Each magnifier offers a different approach to a problem – how well the solution will work in a given situation, falls on the properties of the magnifier. Normally three factors will define the magnifier that would serve best.
The three factors that will determine the best magnifier to fit a situation are optic power, focal length and the size of the lens. Each of them plays an important role to aid vision and with the perfect values, ranging widely, depending on the task or condition you need them for. With that said we will take a deeper look at each of them and how they are important.
Depending on the optic power of the lens, we are able to see the details that we need up close. Optic power can be measured in two ways - the magnification of the lens and the diopter.
How big the magnification is, depends on how many times bigger we see an object through them, while the object fits properly in the vision field. If an object appears two times bigger, then the magnification is 2X; if it appears 5 times bigger, it's 5X.
Diopters on the other hand are the ability of the lens to bend light, in order to enlarge an object for us to see. Higher diopter is achieved by bending the lens, which enables for a bigger enlargement of the object you are trying to view. If you know the diopter of a lens it is also possible to tell how much their magnification is. A single diopter is equal to about 0.25 magnification.
Size of the lens
This is one of the most important factors that come into play, when it comes to the field of view, that your magnifier will be able to offer to you. It also determines the size of a magnifier and how compact it is. Based on your needs, you will be presented with various options and usually the lower optic power you need, the more flexible the size would be.
For example 2X magnification loupes have big lens and allow for a big field of view. They do not require a lot of optic power, since you would not be using them for precision related tasks. It is far more beneficial for you to be able to see larger area. When higher optic power is required, that also affects the size of the lens and in turn the magnifier itself. The more powerful lenses are, the more curvature they need. That makes them more precise, but it reduces their field of view, which makes them a bad choice if you decide to read a book for example.
Focal length is the distance from the lens, where the object you want to view is in focus. Magnifiers with smaller magnification, offer bigger focal length compared to those with a bigger magnification. Bigger focal length means that you can view the object from farther away and still be in focus.
Higher magnification would mean that both the object that you want to view and your eye, need to be closer to the lens to keep it in focus. This is important to consider, because it can mean the difference, between doing your tasks as comfortably as possible and doing a struggle. Same applies when it comes to vision impairing conditions.
Those 3 factors play a major role when it comes to the comfort and aid that a vision enhancer can offer in your daily life.