There is such a thing as dark field and bright field microscopy. The difference lies in the kind of light the user wants to employ to bring out the sharp details of the specimen. This is because some specimen details are  better viewed in a dark background while others look much clearer in a bright background. Let us find out more about this.

To be able to utilize dark-field and light-field, a light microscope is used. A light microscope is one that uses visible light to distinguish very small objects. However, these are quite expensive instruments and not so many schools can afford to have these in their laboratories.  These light microscopes will fall under two types, the bright or the dark field microscope.

What matters in microscopy are the following in descending order. Reaching the right contrast, which can be adjusted using the iris diaphragm, is the first thing a good microscopist must do. Once contrast has been achieved, it is time to find the focal plane so that you know in what layer you should be working on in your specimen and to have a perfect point of view of the object.

A good resolution is one of the most important steps. This will allow the observer to view very clear, very sharp details of the specimen. Lastly, the observer must have the ability to recognize what he is looking for as soon as he sees it. Remember, that tiny slide will give you a wide spectrum of objects. So before embarking, you must know what it is exactly that you are looking for.

So when do you use bright field microscopes and when do you use dark field microscopes? Let us go through this slowly. Bacteria, one of the smallest living creatures will appear invisible in bright field microscopy. The proper contrast will bring out its cell shape even in just 100 times magnification.

The bright field microscope is more commonly found in school laboratories. Dark field and phase contrast microscopes seem to be rarer in classrooms because of the high cost.

The bright field microscope functions as the light coming from a source under the stage called the condenser focuses the light upward through the specimen. The different parts of the specimen is seen as the light passes through bringing out the natural stains and pigmentations of the specimen. So even if the object is colorless, the image still comes out because of the thickness of some parts that refract the light and forming some shadows, giving it shape.

Sometimes, it is necessary to adjust to maximum contrast to make the image appear. But when this is done, there are some parts that may not come out at all just like the cilia in Paramecium.

What is special about a bright field condenser is the presence of an aperture diaphragm that controls the diameter of the ray of light that passes through. Opening the diaphragm makes the view brighter with little contrast. On the other hand, closing it would darken the field and increasing the contrast. But mind you, the use of the diaphragm should be kept at a minimum because it just might distort the image.

On the other hand, a dark field microscope makes use of an opaque disc found under the condenser lens so that only light that has been scattered by the objects found on the slide may be visible. Instead of passing through or being refracted, there is a reflection of light so that all parts are visible, no matter what color which appear bright white that is place in a very dark background.

Dark field microscopy is just like looking at a film negative where colors are falsely seen. But the details in this kind of viewing are very sharp. Therefore, if you are looking for better resolution, you might as well use a dark field microscope. If it is the right color you are looking for, then use the bright field microscope. Dark field is best when you are looking at something liquid with debris you want to focus on.

Actually, a dark field does not necessarily mean you need to buy a dark field microscope. A light microscope with higher light intensity will do just fine. It is just a matter of adjusting the contrast and focusing on low magnification.

The choice between using a dark field microscope and a bright field microscope depends on what view you want to see. Both have their uses and both have their disadvantages. Having both in your laboratory will indeed be very useful.