Closest distance of endoscope and borescope

The closest distance to the object within the in-focus range (observation distance) is called the closest distance.


The closest distance has characteristics depending on the type of endoscope.


1. Endoscope equipped with advanced camera

Since there is a camera at the tip, the optical closest distance is longer.


In the case of our endoscope, the closest distance is 10 mm.
The recommended viewing distance is 10-60mm.





Although it is made by another company, some low-priced models seem to have a closest distance of about 40mm.






2. Borescope


Borescopes and fiberscopes have relatively short closest distances.

This is not a guaranteed value as there are individual variations, but when connecting a camera with our borescope, the closest distance is approximately 5 mm.



Lens focus tonality can be adjusted, but there are limits.

The limit is around 5mm.

ボアスコープの最至近距離02   When we checked with our current product, the closest distance was 4.5mm.





◆How to shorten the closest distance


By inserting a close-up ring (5mm), the closest distance can be reduced to about 3mm.






When using our current product with a close-up ring (5mm), the closest distance was 2.5mm.





The “borescope camera” used this time is available at our company.

Additionally, our Borescope Camera Adapter Lens is equipped with a 5mm close-up ring as standard.

For details, please see the product page below.