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Saturday, 19 November 2011

A bit more about microscopes and hand lenses

Sherlock Holmes and hand lens,
as seen in the Strand Magazine.

I have now ferreted out all of the discarded text on microscopy that might have gone in Australian Backyard Naturalist and didn't. The rationale was simple: we had about three times as much text as would fit in a standard book, and something had to go.

Realistically, not everybody has a microscope, and many of the readers might not have access to a microscope. Then there was the consideration that microscopy is not a core element of the publishers' mission statement.

That said, it is part of mine, and in any case, you can see quite a lot with a hand lens, as Sherlock Holmes knew.

Mind you, the Holmesian lens wasn't up to all that much, delivering a magnification of around x10, but there is a whole variety of hand lenses that we can call into service, and the one on the lower right can deliver about x20, as can a (fairly expensive) achromatic hand lens.

Let's remember, though, the $50 USB microscope that I mentioned in my last entry. That sort of thing ought to be in most people's reach, and the sorts of things I will be writing about here are all reachable with one of those: and some of them can be done, less satisfactorily, with a hand lens.

To be honest, some of the shots I am using here have come from one of the microscopes you can see on the right, and when it comes to thin sections, you can see the difference.  The gadget lying between them is the semi-professional USB camera that I use with those: its slips into the top of the microscope, in place of the objective.

I stopped half-way through the last paragraph to have dinner, and part of the meal was raw onion ( which we happen to like). Anyhow, I filched a small portion of onion and peeled the epidermis off it so I could make a slide and run it through the$50 toy.

From left to right, we have two versions on the $50 microscope, then a x100 and a x400 from the monocular microscope using the good light on the expensive camera.  The main difference, I think, is in the light source.  Still, anything you buy today will be better than the lighting Robert Hooke had to put up with in the 1660s.

We've come quite a long way since then, and perhaps the most important is that young Robert had to do his own drawings (or some of them: tradition has it that Sir Christopher Wren did some of the work).  We just use the computer, easy-peasy!

In the next entry, I will look at a neat method of cutting this sections using a nut, a bolt and a razor blade, and how to mount a slide with a cover slip.


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