Category: Science facts

What’s the most important detail to consider when buying a microscope?

 

Photo from http://blog.microscopeworld.com/2011/10/stereo-microscopes-greenough-vs-common.html

 

What would Science be without microscopes? I can’t imagine being able to teach my students about science without this indispensable optical instrument. In fact, I own two types of microscopes: a stereo microscope and a compound microscope ( to understand the different I recommend this article).

I wanted a well-built microscope that can withstand years of use. I specifically wanted quality components and construction that will ensure the device can last a lifetime. I looked for a model with a well-built and sturdy frame. I read somewhere how the best ones are constructed of metallic alloys that ensure minimal vibration.

This also provides reduced fluctuation due to variations in temperature. I never even looked at plastic microscopes because I wasn’t buying a toy–I was buying a useful optical instrument and nothing less. For those thinking of getting a microscope, be wary of models that have been chromed or painted to look like they are made of metal.

The optical lenses of my microscopes are made of glass. Attached to the metal frame are metal focus gears that are connected in turn with screws made of metal. I made sure the finish of both devices is resistant to reagents used for specimen treatment and mounting. Since the vital moving parts deserve more than just grease, I made sure they had ball bearings that ensure smooth operations.

My advice when buying online? Compare the instrument’s actual weight and measurements to get a clue on the sturdiness and size of the unit. Do not rely on shipping weight, as it can include packaging components.

Good quality microscopes are painted, sanded then painted again, and then to ensure durability, are subjected to a baking process.

The most crucial detail on any microscope is the optics, no matter how they just form part of the entire package. This means a quality focus system should accompany top-quality lenses, which are worth next to nothing unless packaged so. Therefore, it is best to assess a microscope as an entire unit and not just according to its individual components.

Microscope objective lenses are evaluated based on international standards, which include Deutsche Industrie Norm (DIN) and JIS, the latter being a Japanese standard. It is always good advice to get a microscope that conforms to the DIN standards for length and threading. This will enable you to replace any damaged or lost objective lens with any lens from any microscope brand.

A microscope without a DIN standard compliance is rendered useless should the lenses get stolen, lost or damaged.

Achromatic lenses are best thanks to their being color corrected. This means each objective lens is constructed using 10 or more glass lenses correctly configured together to ensure clarity and the ability to view an image. Achromatic lenses also ensure a flat image that gets focused while eliminating any aberration.

Fine lenses are made while adhering to stringent processes ( more on this ). Achromatic lenses place any spherical and achromatic aberrations in the field of view’s outer 40 percent. Typically, the field of view’s outer rim will look curved out of focus, which is normal since the subject is to be centered anyway, and which also means you won’t even need to look at the outer rim.

Bear in mind that 100-percent aberration-free lenses, otherwise known as Plan Achromat lenses, come with a hefty price tag and are usually part of research and medical microscopes that cost upwards of $1000. All that students, schools and hobbyists need are achromatic lenses.

Stay away from toy microscopes with plastic lenses that only provide fuzzy images.

Look for an instrument with an eyepiece that offers a wide field of view, which ensures a significantly larger lens opening compared to an instrument that doesn’t have a wide FOV. The wide field of view makes it easy to position your eye into the eyepiece. My microscopes have wide field eyepieces each measuring 18mm, as is typical.

The wide field of view also enables me to teach kids about microscopy effortlessly. They can easily look at what I had brought into focus.

A microscope is an instrument that is fun to use. Make sure you get a top quality instrument to make the most of the device for learning and as a hobby.