A Simplified Technique to Parfocal the Dental Microscope

...Let's talk about a term you may have heard before, which is parfocal. 

 

Essentially, what that term means is that when you look through the microscope, if it's parfocal with your eyes, then when you move throughout the zoom range, an in-focus image will remain in focus. 

 

So if something's in focus at low magnification, it will still be in focus at high magnification, and that's the whole idea. 

 

Right now, my microscope is parfocal, but for the purpose of this exercise, I'm just gonna mess with my diopter rings here and just mess these up a little bit. 

 

There we go, and now I will no longer be parfocal. 

 

So how do we get your microscope parfocal? 

 

Well, typically, your representative will do this for you, but if there's different dentists using the same microscope, it's important to know how to do this. 

 

Or if your prescription changes over time, you, you'll no longer be parfocal with the microscope. 

 

So let's go ahead and figure this out. 

 

The couple things you'll need is you want your microscope, you want a piece of paper with some black text on it, so a white piece of paper with black text. 

 

It's just a really high-contrast image, and ideally, you wanna go ahead and tighten the tension knob on your microscope up here so that the microscope doesn't move up or down. 

 

You wanna keep this thing quite stable throughout the whole parfocal process, and then you can loosen that afterwards. 

 

So the first thing we'll do is we'll go ahead and zoom in to maximum magnification, and then we wanna make sure that, within our field of view, we can see some text. 

 

So this is in focus, and what you wanna do is bring the image in focus using the objective lens focus knob. 

 

You don't wanna touch these eyepieces yet. 

 

Once you've brought it into perfect focus, then what you do is you zoom all the way out to minimum magnification. 

 

Now, assuming your microscope is not parfocal, you'll have a blurry image when you look through the oculars. 

 

So what we wanna do next is we wanna leave the objective lens focus knob alone and bring the image into focus using the diopter rings on your eyepieces, and you do this one eye at a time. 

 

So I'm gonna look through the microscope, and I'm gonna go ahead and close my right eye because I'm gonna do my left eye first, and I'm gonna start spinning the knob until I see it come back into focus. 

 

And then I like to overshoot a little bit and then bring it back, kind of like tuning an instrument or tuning a guitar. 

 

You wanna just find that perfectly in-focus spot. 

 

And then I'm gonna switch to my right eye, and I'm gonna do the same thing, and turn the ring until I bring this into perfect focus. 

 

Yeah, it's looking really good. 

 

So now, what you wanna do is look at your numbers, and I can see that on my left eye, I'm about negative 1.5, and then in my right eye, I'm negative 2.0 , and you wanna record those numbers for your eyes. 

 

And the way to check to make sure that the microscope is actually parfocal after doing this is you then go ahead and zoom in through the entire magnification range and make sure that the image appears in focus through the entire zoom range. 

 

So at maximum, middle, and low magnification, everything should be in focus. 

 

If you've got that under your belt, then you know that the microscope is parfocal, and you're ready to go.