The Siedentopf binocular microscope head explained
You’re probably familiar with the standard binocular microscope head – two eyepieces attached to a central body.
But you might not know that there are several different kinds of binocular heads, and that the wrong choice might cause you a little bit of trouble.
If you’re going to be sharing your microscope, the Siedentopf head is widely regarded as the best choice.
What is a Siedentopf head?
Named after microscopy pioneer and inventor Henry Siedentopf, Siedentopf heads are an easy and problem-free way to adjust the distance between the two eyepieces of a microscope.
They work in a similar way to binoculars – both eyepieces are attached to a central section so that when you move the eyepieces up or down, they rotate around the centre, becoming closer or further apart.
The big advantage of the Siedentopf head is that your microscope doesn’t lose focus whenever the eyepieces are adjusted.
Some microscopes use sliding heads, where you adjust the eyepieces by sliding them apart along a horizontal axis. Of course, this works, but by moving the eyepieces a greater distance apart, you increase the length of the optical tube.
As the focus point of the microscope depends on this length, this means that every time you adjust the eyepieces you pull your microscope out of focus.
The Siedentopf head gets around this problem by rotating around a central axis and keeping the length of the optical path constant.
Should you get one?
If you’re the sole user of a microscope you won’t need to readjust the eyepieces, so there’s no real need for a Siedentopf.
On the other hand, if your microscope is going to be shared, a Siedentopf head could save you a lot of irritation.
The distance between your eyes (the interpupillary distance) is rarely the same as another person’s. So, if you have to share a microscope, you’ll be adjusting the eyepieces every time you switch places. Having to bring the specimen back in focus every time can be a real chore.
The problem is exacerbated in a shared learning or working environment (school, uni or lab) where you’ll be constantly swapping eyepieces and microscopes – a genuinely frustrating experience for everyone involved.
You should also consider your budget and whether you need a binocular head at all.
If you’re on a tight budget or have a limited selection, there’s no reason to snub a non-Siedentopf microscope. Ultimately, it’s a quality-of-life feature and it won’t affect the practical functions of your microscope in any way.
You may also not even require two eyepieces at all. If you’re shopping for a cheap microscope or a microscope specifically for younger children, check out monocular microscopes. They’re less expensive (because of the single eyepiece) and are often easier for kids to use because the distance between their eyes is often too narrow to use any binocular microscope comfortably.
You can’t go wrong with a Siedentopf head but that shouldn’t keep you away from the joys of a microscopy hobby.
Further reading please refer to our blog article Different types of microscope heads explained