Selection and Use of a Microscope for Aquarists, by Bob Blaho

Selection and Use of a Microscope for Aquarists

by Bob Blaho
from The Informer, Green Water Aquarist Society of Chicagoland, May 2003
Aquarticles

The first thought that pops into many readers’ minds may be, “why bother?” This is exactly the intent of this article. We hope to establish for you, whether you have or might have a need for use of such an instrument. We’ll establish what your choices of microscopes are, how they function, and what purpose you, as an aquarist, may have for this tool. Some of this material is a compilation from various sources and some is based on personal experience. Specific sources are listed at the end of this article.

First, what is available out there? The answer to that question is another question. What do you need to accomplish? If you’re looking to gather more information about your aquarium environment, this is one way to do it. Visual information can provide us with facts that we can respond to. The first thing most of us do when we walk into a room, which has one or more aquariums, is to take a closer look at them. To look at what types of fish are in the tanks, what types of plants are planted, and the condition of the fish, plants, or water. In other words, what can we see! Our limit, to what we can see, is our eye. We frequently aid (especially as we get older) our eyes with prescription glasses or magnifying glasses. Those of us that do extremely fine detail work use a loupe or binocular magnifier. These are the instruments that are simple, inexpensive, and usually easy to use. They let us take that closer look to get the information we’re after. The lenses we use to see and identify what we’re looking at, come in a variety of choices. Selection of your lens type is usually determined by the level of magnification needed to accomplish your job. As the magnification and quality level rise, so does the cost. Each level of capability satisfies its purpose. The microscope, the compound optical version, is only a lens design to help us see items closer up. Its capability for magnification covers the range of 20-1000X. The electron microscope versions which go beyond 1000X will not be discussed. The compound light microscope then is what we’re concentrating on. It answers the question, “why bother?” If you have the desire to take a closer look at this aquatic environment, a need to identify what might not be normally visible, then you probably would benefit from using a microscope.

Selection of your microscope will again be based on your individual needs. The toy versions for children are probably the reason that many people don’t proceed further. Any optical instrument is only as good as the precision and quality of the glass it uses. A microscope should be a lifetime investment. Buy the best you can afford to do the job you want or may want to do. Look for the magnification range you need in selecting your eyepieces and objectives. Stick with those models that conform to one of the best recognized standard configurations. These are the Deutsche Industrie Norm (DIN), most common, or Japanese Standard (JIS). Stick with DIN standard components and you’ll have the best of all worlds. This will enable you to select a greater variety of components for your microscope that will be interchangeable and expand your capabilities. A typical compound microscope consists of these basic components: eyepiece(ocular), tube, objective, stage, stand, condenser, and light source. Look at a drawing or photo of a typical compound microscope and you will have no problem in identifying these parts.

microscope.JPG (65488 bytes)

Presented is a Carl Zeiss Standard model trinocular microscope. Viewing the image is somewhat self explanatory. The double eyepieces, side by side, provide a binocular view and the third ocular provides a monocular view for either another viewer or photography, hence the trinocular label. The objectives are mounted on a turret that holds up to five objective lenses that normally provide differing magnifications that are selected by moving the turret to the desired lens. The tube in this case is provided through optical means and the stage is the part that holds the microscope slide, in this case, held in place by a movable slide adjuster mounted on the stage. The condenser is just below the stage and the light source can be seen at the bottom right rear of the stand. There also is a choice in variety for each of these items. Eyepieces can be monocular, binocular, or trinocular versions. The monocular variety is the least expensive, since it uses only one eyepiece. The types of eyepieces can be Huygenian, Ramsden, Kellner, and Periplan. Each succeeding class of optics increases in quality and cost. Objectives also are available in the degree of optical correction available. These are achromatic, semi-plan, and planar. Achromatic objectives provide a flat field of view in about 65% of the center of the image and are most common. Ramsden eyepieces, often called Wide-Field, are usually used with the achromatic objectives at higher power. A look at a catalog listing selection will quickly establish what you wish or need to afford. The best way to go, is to buy a microscope that comes as a system, so you can expand your choices later. An eyepiece in 10X Wide- Field and turret arrangement with your selection of objectives in 4X, 10X, 40X, and 100X will get you started for most purposes. This gives you the capability of 40X, 100X, 400X, and 1000X. Most of your aquarium work will be done between 40X and 400X. 1000X(oil immersion) is used for more advanced cellular and bacterial work. The stage of your microscope can be plain with spring clips to hold your glass slide or have a mechanical stage that adjusts for the short distances a slide is normally moved. For bright field illumination, the light source can be external, using a mirror to direct the light to the slide, or be built into the base to provide illumination. With either light arrangement, alternate types of lighting may be desired. This could be the basis of another article in itself. The question is, at this point, what should one consider as the basic minimum setup?
Consider these points:

1 - Make sure that the microscope has a solid stand, with fine and coarse focusing and a monocular tube.

2 - The eyepiece should be 10X to start, with a selection of 5X, 15X, and 20X oculars added as needed.

3 - A turret holding at least three objectives, achromatic in 4X, 10X, and 40X will be sufficient to start.

4 - The stage can be equipped with only removable spring clips or have a mechanical stage to allow more precise placement of the slide. Removable mechanical stages can be added later if desired. This option starts at about $70.00 and goes up in price based on capabilities.

5 - A light source, such as a microscope lamp or even a simple high intensity desk lamp, unless the illumination is built in.

6 - Beneath the stage should be a condenser lense that can be focused to properly illuminate the slide. A diaphragm to control light intensity and a filter holder should be part of this package.

A basic package for the above, new from a catalog or outlet, will start at about $200.00 and go up in cost based on quality, choice of lenses, and other options. A good used microscope can be found around college campuses and in papers like the “Trading Times” and at on-line auctions like eBay. This would enable you to buy a better quality instrument at the same or lower cost than a new one. Going up in price range will obtain a binocular, four objective turret, a mechanical stage with built-in illumination, microscope starting at about $500.00 used. A good quality microscope of this variety, brand new, will start at about $800.00 and rapidly escalate based on optics and brand name. Brand names like AO(American Optical), B&L(Bausch & Lomb), and Spencer are American brands, with Zeiss, Leitz, and Wild being European. Japanese brands like Nikon, Olympus, Myoda are popular and sometimes will cost less than the European brands. Russian optics are another source of decent quality and are usually priced right. Look for a system that will allow you to expand your capabilities and hold its value, should you decide to sell.

So now that you’ve selected what you think is the best microscope for you, what do you do with it? You will have to use it and acquire some experience in developing your techniques. Books and manuals are available in most libraries covering just about all aspects of microscopy you may want to learn. Concentrate on developing your basic skills. Use your microscope for checking the quality of water, identify the microscopic plants and creatures that inhabit your aquarium along with your fish. If you have baby fish, which require live food, check for paramecia, rotifers, daphnia, and other micro food cultures in your aquaria. Keep tabs on how the cultures are doing. See what other helpful or detrimental organisms are present. Do you keep egg layers? Pluck an egg and put it under your lens to see if it is fertile. If you see no life(movement) in the egg, it is not fertile. Then just continue with your process of elimination to establish what caused the infertility. Do you have health problems with your fish, plants, or snails? Check to see what’s different with the healthy versus the unhealthy. Identify your problem hosts so you can take a targeted approach to correcting your situation. The books below can give you more ideas on use of your microscope.

Several books you may want to look at are as follows:
- Using the Microscope - A Guide for Naturalists by Eric V. Grave, Dover Publications, 1984
- Hunting with the Microscope by Gaylord Johnson and Maurice Bleifeld, Arco Publishing, 1980 3rd ed.
- Diseases of Aquarium Fish by Robert Goldstein, T.F.H. Publications, 1971
- Handbook of Fish Diseases by Dieter Untergasser, T.F.H. Publications, 1989
- Discus Health by Dieter Untergasser, T.F.H. Publications, 1991
- 2003 Optics and Optical Instruments Catalog, Edmund Scientific

These sources will help you develop your techniques and aid in identifying what you’re looking at. As you gain experience, you’ll add to your library those periodicals that cover your areas of interest. The knowledge you gain can be useful not only in your hobby as an aquarist, but also in any other areas where you want to take a closer look at your environment.