Borescope Magnification

by | Dec 16, 2021 | Blog

What magnification does the borescope offer?  That sounds like a simple question doesn’t it?  But it is more complicated than it sounds.

Both microscopes and eye loupes usually have a very restrictive DOP (Depth of Field).  They can only focus images at a certain distances and therefore, their magnification is very limited.

A borescope, on the other hand, has an extensive DOF (Depth of Field).  There, borescopes are easier to use a users do not have to refocus them from time to time.

Here is the main point with magnification of a borescope: The closer you place a subject to your borescope’s lens, the more crisp and vivid will the magnification be.  In short, the greater the magnification.   In order to calculate magnification, you need to figure out the distance of your object from the borescope’s lens.  Whether you are using a rigid borescope, flexible fiberscope or video borescope, you need to follow the same method for both types of borescopes. The optical magnification of the borescope can be continuously changed with how close or how far away you are from you target inspection unlike a microscope objective, which gives a fixed magnification at one object distance.

Wider lenses see more, but at a lower magnification, giving less detail. Magnification increases as the borescope approaches the subject, unlike a microscope objective, which gives a fixed magnification at one object distance.  For example, let’s say you have a 4mm diameter borescope with a 40 degree DOF and you are about 20 mm away from your target inspection.  You can expect an approximate 5 X magnification.  If you get less than 5mm away and still have a clear image you can expect an approximate 12-15 times magnification.    If you have a borescope with a larger wide DOF you can expect less magnification.   If you are approximately 20 mm away from your target inspection you can expect an approximate 3 times magnification and if you get as close as 5mm or less you can expect up to a 10mm magnification.

When you are testing out your borescope take a known item such as a penny and test out the magnification changes as you move your borescope closer to the target area.  You can see for yourself how the borescope magnification varies greatly.   If you have a system that offers different field of views, both wide and narrow you can test this out as well.

The new endoscopes provide a magnification function by adjusting the position of the lenses located at the tip of the tubular probe.   Most of your videoscopes will provide a digital magnification on screen.   Some will supply 1,3 or even 8 times zoom.   In addition, once you save the image and transfer to your computer you can digitally zoom and enlarge the image.

Optical zoom endoscopes also enable doctors to observe magnified images for further inspection while maintaining high image qualities. This is distinguished from standard endoscopes with electronic or digital magnification, which simply enlarge the images on the displays with degraded image qualities/resolutions. Reports further highlighted that high-magnification optical zoom endoscopy may potentially allow specific characterization of some abnormal tissues that is sufficiently accurate to defer biopsy to save costs and improve efficiency.

We hope that this informative blog assist you with the understanding of how borescope magnification works.