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Dioptre explained
Magnifying lamps are commonly used by podiatrists, dental clinics, dermatologists, paediatricians, jewellers, watch and electronics repair, industrial inspection, scientific research labs – also for general examination use in a clinical setting. They are considered an essential tool when working with inspection, precision assembly, or design. Lighted magnifying lamps offer you the ability to view small details effortlessly, and as a result, they are extremely helpful in preventing eye strain and reducing vision fatigue.
This guide will increase your understanding of DARAY’s LED Magnifying lamps and should help you decide if it best suits your intended application.

Why buy a magnifier with a built-in LED light?
Despite the many advances in the field of lighting, most workplace locations still suffer from poor and indirect lighting conditions. This lack of efficiency of light distribution can directly result in marginal viewing performance, so good lighting is always a crucial element to consider. A Magnifying lamp compensates for this with a pattern of LED modules arranged around the magnifying window, to illuminate the object being viewed. Whilst Halogen and Fluorescent light sources are available too, these are not as energy-efficient as LED technology, which also tend to last far longer and require no further maintenance, along with no requirement for bulb changes – saving further cost over the lifetime of the product and eradicating downtime.

What does the term ‘Dioptre’ mean?
You will often see the term ‘dioptre’ used when searching for a magnifier. This, quite simply, refers to the amount of curvature in the lens. The higher the dioptre value, the more powerful the magnification, and the greater curvature of the lens. The term ‘dioptre’ directly identifies the refractive capacity of a lens, which is different from the term ‘magnification’. Magnification is the degree to which the viewed object is enlarged, this is usually expressed by the symbol ‘x’, which denotes the viewed size of the object in relationship to its actual size. To find the magnification level, a simple calculation is used: Locate the ‘dioptre’ number of the product you are looking to find the magnification value of (for example, the DARAY MAG700 is available in 3, 6, and 12 Dioptre options), divide that number by 4, then add 1. I will show this calculation using a 12-Dioptre lens: 12/4 + 1 = 4x. The 4x magnification value found equates to a 400% enlargement of the viewed object. To ascertain which ‘dioptre’ lens you should be purchasing, you are not just considering how ‘large’ you want the object to appear in the viewing window, you also have to take into account the focal length.

Dioptre
value
Magnification
(equivalent)
Objective
size increase
2 1.5x 150%
3 1.75x 175%
4 2x 200% 
5 2.25x 225%
6 2.5x 250%
7 2.75x 275%
8 3x 300%
9 3.25x 325%
10 3.50x 350%
11 3.75x 375%
12 4x 400%

What does 'focal length' mean?
The term ‘dioptre’ as described above has a direct correlation with the focal length. This is a measurement of the distance between the lens and the object, to the point where the object remains in focus to the user. Consider the fact that most uses for a magnifying light require space above the object and below the lens to work, typically with hands/tools. Consider what happens when shining a torch onto a wall – you reduce the distance (focal length) when you move the torch (magnifier) closer to the wall. In turn, moving away from the wall has the opposite effect, and the distance (focal length) increases. The higher the magnification of your chosen lens, the shorter the focal length, meaning you would need to have the object closer to the lens to achieve focus, thereby reducing the space in which you have available to work between the lens and the object. If little space is required, you will benefit from a higher magnification – these high-powered lenses are usually reserved for very close inspection and minute measurements. Requiring lots of space to work between the lens and object, such as for fiddly tools and complex procedures, means you will need to purchase a lower magnification, allowing greater focal length (space in which to work). To sum up the above, with a higher magnification/dioptre value, the focal length and field of view (FOV) within the lens become smaller.

What is ‘Field Of View’ (FOV)?
The field of view is the size of the magnified area that is in focus under the lens. The lens actually remains the same size, however due to the increased curvature of the lens in line with a higher magnification (dioptre), the field of view diminishes accordingly. To refer back to our torch analogy from above, consider that as you move the torch closer to the wall (higher dioptre value/stronger magnification/reduced focal length), the spot of light on the wall from the torch becomes smaller (field of view).

Other benefits
Our magnification lamps are mounted on a set of spring-balanced arms, which, in turn, would be coupled with one of a variety of mounting choices that we have available – such as a wall bracket, or a desk clamp, among others. A major benefit of having the magnifying lamp mounted to a surface is that it offers you the freedom of being able to use both hands within your work, whilst continuously viewing the object under magnification. In most applications, the benefit of hands-free operation is vital and boosts productivity.

Tips for best use
  • Similar to how you would use a pair of prescription glasses, ensure to use both eyes when viewing objects via a magnifier. If you are new to using a magnifier within your work, you may struggle to focus your vision for a few moments, do not worry – this is just because your eyes are adjusting to the increased amount of light they are receiving from the lens.
  • Always maintain good posture for best results, and if need be, adjust the position of your working surface or the height of your chair. Another benefit of having the magnifying light mounted on a set of manoeuvrable arms is that you can position the lens exactly where it is needed, and to assist you in avoiding bad habits such as leaning too far into, or away from, the lens.
  • Keep your eyes at a steady distance of approximately 8 to 10 inches from the lens. At this distance you will experience the least distortion of the image.