Headband Magnifier FAQ’s
There are some optical (physics) rules that constrain magnification for headband magnifiers
- Is the inverse relationship between lens size and lens power. As lens power goes up lens size and field of view go down.
- Also as magnification goes up, focal length (working distance) goes down (gets shorter). Because of this once magnification goes beyond 3.5 the focal length gets so short that its impossible to have binocular vision (meaning seeing the sample spot with both eyes). Because of this maximum magnification for headband magnifiers is 3.5x. A complex lens structure like a medical dental loupe can extend the focal length , however they are much more expensive and have a very reduced field of view.
- As Magnification goes up field of view goes down. This means that the area being magnified ( in view) will get smaller as magnification goes up, and gets larger as magnification goes down.
- As Magnification goes up depth of field meaning the close/far distance to which the viewed item or area is in focus will become much more narrow, and as magnification goes up it will require a more steady head distance to keep the item in focus.