Lenses, lens’, loupes and magnifiers – no matter what you want to call them, there is no doubt that getting close-up and personal with your newly-found treasures opens up a whole new world to discovery and learning. The hand lense is a standard tool for almost everyone and every discipline from geology to archaeology and palaeontology, not to mention anyone else into minerals and precious gems who needs that extra, portable magnification for your work. There are a whole bunch of different lenses out there on the market, different styles, different makes, different models, different magnifications… so which one is best?
For the standard explorer of the Earth and Archaeological sciences, we definitely recommend using a hand lens, rather than the more traditional magnifying glass. Yes, the range of view is a lot smaller on the hand lense, but the design allows greater magnification of your specimen. The smaller, compact design of a hand lens is heaps easier to carry around and look after than regular magnifying glass, especially in the field.
So, which magnification? You can get anything from around 2.5x, through 40x… but like the old saying goes, “bigger is not always better”. For the average user, the best magnification to go for is the 10x. Realistically, unless you are a jeweler or you need to inspect the carats of diamonds, 10x should suit you perfectly. We've used a 10x our whole working life and can’t really imagine a time when anything higher would even be useful for our work (the 10x magnification is perfect for getting close-up on things like sediments for grain size, and looking at tiny fossils). Also remember, the higher the magnification you have, the shallower the depth of field.
There are a few different types of hand lenses out there – single lenses, doublets (twin glasses) and triplets (tri-bonded glasses). Like everything, the quality of your hand lense is mostly governed by cost. You’ll find that the best quality lenses tend to be the most expensive. The leaders by far are the triplet designs (check out Dig It Up’s best models: Belomo 10x 21 mm, the brilliant Hastings 10x 18 mm and Hastings 10x 21mm hand lens designs). They generally give the best view of the specimen under magnification and are less vulnerable to perspective and colour distortion. Go for glass lenses, rather than plastic- the glass ones are much more resilient to scratches and will generally last longer.
Using the standard hand lense is pretty straight forward. Unlike a regular magnifying glass, you need to hold the hand lense right up to your eye, say within about 1 cm. Maneuver the specimen that you are trying to look at right in front of the hand lense to get it in focus. Easy! It pays to make sure that you are working in a well-lit area – you’ll be able to see your specimen better. That’s pretty straight-forward if you are in the field, but I also use my lense in the office if I don’t have a stereo microscope close by. In those situations, if you need extra light, we also stock a couple of brilliant models that have their own in-built LED lights.
Finally, a quick tip on hand lense maintenance – if you look after it, it’ll serve you well and will last a long time. Most hand lenses are foldable, so always keep the glass tucked away unless you need to use it. This way you’ll reduce the possibility of scratching the glass. From time to time, you’ll also need to ensure that the screws on the folding mechanisms are kept in check. Too loose and the lense will fall apart; too tight and it’ll be a pain to use. Keep the screws tight, but never over-tighten. When working in the field, it always pays to keep the hand lense on a lanyard that you can wear around your neck. Our Dr G has made the mistake of not doing this and actually lost the very first hand lense that he ever bought on the very first geology fieldtrip that he ever went on (rookie mistake!). Finally, for maintenance, try to keep grit and dirt away from the glass. You can keep the hand lense clean with a soft cloth, such as those that are used for cleaning regular reading glasses.