A few drops of water from my mini pond put under the microscope set up with the video camera:
To give an idea of size - the strap shaped object at about 43 seconds was approximately 2 mm long. That was the only thing I could see with the naked eye or even under a magnifying glass.
All the lenses are now working. The immersible ones are so close to the subject that they appear not to be working unless there is strong light from underneath. As there are no other lenses between the microscope and the video camera the magnification is not as great as it would be with a 'normal' set up. In some ways that is just as well as the little creatures soon disappear out of shot. The higher the magnification, the shallower the depth of field. As the creatures swim up and down they go in and out of focus.
What I really want is a cross table for the microscope. That allows fine movement to position the specimen which is needed at high magnification. Moving things by hand is very much hit and miss as a mm or two of movement can make the difference between seeing and not seeing a particular part.
5 hours ago