Video Transcript:
Today we're going to talk about how to use a magnifier. I have here a couple of magnifiers from SCHWEIZER, and the thing that magnifiers do is they have a focal length. You might remember, as a kid, you may have used a magnifier of some sort to burn an ant or a piece of paper or something like that. What happens is, if you picture light coming through these, the light then focuses at a single point. If you do that, you could use this very magnifier in the sun to set something on fire.
But we don't want to use it for that. We want to use it to make things look bigger. So you don't want to focus where that light focuses to a point. You want to go a little bit lower than that so that you have a full field of view, and so that everything looks bigger.
In general, the focal length of a magnifier is one over the diopter. So for an 8 diopter, it would be one-eighth of a meter, which would be about 12 centimeters. Compare that to this one, which is a 39 diopter. The focal length is 1/39 of a meter. So it's a very, very short focal length. Now with the shorter focal length, you'll also have a shorter field of view.
When you get into these stronger magnifiers, there's an interesting phenomenon that can occur that you want to make sure you are aware of. Remember how I was saying that the rays come in and then they come into a focus? What happens when you pull this past its focal distance? The rays actually flip, and everything looks upside down. So with a magnifier, you want to hold it short of its focal distance so that you get the maximum amount of magnification and the maximum field of view. And that's how you use a magnifier.
The other thing that's interesting is various companies make magnifiers, and the way the lenses are made is via injection molding. That's the majority of magnifiers. Some of them are glass, which is not injection molded. But if it is an acrylic magnifier, which is going to be much lighter weight, those lenses are injection molded. The interesting thing about injection molding is how the tooling works and how lenses are made in batches. And the calibration of the tooling is critical to the lens quality.
The cool thing about SCHWEIZER, and the reason that we love SCHWEIZER here, is that they actually re-polish and rework their molds on regular intervals. They have an internal shop that will recalibrate their molds very frequently. If you compare that to other factories that may not have very consistent calibrations, there's a good chance that your magnifier might not be what it's labeled as. So it is important to go with a magnifier that's made with quality and precision and calibration, because otherwise you don't know if an 8 diopter is actually an 8 diopter. And you may also see aberrations in the lens that have developed in the mold over time.
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Disclaimer: The information provided in this video is for educational purposes only and is based on our experience in optical solutions. We are not medical doctors. Consult with your ophthalmologist, neurologist, or other qualified healthcare professional before making any changes to your treatment plan. The solutions discussed are intended to support, not replace, professional medical advice.