (a.k.a a translucent object) between the first filter illuminated by a light table and the second filter attached to the lens of a tripod-mounted camera. The first filter was mounted in a hole cut in black poster board to prevent other, non-polarized light from leaking through and reaching the camera. The filter on the lens was then rotated to maximize the contrast in the image. The following image shows the result.

The dark regions show where the light passed through the lime without having its polarization changed by scattering. The bright regions show where the polarized light was scattered as it passed through the lime and much of this scattered light aligned with the second filter mounted on the lens. This was a fun way to pass a chilly grey day at home.

This photo was taken on November 19, 2017. Specs are:

Canon 100D, ISO 100, f/8, 0.4 sec, 100 mm

Raspberry

This is our entry in The Daily Post Photo Challenge: Experimental.

The following  macro photograph shows the results of an experiment in which a red raspberry was illuminated from the inside.  A sheet of black paper with a small hole was placed on a light table to provide the light source and the berry was centered on the hole. The berry was only about 1/2″ across but the image looks like an exploding star to us.

This photo was taken on November 17, 2017. Specs are:

Canon 100D, ISO 100, f/16, 30 sec, 100 mm

Water Drop Photography

We are starting to develop some control in photographing water drop collisions. The photos below were created using an ancient 100 mm macro lens mounted on a Canon 100D affixed to a tabletop tripod. A 2 to 5 second exposure was made in a darkened room while two successive drops were released into a martini glass filled with water. A flash (at 1/16 power) was triggered as the drops collided.  In the “umbrella” shape seen in the photos, the “shaft” is created as the first drop plunges into the water in the glass and then rebounds into the air. The “canopy” is created when the second drop collides with the rebounding first drop.

UPDATE

In response to a question we received, we are adding some additional technical details. First, the backgrounds are simply random objects we thought would be interesting. The background in the featured photo is a cloth apron. The other picture backgrounds are simply patterned papers we bought at a craft store. It really doesn’t matter much what one uses so long as it involves small scale random patterns and good color contrast. The narrow depth of field of the 100 mm macro lens helps blur the backgrounds so the focus of the pictures remains on the water drops. We think there are patterns on the internet that can be downloaded and printed that would be equally useful. Here is an additional photo in which a sheet of paper covered in blue glitter was used as a background.

iBallRTW-Water Drops-1

A second point is that the flash was aimed half way between the water drops and the background. If the flash directly hits the water drops, they will become nearly invisible. The angle we used reflects the light through the drops and causes highlights because the drops act as lenses bending the light and sending some of the flash towards the camera. The lens effect is especially apparent in the photos with nearly spherical water drops where the background is inverted and reversed from left to right within the drops.

A final point is that focus is critical for good shots. We switched our lens to manual focus and one of us held a pencil tip on the water at the point of impact of the water drops while the other focused. Since the Canon 100D has live view, we first focused at 1x and then 5x and 10x to make sure our shots would be sharp.

We are still learning how to make these photos but would be happy to answer any questions we can.

Playing with water drops

We like to find patterns. For a little diversion, we decided to photograph water drops to see what patterns we could find. (We did that in earlier posts, too. See A little diversion: high-speed photography and Another Diversion: Macro Photography ). The technique we used is described by Gavin Hoey  on YouTube (//www.youtube.com/watch?v=fwExpFDUC9Y) and it produced the following photos. We labeled the photographs with what we thought we saw when we looked at them. If you want to suggest something else, please leave a comment.

Splash-2
The Elephant
Splash-10
The Basketball Player
Splash-9
The Embrace
Splash-8
Nixon
Splash-7
Trix Rabbit
Splash-5
My Cup Runneth Over
Splash-4
Mother and Child
Splash-3
The Snail
The Turtle
The Turtle

Another Diversion: Macro Photography

We are still in photography class instead of travelling. This week, we worked with extensions tubes to use normal zoom lenses for macro work. We took some interesting pictures of liquid drops. Two of them are shown here. These pictures capture milk being added to coffee. We call the first E.T. and the second The Wizard.

iballrtw_161121_4408iballrtw_161121_4402