Each magnifier offers a different approach to a problem – how well the solution will work in a given situation will depend on the properties of the magnifier. There are three factors that usually determine what a magnifier is best for:
- Optical power
- Focal length
- Size of the lens
They vary widely, and choosing the right magnifier for a specific eye condition or to perform a certain task will depend on choosing the magnifier with the right characteristics. With that said, we will take a deeper look at each of these factors and why they are important.
Depending on the optical power of the lens, we are able to see the details that we need up close. Optical 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 the lens while the object fits properly in the visual 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 make an object appear bigger. Higher diopters are achieved by a steeper curvature of 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
How big the magnifier's field of view is usually depends on this. It also determines the size of a magnifier and how compact it is. Generally, the lower the optic power you need, the more flexible you can be when choosing a magnifier.
For example, 2x magnifiers have big lenses and give you a wide field of view. They do not require a lot of optical power, since you would not be using them for tasks that need precision, but for those in which it's more important to be able to see a larger area.
When a higher optical power is required, that also affects the size of the lens and in turn of the magnifier itself. The more powerful lenses are, the bigger the curvature they need. That makes them more precise, but because they are smaller their field of view is reduced, so it might be difficult to use them when reading a book, for example.
Focal length is the distance from the lens where the object you want to view is in focus. This is important to consider, because it can mean the difference between doing your tasks comfortably or struggling.
Magnifiers with smaller magnifications offer a bigger focal length compared to those with bigger magnifications. With a bigger focal length you can view the object from farther away and still be in focus. However, a higher magnification means that both the object that you want to view and your eye will need to be closer to the lens to keep it in focus, since the focal length will be smaller.
These 3 factors play a major role when it comes to the comfort and aid that an optical magnifier can offer in your daily life, so it's good to take them into account when choosing one. If you feel like optical magnifiers are not strong enough for you, you can always try an electronic magnifier, a powerful device that offers a wide field of view in a computer screen and can reach magnification levels far higher than those of a traditional magnifier.
We hope that now that you have more information, you'll feel more confident when choosing a magnifier. Have a look at our collection of magnifiers and low vision aids and if you have any questions or require some support send us a message at firstname.lastname@example.org or give us a call: (+44)7 862 478 062