Topical Tips 4

contributed by Chuck Huck, USA

 

Editor's note: I'm sure we've all acquired tips, techniques, 'tricks of the trade' or perhaps made simple gadgets while pursuing the fascinating hobby of amateur microscopy. Why not share some of yours with us? I'm sure they'll be of interest to others who may not have come across them. Just send us a short note in an e-mail (contact in footer), enclosing a scanned picture or drawing if you wish and we would be pleased to compile, upload and acknowledge your contributions.


 
 

Observing pond-life: Pond collections containing water fleas, cyclops and other multicellular life can be observed in a rectangular glass or plastic container that is narrow, such as a 'Ti-Tac' mint container (shown right). The use of a 10X or 15X magnifier reveals a great deal but use a 5X to 7X magnifier for a more "general" view.

Another method of observation is to use a Petri dish or something similar and use a stereo microscope (20X) to observe your collected specimens.

When collecting from ponds, be sure to obtain some of the algae or other pondweed if present. Much water life clings to this material.
 
 

Containers to keep bits and pieces for microscopy: Microscope slides, cover slips, test tubes, jars, forceps, pipettes, magnifiers and other assorted lab supplies can all be kept handy in one container. I use a 'Plano' fishing tackle box. (Plano is a company that manufactures plastic containers and well constructed tackle boxes; it is located several miles west of my home in the town of Plano, Illinois.) The tackle box has an open area on top with a hinged lid. Beneath that are about four pull-out drawers that can hold smaller items. Larger items are stored in the top of the boxmounting fluids, microscope slide boxes, magnifiers, extra objectives or eyepieces and assorted sundries. The small plastic toolboxes (shown right can also be used).
 
 

Multi-coloured microscopy: For viewing objects such as certain crystals under polarized light, cut a disc from a piece of Polaroid material and place on top of the microscope light source (if in-built), or over the mirror if an external light source. Then cut a disc from the Polaroid material that will fit inside the ocular. Just unscrew the ocular and place the material inside so it fits tight up against the stop. I use a separate wide-field 10X ocular for this so it is always ready for polarization use. By turning the ocular, you achieve various effects with polarization. Works great. (Editor's note: A cheap source of Polaroid filters are the plastic clip-on Polaroid sunglasses for spectacles; shown right. If preferred, the filter can be placed on top of the eyepiece held in place with e.g. a tiny piece of Plasticene. This places less than optically perfect filters out of the plane of focus and also avoids the need for the filter to be scrupuluously dust free.)
 
 

Darkfield without a condenser: Darkfield is a fascinating way to observe objects such as pond life, diatoms, crystals, insect parts, etc. For microscopes without an Abbe condenser or one having a substage five-opening hole disk diaphragm, you can still achieve darkfield illumination by cutting a rectangle out of a piece of clear plastic, placing a round black disk (from black paper) in the center and attaching it directly beneath the stage with tapepreferably gaffers tape, which does not leave a sticky residue. Experiment with the size of black disc to achieve the best result.

First, look into the eyepiece at a subject and position the plastic and disk until darkfield is achieved, then tape in place. This works, and I have taken excellent darkfield color slides this way.

Of course, it is easier to have an Abbe condenser. When I use a 'scope with a condenser, I usually just leave the plastic and centered disk in the filter holder and just swing it out when I need brightfield. I use a darkfield stop of about 12-15 mm approximately on the filter tray and it works quite well with the 4X and 10X objectives with 10X widefield ocular. I guess a bigger stop is used with higher magnifications, but with live material the 4X to 10X objectives work best. Also, it is interesting to try different filtersred, yellow, blue, green, etc. when using brightfield or darkfield illumination.
 
 

Eyepieces: I also recommend 10X widefield eyepieces with high eyepoint. I have one for each of my 'scopes.
 

Contributions by Comments to the author sent via our contacts page quoting page url plus : ('chuck','')">Chuck Huck, comments welcomed.
 

Compilation and images by Dave Walker.
 
 

For readers interested in further details/examples of darkfield or Polaroid filter useage in microscopy, type 'dark' or 'polar' into the keyword search engine of the Micscape Article Library; link below.

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Published in August 2000 Micscape Magazine.

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