Greater portability for travel, concerts, and spectator sports
Lightweight and compact
Medium Diameter Binoculars
Effective diameter of 30 mm range
Standard type with a balance of portability and brightness
Large Diameter Binoculars
Effective diameter of 40 mm and higher
Focus on brightness for usage in dark scenes such as dawn and dusk
Greater light collection ability
Objective Lens Effective Diameter and IS Effect
At the same magnification, the larger the objective lens effective diameter, the easier it is to see in dark surroundings. You can choose a model that fits your intended use.
Relationship between Effective Diameter and Size
Just as cameras, at the same magnification, the larger the lens diameter, which serves as the entry point of light for the binoculars, the easier it is to see in dark surroundings. Large diameter binoculars with an objective lens effective diameter of 40mm or more are recommended for dim locations such as star observation and birdwatching in early morning hours.
A: At the same magnification, the larger the effective diameter, the brighter the image is.
B: Even at the same effective diameter, IS function is able to reduce shaking to obtain clearer image.
Images are easier to see even in dim light conditions when binoculars are equipped with an IS function
With the same effective diameter, binoculars with an Image Stabilizer function provide a more stable image viewing experience. It also makes binoculars easier and more enjoyable to use under dim light conditions. A larger diameter binoculars model with IS function would provide even clearer images!