A Buyers Guide to Compound Microscopes for Mycology

Part 1

© Peter G. Werner

Original publication: Mycena News, April 2008

For those of us who have gotten into the study of mycology beyond the simple Can I eat it? level, identifying mushrooms to species (or maybe even noting previously undescribed species) often comes down to noting differences in the fine anatomy of the mushroom. And many of these fine features cannot be seen without the aid of a microscope.

There are many serious amateur mycologists who would likely be interested in learning mycology on this level, but balk at it because of the perception that a microscoperequires the investment of many thousands of dollars. To many peoples surprise, its actually quite possible to buy a good light microscope for well under $1,000. While a microscope is a somewhat expensive investment, it is no more expensive than buying a good set of camera equipment.

However, like investing in camera equipment, it really helps to know what youre buying. To that end, following my previous set of articles on camera equipment, Im contributing a couple of articles that will hopefully demystify microscopes for those considering buying one.

Compound and Stereo Microscopes

The first issue that needs to be discussed is whether one wants a compound or stereo microscope, or both. A compound scope is probably what most people think of when they picture a microscope. This is a microscope where you view a highly magnified image of a thin object mounted on a slide, with light that is transmitted through the image. Many will also be familiar with stereo scopes (aka dissecting scopes). These are microscopes where a larger object is viewed in three dimensions using light reflected from the surface of the object (though stereo scopes are usually also capable of transmitted light illumination), typically at magnifications lower than those found on a compound scope.

As to what one needs for mushroom ID, I recommend having both. A good stereoscope can help one see the surface features of a mushroom in much finer detail and is also helpful to have for specimen preparation for a compound scope. However, if one has to choose just one, Id say get a compound scope. The features you can see with a stereo scope can also generally be seen (albeit with more difficulty) with a good hand lens; however, theres no substitute for a compound scope for viewing features like spores, cystidia, etc.

Because of space limitations, the rest of this article will be on the features of compound scopes. At some point in the near future, Ill contribute a compound scope buying guide, which really deserves an article in and of itself.

New vs. Used

If one has $400800 to spend on a microscope, you can go either of two ways. You can buy a brand new scope from a source like Microscope- Depot.com, which will probably be a generic Chinese-made scope, or an older used scope of a high-quality make like Zeiss or Nikon. There are pros and cons for each. New scopes will be clean and without risk of prior wear-and-tear. However, no-name Chinese scopes are not manufactured to as high of quality-control standards as the better-known name brands and may come with built-in problems. If you buy from a reputable dealer and the scope is warrantied, you should be able return a bad scope for repair or exchange. Another problem is that only a minority of generic Chinese scopes (typically the more expensive ones in that range) come with Köhler illumination systems, a feature I feel is essential in a good compound scope.

Older (circa 1960s1980s or even older) compound scopes from high-end manufacturers, like old quality cameras, hold up well over time and are the workhorses of many university mycology labs to this day. The downside of buying these is that one usually doesnt know the history of these scopes and whether theyve been used carefully or abused. One can buy used scopes from professional microscope dealerships with a solid maintenance history; however, one will typically pay two or three times as much for a scope from this source (probably in the $15002000 range) than one would from a source like eBay or Craigslist. (In some cases, eBay scopes are sold by microscope specialists who clean and refurbish the scope; this is a valuable perk in a used scope when available.) I think Köhler illumination is essential both for getting even illumination and, more importantly, for limiting stray light that actually can interfere with getting the full resolution possible from your optical system. A scope thats capable of Köhler illumination should have two essential components. One is an Abbe-type (or even better aplanatic or achromatic) condenser that includes a movable diaphragm, a carrier that can be raised and lowered, and centering screws or some other kind of centering mechanism. The other is a movable field diaphragm located somewhere adjacent to the light source itself.

Buying a Used Microscope

If one does decide to go the used route, ideally one should be able to see the scope before deciding to purchase it. However, since most such scopes will probably be found over eBay or through some other mail-order source, this may not be possible. Therefore, make sure your scope has a return guarantee, preferably without strings attached.

When evaluating a scope, the first thing to look for is whether the scope and its components are more or less clean, especially the lenses. If there is dust or dirt, is it extensive? Are any lenses or other components delaminating or otherwise loose? And if there is dust or dirt, is it found merely on the outer components (which are cleanable) or in internal components, where it may not be possible to get to?

First, try setting up the scope for Köhler illumination (see the link I give later on how to do this) and make sure it is possible to do so, up to the highest magnification. The objectives and the condenser should be able to focus properly and the optical components should be alignable. One should look at all of the objectives both in and out of focus to see if there is dirt in the light path. Remove the objective and eyepiece lenses and the condenser and examine the lenses individually for dirt and delamination.

Even if the scope is clean and in good shape, if you buy a used scope without a history of either regular maintenance or refurbishment, one should consider taking the scope to a microscope service for cleaning and alignment. This will probably run $100200 and should be considered in the cost of buying a used scope. (I provide a list of Bay Area services in the links I provide after the article.)

Brands

Based on overall build quality and the availability of Köhler illumination features, Im pretty partial to used high-end scopes. The best are ones made by the big four manufacturers (Zeiss, Leitz/Leica, Nikon, and Olympus) or the excellent microscopes once made by the now-defunct Wild Heerbrugg. There are also a number of second tier manufacturers (many also now-defunct or merged into larger companies), notably Reichert, American Optical, Meiji, Lomo, and Vickers, that many people swear by, even if they dont have quite the reputation of the top-tier companies.

(Also, some clarification is needed concerning Zeiss, because during the Cold War there were actually two Carl Zeiss companies, a situation Ill explain more about in the link to my blog, provided below.)

Of course, as with cameras, the quality of the scopes by each maker varies considerably between models, and all of the major manufactures made lines of simple student scopes that are generally not capable of Köhler illumination and are not generally research quality. Lines of quality compound scope that I often see selling on eBay for good prices (often under $600) include the Zeiss Standard (which is what I have), Nikon Labophot, Reichert Microstar IV, and Meiji ML2000. American Optical 110 scopes are also good, though one must be cautious with these, as a disproportionate number of old AO scopes have ended up as door stop scopes in various university departments and Ive seen some extremely dirty and abusedlooking ones go up for sale.

In part 2, Ill go into more detail about microscope components to look for, either as components of the system youre buying, or as upgrades. And since there is more useful information and links than I can provide on this subject here, I refer the reader to the following link on my new mycology blog: