Tuesday, July 16, 2013

Making things visible under a microscope requires the creation of contrast

Making pictures using a light microscope has been such great fun for decades.  I had my first serious experiences with a microscope in a histology class at Bradley University in 1976.   I was always struck by the organization, structure and shape of the subjects I was examining. I still have some primitive drawings from that class that I used to help learn to discriminate muscle cells from connective tissue.

Photographing at a microscope can be interesting and every subject has unique and interesting challenges, no matter how mundane. Certainly more complicated samples are more difficult to image but someone once told me, "it is just as much work to make a bad picture as it is to make a good one. Truer words have never been spoken.

The first thing that happens when you sit down to use a microscope is a basic orientation problem. A microscope produces circular images and the field of view is limited. It is almost like using blinders. Most of the field of view will be out of focus and it may also have illumination problems. A user must by adjust the focus and other instrument controls to form an image. Once the image and its structure has been created, subtle controls can then be adjusted to increase the quality of the image. This is required before any level serious investigation can begin. Quality often is described as contrast, visibility, uniformity of illumination. It also might include composition and effective subject isolation.
To locate specific structures often requires careful scrutiny of a subject to differentiate the important structures from the sample as a whole. When a sample is magnified 1000x, a 1" dimension becomes nearly 85 feet. Imagine scouring an area nearly 85 feet in length and looking for a "thing" that is only 1 inch in size. It is time consuming and requires significant concentration.  When photographing for science, the goals of the photography are very clear. The picture needs to contain the required information.

The following photomicrographs contain a fiber in a debris field of liquid and chemicals. There is no real purpose for the photographs except the object seemed interesting to me when evaluated using magnification.

The first photograph immediately below is the fiber at x25. It has been formed using Kohler illumination. The aperture diaphragm or the microscope's steering wheel of radiated energy was established to maximize image resolution. The aperture diaphragm in a microscope control's four attributes of an image, contrast, resolution, range of focus and intensity. It should never be used for brightness control.   The remaining photographs will be described beneath each.

An image Fiber is revealed in a liquid using brightfield illumination with an almost wide open aperture. Structure, contrast and image visibility is low. The image resolution surprisingly is high. In summary, the image visibility is low due to low contrast.

In this photograph, the fiber's image is much more revealed in a liquid using brightfield illumination and with a closed aperture. Structure, contrast and image visibility is very pronounced however the image's resolution has now been reduced. In summary, this image's visibility is high due to high image contrast. Fine structural detail has been lost been so visibility could been gained. Maximizing image detail is a balance of contrast, resolution and range of focus. An operator often can have two of the three, but not all.

To make more contrast, the fiber was photographed in a polarized light system and anything that is not birefringent is not visible and its transmission has been eliminated. The fiber is now easily visible but environment has been subtracted.

Adding a quartz wedge to polarizing light microscope created this result. Amazing.....

Monday, July 15, 2013

Kodak and the Scientific Imaging Group

Kodak as a company is a mere shadow of itself. Time and the evolution to new technology has not been kind to this iconic company.

In its hey day, Kodak had a group dedicated to everything. The Pro market, the science market, the education market, the photofinishing group and so many others. During the course of the next few months, I will be researching and writing about my favorite Kodak products and inventions from the last 30 years.

One very special product was Photomicrography Color Film . Its spectral sensitivity was tuned specifically for increased red and blue response. It also had an increased resolution when compared to similar color E-4 emulsions

Cassini project creates a unique opportunity

I have reposted this because it is fascinating to me. Maybe you will think so, too.

Dear Friends and Colleagues,
As you already know, in only a week's time, our cameras on Cassini will
be turning Earthward to take images of us and our planet alongside
Saturn and its rings.  I have been encouraging everyone to take
advantage of this special event and, at the appropriate time on July 19,
gather outside with friends and family, acknowledge the interplanetary
salute between robot and maker that this opportunity represents, and
consider the uniqueness of our planet and the life on it.  They are all
reasons for celebration, and I certainly hope you all do just that ...

This event has received considerable attention so far ....

     .  from the TED folks:
     . from Richard Branson:
     . from Robert Krulwich of NPR:

But I also want to remind you of two contests that Diamond Sky
Productions, LLC is running in association with the July 19 event.

We will be choosing the best original contributions submitted by members
of the pubic -- an image in one case and a musical composition in
another --  to a Message to the Milky Way that will be beamed in about a
year from the most powerful radio telescope on Earth, the Areceibo dish
in Puerto Rico, in a long-distance call to our fellow galactic citizens.

I hope you can help spread the word far and wide, in any way you can ...
email, Twitter, FaceBook, whatever ... that these contests are a
serious, exciting, and meaningful way to participate in the event, that
the winning submissions will be beamed to the galaxy, and that the first
contest begins next Friday when the image representative of Planet Earth
must be taken.

For more information such as contest rules and submission requirements,
and to check out the impressive list of individuals advising this
Project, you can start at ...

For the times on July 19 when the Earth images will be acquired and
instructions on how to convert to your local time, check out this page:

And come next Friday, don't forget to smile.

Best to all of you!
Carolyn Porco
CEO/President, Diamond Sky Productions, LLC
Boulder, CO

Saturday, July 13, 2013

Its all about the Lighting

Making interesting light is critical to making great photographs. Light and lighting can make or break an image's effectiveness. The illustration shared below is from my Applications of Science Photography class. It was made by one of the sophomores as part of an assignment we give at RIT. These 3 photographs are a classic example of how light and lighting can make something appear differently. I would ask which lighting is the best? and the answer of course is, "it depends."

That being shared, pictured below is an example of Sordoria fimicola photographed using brightfield illumination and dark field illumination at a camera capture magnification of x8. The spores appear very different using these 2 very different illuminations.

Snowflakes are transparent and have many internal facets. As such, when I light snowflakes I try to emphasize subtle features and use small illumination sources from various angles or directions. Just having a bright light will not be adequate to reveal, but rather the creation of good lighting takes time and critical observation of structure.

The precision of the science photograph

I am sure everyone who is a photographer can share the time they became serious about photography. I  can recall that time. I was 17 years old, bought a Minolta SRT 101 camera and I loved making pictures of people. I made the following photograph of the Jackson Twins,  Utica, New York in 1975.

I did not begin making science photographs until possibly 1976. When I was taking a histology class at Bradley University, I had to draw my observations from the class and - like most - my illustrative skills were somewhat primitive. But I managed.

Since that time I have become significantly better at my photography using a microscope. Below is a photograph made in Stockholm October 2012 of camel skin showing the hair follicles as well as sebaceous glands.

Recently I was exposed to Dr Ramon Cajal, a neurologist who practiced in the late 1880's. He was truly a gifted artist.

This next drawing is even more impressive.

Lens aperture, zone of focus and focal length relationships

Photography is some what unique in that it can be defined by its application, equipment or user. Film photography, wedding photography or photojournalist would be examples of this. Photography also has undergone an enormous transformation from Analog [film] technology to digital beginning in 1990 when the Apple QuickTake was released. In 1994 I began making serious photographs using digital cameras and the process was very cumbersome. RIT purchased a Kodak DCS 460 camera for $28,000 in 1997. It had 1600 pixels I seem to recall. It was very exciting and complicated with SCSI addresses and centronix ports, etc.

One thing that has not changed during this transitions is the physics and process for using optics and apertures effectively. Many practitioners of science photography are misinformed about the role of aperture and focal length in the creation of the zone of focus or depth of field. The following is an example I made reproducing the seminal work of Henry Lou Gibson in which the zone of focus using a 60mm, 100mm and 200mm lens does not change when compared other images produced with a similar aperture across the lenses. What does change is the working distance - the distance between the object and the lens.