Topical Tips 7

contributed by Chuck Huck, USA and Ron Neumeyer, Canada

 

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 our readers, 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.

 

Use a PLAN Objective for Low-power Viewing

Most microscopes used by hobbyists are equipped with achromatic objectives, and these certainly provide excellent results for most applications. Microscopes equipped with PLAN flat-field objectives cost considerably more money, whether new or used, and are employed mostly by the scientific and medical profession. To change your microscope over to all-PLAN objectives would be very costly indeed, and in most cases would not be worth the effort.

On the other hand, I have found that one PLAN objective is very useful for viewing certain specimens, such as pond samples, and that is the low-power 4X objective. I recently replaced the normal 4X objective with a PLAN 4X but maintained the achromatic 10, 20 and 40X lenses on the microscope. The low-power PLAN is quite useful when viewing a wide field with high eyepoint widefield 10X oculars. Everything is in sharp focus from center to edge. I feel it is more important to have a flat field at low power than at high power because of the area covered and the greater depth of field. One does not have to continually focus to achieve edge sharpness and center sharpness. The higher powers—10X and above—cover a much smaller field, and the fine focus is usually employed to compensate for the much shallower depth of field. Since depth of field is much less critical at 4X, flat-field observing is much easier on the eyes.

The low-power PLAN objective is also less expensive than the higher powers, usually about half the cost of a 10X PLAN lens. The only drawback to the low-power PLAN objective is that it is not parfocal with the other objectives and focuses higher than the standard 4X. I don’t find this particularly annoying because I can switch to 10X and focus down, or move the stage up as the case may be,  rather quickly without crashing into the cover slip. Then all the other objectives are parfocal.

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

Temporary seals for aqueous mounts

Here is a neat tip I picked up from one of my older texts that your readers might find useful.

You can keep aquatic micro-organisms alive for ages with a Vaseline seal. The trick is in the application. It takes a bit of practice. You spread a very small amount of Vaseline on the heal of your hand. Now rub each edge of a coverslip across this area and place it on the sample (a good one to try are scrapings from your teeth an hour or so after a meal - lots of stage bacteria and small amoebas). I have been able to keep some slides going for days this way.

Contribution above by Comments to the author sent via our contacts page quoting page url plus : ('rneumeyer','')">Ron Neumeyer, comments welcomed.
 
 
 
 

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Published in November 2001 Micscape Magazine.

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