How to Choosing The Right Magnifier
When trying to find a good magnifier, it is important to match it to the work you will be doing. After determining the character and size of the subject along with its surface you will be ready to begin your search.
If low power is all you need, then a single lens is adequate. However, as the power need intensifies two or more lenses may be required to improve correction and resolution capabilities.
Another important element in the selection of a magnifier is the distance from which it will be used to view object. A longer working distance allows for more movement between the object and the lenses when tools are used when working with an object, so be sure to consider this when searching for the right device.
Field of View
Field of view offers something else to think about when selecting the appropriate magnifier. Larger surfaces are best viewed through lower power systems while the opposite is true for smaller ones. This is because as the power increases you get a decrease in the field of view. For instance, your view will include around 1.5 inches with 5x power while it is only 0.5 inches with 10x power.
The eye relief is the longest distance from the magnifier that the eye can be and still enjoy the entire field of view. The longer the eye relied the greater the comfort is during viewing.
Depth of Field
With every increase in power you will lose some depth of field. What that means is that you need to be closer to the object being viewed the more power your magnifier provides.
When using magnifiers in low light levels anti-reflective coatings help reduce the loss of light so that you can see the object better.
The eye can only maintain good focus on items that are at least 10 inches away. Magnification is used to help us see things that are closer to us. Eye relief distance, working distance and power all vary a bit with each observer.
Power and Size in a Magnifying Glass
There is no such thing as the perfect magnifying glass because it would need to be light weight, large in size, offer wide range of view and be free of distortion. It is not possible to create a single magnifying glass that incorporates all of these properties because all of them are dependent upon the curvature of the lens. This in turn affects its size, weight, range and distortion and no one lens is perfect for every job.