The microscope head carries the eyepieces of the microscope. There are monocular, binocular and trinocular heads. Here we’ll have a closer look at them.
Here you can only use one eye for viewing. Many educational microscopes have monocular heads, as they are the cheapest of all types. These days most introductory and children microscopes come with this type. Due to the smaller size and lighter weight, the microscope also becomes more portable. Many children also have a difficulty looking through the microscope with both eyes anyway.
Advantages: Lower cost, smaller size, less weight
Disadvantages: uncomfortable when looking longer through the microscope. Takes practice closing one eye or observing with both eyes open.
These are standard for stereo microscopes. Compound microscopes can also have them, but the image produced is not stereoscopic. Binocular microscopes are much more comfortable for long-term viewing. The inter-pupillary distance can be adjusted by moving the eyepieces either apart or together. Binocular microscopes also have a possibility to do a diopter adjustment, in case the two eyes are not equally good.
Advantages: More comfortable when viewing longer.
Disadvantages: Children might have issues, becasue you have to adjust the distance between the eyepieces and also the diopter adjustment. Less portability (especially in schools, where they have to be carried around). Unlike stereo microscopes, compound microscopes do not produce a stereoscopic image.
These have a third tube for the attachment of a camera (phototube). You also need a camera adapter in order to do photography. Often there is a lever that allows you to redirect the light between the eyepieces and the phototube. I generally recommend to buy microscopes with a phototube because it makes taking pictures for documentation and sharing online so much more convenient.
Advantages: Allows for the connection of a larger and heavier camera (DSLR). You can leave the camera attached, and record videos/take pictures even while looking through the microscope. You can also connect a mobile phone camera there.
Disadvantages: The usual things like size and cost, even though the price difference is not so much higher.