Posted on 19 February 2011 at 12:20h

The postman had to make his way down our slippery path to ring the doorbell this morning as the first consignment of our group 4 project equipment arrived. 14 magnifying glasses and 14 compasses all individually wrapped. The magnifying glasses seem great but some of the compasses seem to have become de-magnetised (easily fixed). I ordered these about a week ago from my favourite supplier  E Bay. Over the years I have bought Nichrome wire, Neodymium magnets, spectrum glasses, potty putty, jumping footballs, and lots more. It's a great way to fill your cupboards. The magnifying glasses are advertised as x40 magnification and they do seem pretty thick but there's quite a lot of distortion around the edges so they work fine close to the eye but not so good at a distance a good example of how reducing the aperture size (by the iris close to the lens) reduces aberration. You can see in the photo how the magnification is greater towards the edge of the lens as well as a bit of chromatic aberrations.