Choosing a bench magnifier
There are some widely held misconceptions with regards to the level of image enlargement available from most standard bench magnifiers. There are many types of magnifier and it can be difficult to choose which is most suited to your requirements, to follow are some basic guidelines.
Generally speaking, a large lens magnifier is not powerful, in terms of its image enlargement strength, the power of a lens governs it's size, the greater the level of magnification, generally, the smaller the lens becomes! Most simple magnifiers, use a single lens, which will mean it has a relativly low threashold on magnification (usually around 4-6 dioptre). It is impossible to make a high powered single lens magnifier.
If you see magnifiers advertised with high power, it will ussually mean they have a flip over monocular (can only be veiwed with one eye) secondary lens, allowing compound magnification. We are often asked for high power, wide field magnifiers - they don't exist! Magnifiers are designed to be used either as low vision aids, or for low level image enlargement, for component inspection and manipulation.
If you require higher magnification, you will need a video or optical microscope. It is however always a trade off between, the amount of the subject retained within the viewing area (FOV Field of view). The depth of focus(DOF depth of focus), which is the distance an object can be moved towards and away from the magnifier, whilst retaining focus. Both of these reduce as the image is enlarged or magnified. You cannot harm your eyes by using a magnifier, however generally the more you spend, as with most things the better the quality of the optics and illumination and the less image distortion occurs. This makes them more comfortable to use over longer periods of time.
There are many different types of Magnifier and low vision aids, however generally for the professional user, only a couple will apply. We would recommend that when used in a professional environment, for prolonged periods, you budget for at least £100-£500. Stick with the higher quality units, using wieghted, or clamp bench stands for stability. Don't forget to also look at the way the subject is illumination, it should provide good colour temperature and a pool of shadowless cool light. If in doubt - ring us for a chat!