Dedicated to optical precision components
and Solution of high-tech core solutions

Home page

Do you really know what an aperture is? If you don’t, take another look.

Release Date:

2020-08-17 11:30

Source:

Do you really know what an aperture is? If you don’t, take another look.

　　A light‑blocking ring serves to prevent stray light; for example, it’s used in smartphone camera lenses and other imaging optics. It’s made by stamping SOMA light‑blocking material into shape and is embedded within the lens as a Mylar sheet. Because of its light‑blocking function, it’s commonly referred to as a light‑blocking ring or a light‑blocking shim.

　　The purpose of a lens hood:

　　A lens hood is a common photographic accessory mounted in front of a camera lens, available in various materials such as metal, hard plastic, and soft rubber. As its name suggests, the primary function of a lens hood is to block stray light. A camera lens consists of multiple lens elements; when sunlight enters the lens, light rays can bounce repeatedly between these elements, leading to flare or causing images to appear washed out. Therefore, a lens hood helps improve image quality.

　　The blue line represents the light path under normal imaging conditions. The gray line, on the other hand, corresponds to stray light that is reflected from the bottom of the lens’s rear edge (shown in red). This light then propagates forward and undergoes another reflection at the lens’s front edge, ultimately returning to the sensor and giving rise to a halo effect.

　　When light enters the lens barrel, it forms a conical shape. However, the lens hood blocks unwanted light from the sides, transforming the image into a rectangular form. As a result, the photos we see are rectangular rather than circular. From this, we can infer that the light contributing to the image should ideally be a four‑sided pyramidal cone rather than a pure cone. Therefore, a lens hood effectively suppresses stray light, and images captured with a hood typically exhibit richer colors and deeper saturation.

　　Benefits of using a lens hood:

　　In addition to blocking excess light, lens hoods offer other benefits:

　　1. Using a lens hood can protect your lens, reducing the likelihood of accidental contact with and damage to the lens surface.

　　2. The lens hood can protect the lens from rain and dust.

　　3. When the lens is accidentally dropped, the lens hood helps minimize damage caused by the impact.

　　When should you not use a lens hood?

　　1. When using a wide-angle lens together with the built-in flash, the lens hood may block the flash light, creating dark shadows.

　　2. When using rotatable filters (such as a CPL), the lens hood may interfere with filter operation.

Unafraid of Backlight: Who’s Quietly Powering It From Behind?

kimoto: What are some common categories of Mylar film products that we may not be aware of?

Related News

VIC Ultra-Low-Reflectance Black Coating

Inside a lens assembly, reflections from metal spacer rings, lens retainers, baffle rings and the inner walls of the lens barrel can generate flare. The resulting artifacts include flare, halos, ripple-like patterns and ghost images, all of which degrade image quality, as illustrated.

Invitation to the 2026 Japan Optoelectronics Exhibition from Yamagata Optics

〇 A mature, stable production system and a precise stray-light elimination solution 〇 Addressing customer pain points—delivering products that deliver real value

The Yokohama Optoelectronics Exhibition in Japan concluded successfully, yielding abundant results.

Yamagata Optics manufactures shutter blades, apertures, bases, lens barrels, caps, spacers, and camera housings, which can perfectly address image quality issues caused by various types of stray light.

Ultra-Low-Reflectance Coatings for Metal Components Over 99.9% Light Absorption

Inside a lens assembly, reflections from metal spacer rings, lens holder, barrel,spacer , baffle rings and the inner walls of the lens barrel can generate stray light. The resulting artifacts include light streaks, halos, ripple-like patterns and ghost images, all of which degrade image quality, as illustrated.

Serrated-Aperture Diaphragms for Stray-Light Suppression

Yamagata Optical's patented serrated aperture-edge design offers clear advantages over conventional wavy-edge designs. This innovative geometry provides highly effective stray-light suppression. It reflects our long-standing commitment to advancing precision optical components through research and engineering innovation.

Ion Coating Dramatically Reduces Baffle-Ring Reflectance

Yamagata Optical's ion-coating process reduces baffle-ring reflectance by a factor of 8.6. In addition to multiple solutions for suppressing stray light at the aperture edge, we can apply an ultra-low-reflectance ion coating to both sides of the film used to manufacture baffle rings. After treatment, reflectance can fall below 0.3%, substantially improving camera-module optical performance.

Yamagata Optics lens hood ion plating technology

After ion-plating treatment, Yamagata Optics has achieved an 8.6-fold reduction in the reflectance of its aperture. Currently, in addition to multiple anti-glare and stray-light suppression solutions for the inner bore of the aperture, Yamagata Optics can also apply ultra-low-reflection ion-plating to both sides of the raw-material light-shielding film. Following this anti-reflection treatment, the reflectance can be reduced to below 0.3%, significantly enhancing the optical performance of the camera.

The Ultra-Black Revolution in Optics From 5% to 0.1% Reflectance: How Yamagata Optical Is Advancing Photonics

In optical imaging, light can be both essential and disruptive. An unwanted ray may reflect off a lens-barrel wall, scatter from a spacer ring or diffract at a baffle edge. The result can be ghosting, halos, light streaks, ripple-like artifacts or veiling glare that washes out the image. Together, these forms of stray light undermine image clarity, contrast and signal-to-noise ratio.