Often a readily accessible photographic record is desirable in the case of a new kernel phenotype or for the precise phenotype of a kernel that gives rise to a plant destined for molecular analysis. Due to the large number of mutants that we handle and the increasing use of our material for molecular analysis we found it necessary to develop a photographic system in our lab (versus use of campus facilities). In doing this we have developed a system that is easy to use, that results in high-quality slides, and for which the investment in equipment is very low. We believe the system developed in our lab is significant enough to be explained in detail in the following text.

The equipment required is dependent on what you already have in the lab. A zoom-stereo microscope is desirable because it allows for easy framing of the kernel. A trinocular microscope is not necessary if the eye tube diameter is less than 29mm, in some instances it may be necessary to remove the focusing ring for the left objective to achieve this maximum tube size (minimum tube size is 23mm). The Minolta X570 camera system is the only system available that can be used on eye tubes larger than 25mm and most eye tubes on stereo microscopes are larger than 25mm. The light source needs to have the capacity to produce an intense narrow beam. A fiber optic illuminator or an old external light source for a compound microscope are possible light sources with the fiber optic being the best choice. Polarizing filters are needed for the light source and microscope to decrease the amount of glare produced from the kernel. If a filter is not available for your microscope the best alternative is a camera filter; this will preserve the resolution. Cheaper plastic polarizing film can be used on the light source. The 35mm camera is attached to the microscope via the photo tube and the round microscope stage plate is replaced by three unattached microscope slides in an H formation.

To take a photograph the kernel is placed on a small piece of clay, the clay placed so as not to be visible in the photograph. The use of the slides allows for easy movement of the kernel and will help prevent shadows appearing in the picture. A black velvet cloth or other desirable background color is placed under the microscope stage. The cloth must be at least one inch from the slide, allowing the kernel's shadows to fall out of the focusing plane. The light is then concentrated on the kernel. If the light source is from one direction, a small piece of paper is needed on the opposite side of the kernel to reflect light onto the dark side. A bidirectional light source does not need the paper, but it poses a new problem in that the kernel's reflection will appear on one side of the picture. To overcome this the horizontal leg of the H formation on the opposite side of the reflection must be raised enough to eliminate the reflection as seen in the viewing frame. The magnification of the microscope is adjusted so that the desired amount of frame or specific section of the kernel is showing. Looking through the camera, the polarizing filter is adjusted to remove the glare, and the picture is taken using a cable release while at the same time covering the camera eye piece. Using the Minolta system the camera can be set on automatic, thus preventing the need to take a series of bracket shots to determine the shutter speed. If the ASA of the film is greater than 50 it may be desirable to set the camera at half the normal ASA for a greater depth of field. Other suggestions are: (1) Use an imprinting device to put an identificaion number on the picture for easy record keeping; (2) Do the photography in the dark; (3) The slower the ASA the greater depth of field. We use Kodak Professional 50 ASA Tungsten Ektachrome (EPY 135-36) for colored slides. Our equipment is as follows:
 

Camera body	Minolta X570	$149.95
Imprinter	Minolta Quartz Data back I	89.95
Photo tube	Minolta Microscope Adapter II	29.95
Polarizing filters	Promaster	20.00
	TOTAL COST	289.85

Brian E. Scheffler and Peter A. Peterson
 
 

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