The Camerascope Lab
In this lab, you will create a simple, inexpensive microscope with your cameraphone or tablet. Materials and instructions for the lab are provided in a kit, which you can purchase here. Once you create your microscope, you will explore the microscopic world, including visualizing fruit flies, plant guard cells, onion skin cells and even your own cells.
Introduction to Microscopy
Fig. 1. Flea illustrated by Robert Hooke in Micrographia. A simple microscope uses a lens to enlarge a virtual enlarged image of a specimen.
While the origins are uncertain, by 1644 primitive versions of the optical microscope were used to visualize the microscopic world. Over the next several decades, the precision of microscopy improved vastly and began to have a huge impact on our understanding of the natural world. While not the first publication to illustrate this new knowledge, Robert Hooke’s book Micrographia (1665) had a huge impact on the scientific community, due to his impressive illustrations showing immaculate detail of tiny insects, such as the flea (Fig. 1) and ant. Perhaps the biggest breakthrough resulting from early investigations using the microscope was the discovery of microorganisms first reported by Antonie van Leeuwenhoek in 1676. He called these cells animalcules, Latin for “little animals.” Prior to this, the presence of single-celled organisms was completely unknown and his work was met with great skepticism. His first discoveries were of relatively large microorganisms we now call protists, large unicellular organisms with a nucleus. Van Leeuwenhoek never stopped perfecting his microscope. In 1676 he was the first person to identify and describe a bacterium, the smallest of microorganisms.
Fig. 2. Hooke’s microscope.
Today, the most common lab apparatus in a biologist’s tool kit is a compound optical microscope (Fig. 2), which uses several mirrors and a variety of lenses to focus a light source on to the specimen, providing magnification up to a thousand times greater than human vision. A typical compound microscope is cost prohibitive for an online microscopy lab. In this lab, you will construct a simple microscope and utilize your smartphone or tablet to visualize specimens up to one hundred times the power of the human eye.
A simple microscope
A simple microscope uses a single lens to enlarge an object, through angular magnification. A common example is a magnifying glass, which provides the viewer with an enlarged virtual image of a specimen. While compound microscopes are common part of a laboratory toolkit, the advances in optical photography of smartphones and tablets allow curious minds to explore the microscopic world inexpensively and with impressive results.
Lab 1: Making the camerascope
Fig. 3. Set up for the camerascope.
For this lab, you will construct a simple microscope using a single lens (usually found in laser pointers), a bobby pin and a cameraphone or tablet.
The Collimating lens
A collimating lens (Fig. 3) aligns incoming light into parallel rays. It magnifies objects by focusing parallel light rays from a singular focus point, producing an enhanced virtual image. One disadvantage of simple microscopes (those that only use a single lens) is the focal point of the specimen is limited. When you look at your specimens under the camerascope, you will notice the center of the image is sharply focused, whereas the edges of the image are blurry. The typical laboratory utilizes a compound optical microscopes, which minimizes edge blur by synchronizing mirrors and multiple lens, which makes them significantly more expensive.
Once you create your microscope. Turn on your phone and access the camera application. You’ll notice it is blurry.
Fig 4. Proper lighting conditions are essential for microphotography.
Illuminate your light source on your specimen, moving it around to find the best lighting conditions. Photography is all about taking advantage of optimal lighting conditions. This is where you have to be creative. The lens of your microscope will be touching or nearly touching the objects you are visualizing. To create quality images, you will need to explore varying lighting designs. Locate a flashlight (or two) from around the house. Ideally, prop up your lighting setup in a stationary position as close to the object you are visualizing (see fig. 4). Be inventive - use books, binder clips, tape, forks, spoons, knives and the kitchen sink if you need to. It is useful to have an additional person to be able to hold and manipulate an additional light source as well. Alternatively, you can visualize your set up in a sunny window or even outside.
Place the lens very close to the specimen and you will be able to see approximately 50x-100 your normal vision. Take photos. You will benefit from post-processing your images. There are many free apps that provide powerful modifying capabilities for visualizing your imagery. Explore and experiment. We recommend the trying out some of the following: VSCO cam, Flickr, and yes, even Instagram.
Explore your world. If you take images with your camerascope that you are proud of email your images and descriptions to thebiologyprimer@gmail.com to be considered for inclusion in the curated camerascope gallery.
Lab 2: Exploring the scale of your microscope
Now that you are a pro at microphotography, discover the scale at which are are visualizing your specimens with the particular microscope set up. In the print version, you will compare several examples of the letter ‘e’ at different font sizes (size 4-14) in Times New Roman and illustrate them. Once you acquire an everyday concept of the scale of your camerascope, you will measure the scale by photographing a ruler and calculating the magnification power. Also in the print version of this lab, there is a secret word printed at font size 4, which can not be read with the naked eye but can be read with your camerascope.
Lab 3: Greyscale
In the print version of the lab, you will analyze how printers display variant shades of grey on paper by a process known as dithering black ink in specific patterns.
Lab 4: Fruit Fly
The fruit fly (Drosophila melanogster) is one of the most studied organisms in biology. A preserved fruit fly is included in your kit. Using your camerascope and lighting setup, you will photograph and illustrate your fruit fly’s eye (Fig. 5)
Fig. 5. Closeup of a fruit fly’s eye.
Lab 5: Guard Cells
In order to undergo photosynthesis, cells inside a leaf must acquire water and gaseous carbon dioxide. Water diffuses up from the roots. To conserve water, the exterior of plant’s leaves are coated with a watertight, and subsequently airtight, waxy layer known as a cuticle. Land plants evolved specialized cells, known as guard cells, that open and close allowing carbon dioxide to diffuse into the leaf. Plants conserve water by closing their guard cells, but must open them to acquire carbon dioxide. In this lab, you will use your camerascope to visualize the guard cells of a green onion. Leaves from many other species of plants should work equally well.
Below is a video of how to make a wet mount of the green onion epidermal cells highlighting the guard cells.
Lab 6: Onion Skin Cells
The skin (epidermis) between the dormant leaves of an regular onion are a single cell thick, and serve as a great representation of the internal structure of plant cells. Below is a video of how to make a wet mount of yellow onion skin cells.
Lab 7: Human Cheek Cells
Fig. 5. Human cheek cells.
Now, look at your own skin cells. In this lab, you will swab the inside of your cheek exfoliating dead skin cells and stain them to visualize the nucleus. Don’t worry, we are constantly sloughing off skin cells. On average your outer layer of skin is completely regenerated every 10-14 days. Note: skin cells are much smaller than the plant cells you visualized previously.