– When using a side-viewing (90°) borescope, attention must be given to the focal length.

Utilizing a side-viewing configuration inevitably results in a shorter distance to the wall surfaces (indicated by the red arrow).

 

 

 

 

– Upon magnifying the tip of the side-viewing borescope, it appears as follows.

 

 

• Compared to the direct-viewing type, the side-viewing type has a shorter actual focal distance (indicated by the blue arrow) due to the distance represented by the red arrow.

 

• In practice, a 4mm diameter side-viewing borescope was employed to observe the sidewalls of holes with diameters of 4.5mm, 6mm, and 7mm.

 

 

 

Even when utilizing the focal adjustment feature of the side lens with a diameter of φ4.5mm, the focal point remains entirely unaligned.

 

 

 

■The focal point barely aligns on the side with a φ6.0mm aperture.

However, discrepancies in product manufacturing may result in misalignment.

 

 

 

 

 

■On the side with a φ7mm aperture…

There is ample room for adjustment in the lens’s focal adjustment capability. Even accounting for variations in product quality, the distance remains sufficiently usable.

 

 

 

 

 

Observation of the side with aperture diameters smaller than φ6mm is made feasible through the utilization of a macro lens attachment ring.

 

 

 

 

 

I observed the side with a φ4.5mm aperture diameter by inserting a 5mm macro lens attachment ring.

 

■Observation of the side with a φ4.5mm aperture diameter (with the addition of a 5mm macro lens attachment ring)

Even at φ4.5mm (with a distance to the wall of 0.25mm), the focal point aligns.

(The presence of a distance between the lens and the mirror within the borescope allows for focal alignment even at 0.25mm.)

 

 

 

 

 

■Observation of the side with a φ6mm aperture diameter (with the addition of a 5mm macro lens attachment ring)

There is still room for further adjustment.

 

 

 

 

 

 

When observing the side with a φ4.5mm aperture diameter using direct (0°) wide-angle viewing, the macro lens attachment ring is unnecessary. (Adjustment is possible within standard specifications.)

 

■Observation of the side with a φ4.5mm aperture diameter (wide-angle, direct viewing)

 

 

 

 

The appearance when observed with the standard type of direct viewing is as follows for reference.

 

 

 

 

Please refer to the following for detailed product information on the “φ4mm side-view borescope” and the “5mm macro lens attachment ring” being used this time.