Binocular, ergonomic binocular, and trinocular microscope heads are different types of microscope heads that are designed for different applications and user preferences.

1. Binocular head: A binocular head is a microscope head that has two eyepieces, one for each eye. This type of head is typically used for general microscopy applications and is suitable for users who prefer to view the specimen with both eyes.  This is usually the most affordable option.

2. Ergonomic binocular head: An ergonomic binocular head is similar to a standard binocular head but is designed to be more comfortable and user-friendly. It may have features such as adjustable eyepieces, a tilting eyepiece tube, or a built-in diopter adjustment to help reduce eyestrain and improve the viewing experience.  A beam splitter can be added into or underneath most ergonomic heads.  So it's very simple to keep the best ergonomics while adding a camera port. 

3. Trinocular head: A trinocular head is a microscope head that has three eyepieces, two for viewing and one for photography or video. This type of head is typically used for applications that require documentation or documentation and is suitable for users who need to capture images or video of the specimen.

In summary, binocular, ergonomic binocular, and trinocular microscope heads are different types of microscope heads that are designed for different applications and user preferences. Binocular heads are suitable for general microscopy applications, ergonomic binocular heads are designed for user comfort, and trinocular heads are suitable for applications that require documentation.