This is a photograph of a small trichome on the surface of a seedling through the 40x objective. Not sure if it is a happy trichome looking up at what it will become or a sad trichome looking down ๐ I liked the colors and the scene, reminds me of a painting.
Here is a photo through the 10x:
Haha, I think I have a good idea of why.... When thinking about general photography, common scenes involve many different types of objects of varying sizes and distances. In this context it makes sense to define the "field of view" of a lens in terms of the visual angle, and to think about differences between equipment in terms of a "reference" - that's where the 'crop factor' comes in, when comparing to a 35 mm film as a standard to measure relative to. It is a bit silly to ask a question such as "how many cats can fit into the image that gets projected into the camera sensor?"
When one gets into macro photography things start changing. The distances between the camera and the subjects are defined more narrowly and the size of the subjects one tries to capture is closer in size to the camera sensor's size. In macro-photography you hear about things like a "1:1" lens, meaning that the image of an object placed at a specific distance will be replicated 1:1 at the camera sensor's position. It becomes then meaningful to think about the camera sensor size in absolute sense, because a sensor will capture a scene of its own size (for 1:1). You can still think in relative terms using the crop factor, but it is not as useful to make relative comparisons anymore because the absolute scale is already giving us information that we can work with directly.
For microscopy this trend continues - the distance to the subject is well-defined and we can think in absolute terms about the magnification of the image that gets projected into camera sensor.
I have not looked into this! I am not sure.... I will look it up.
I do have a ruler but I misplaced it and I have not used it in a while. So, not really, I wouldn't say it is "calibrated". I did take some photos of the ruler that I can use to get a good rough estimate if I can find them.