There are two adaptors included, and they are of different lengths. This is because some microscope eyepieces require the camera lens to be closer to the eyepiece than others do.
As humans, when we look through the eyepiece we naturally move our eye closer or further away from the eyepiece until we get a clear, circular image of the slide. With the Visualiser, the two adaptors can be swapped to find the ideal one for the adaptor that you’re using.
What you’re aiming for is a circular image on the display, with a sharp edge.
Best Way to Focus the Microscope
Start with the microscope out of focus, looking at a slide. Attach the adaptor, getting the Visualiser to look down the microscope so that you can see a clear circular image (i.e. no blurring around the edge).
Use the Focus Lock feature on HoverCam to lock the focus. This stops the Visualiser constantly autofocussing during use. Also, if you are using an eyepiece graticule, it will focus the Visualiser onto this.
Finally, use the Microscope focussing dials to bring the slide clearly into focus.