Lens Yongnuo YN 4/3 25 mm f/1.7 — prime lens for Micro Four Thirds

Yongnuo YN 4/3 25 mm f/1.7 is a compact prime lens designed for Micro Four Thirds (MFT) mirrorless cameras. With a 25 mm focal length (equivalent to approximately 50 mm on full-frame) and a bright f/1.7 maximum aperture, the lens is intended for general photography, portraits and everyday shooting. Its straightforward optical design delivers usable sharpness and subject isolation in a small, lightweight package suitable for travel and daily carry.

Advantages

The fast f/1.7 aperture provides improved low-light performance and allows for shallow depth of field to emphasize subjects against soft backgrounds. The lens’s compact size and light weight make it convenient for mirrorless camera systems, reducing overall kit bulk. Simple controls and an uncomplicated optical formula make the lens easy to operate for users who want reliable, predictable results for common shooting situations.

Suitable for

• Everyday street and travel photography
• Environmental and close-up portraits
• Indoor and available-light shooting
• Content creation and social media photos

Key specifications

• Format compatibility: Micro Four Thirds (MFT)
• Focal length: 25 mm (standard/normal field of view on MFT)
• Maximum aperture: f/1.7
• Aperture diaphragm: multi-blade design (rounded blades for smoother bokeh)
• Optical type: prime (fixed focal length)
• Focus type: manual or autofocus depending on camera support and lens version
• Physical characteristics: compact and lightweight construction suitable for mirrorless bodies

How to use

Mount the lens on a Micro Four Thirds camera body using the native MFT mount. Select aperture priority or manual exposure to take advantage of the wide f/1.7 aperture for low-light shooting and shallow depth of field. For portraits, position the subject several meters from the background to increase background blur; stop down to f/4–f/8 when greater depth of field or sharper overall scenes are required. Use camera autofocus if supported by your camera and this lens version, or focus manually where precise control is preferred.

Usage recommendations

To maximize sharpness, avoid the smallest apertures when diffraction may reduce resolution; use f/2.8–f/8 for general-purpose work. When shooting in low light, increase ISO gradually and stabilize the camera with a tripod or image-stabilized body where available. Clean the front element with a microfiber cloth and a blower to maintain image quality.