Viltrox AF 20mm F2.8 FE Lens
Product Overview
The Viltrox AF 20mm F2.8 FE is a wide-angle prime lens designed for Sony E-mount cameras. It features a large f/2.8 aperture for excellent low-light performance and shallow depth of field. The lens is lightweight at 157g, making it ideal for travel and everyday photography.
This document provides detailed information regarding the lens's features, specifications, optical performance charts, and usage guidance.
Key Features
- Focal Length: 20mm
- Maximum Aperture: f/2.8
- Lens Mount: Sony E-mount
- Full-Frame Compatibility
- Autofocus (AF) STM Stepper Motor
- Lightweight Design (approx. 157g)
- Suitable for various photography genres including landscape, street, and astrophotography.
Optical Performance
The lens exhibits strong optical performance across its aperture range. The following charts illustrate its performance characteristics:
Modulation Transfer Function (MTF) Charts
The MTF charts display the lens's ability to resolve detail at different spatial frequencies (line pairs per millimeter) and distances from the center of the image. Higher values indicate better sharpness and contrast.
Sagittal Field MTF: This chart shows the resolution for lines oriented radially from the center of the image.
Meridional Field MTF: This chart shows the resolution for lines oriented tangentially to the center of the image.
The charts typically show performance at the maximum aperture (f/2.8) and stopped-down apertures (e.g., f/5.6, f/8) across the image field (center, mid-field, edge).
Distortion Chart
This chart indicates the degree of barrel or pincushion distortion present in the lens. The Viltrox 20mm F2.8 FE is designed to minimize distortion, which is crucial for architectural and landscape photography where straight lines are important.
Specifications
| Parameter | Specification |
|---|---|
| Focal Length | 20mm |
| Maximum Aperture | f/2.8 |
| Minimum Aperture | f/16 |
| Lens Construction | 10 elements in 8 groups (including 3 ED elements and 2 aspherical elements) |
| Diaphragm Blades | 9 blades |
| Minimum Focusing Distance | 0.25m (approx. 9.84 inches) |
| Maximum Magnification | 0.17x |
| Filter Thread Size | 62mm |
| Weight | Approx. 157g (5.5 oz) |
| Dimensions (Diameter x Length) | Approx. 65mm x 83mm (2.56" x 3.27") |
| Mount Type | Sony E |
Lens Diagram and Components
The lens is constructed with a sophisticated optical formula to achieve high image quality. Key components include:
- ED (Extra-low Dispersion) Elements: Used to minimize chromatic aberration, resulting in sharper images with better color accuracy.
- Aspherical Elements: Help to correct for various aberrations and improve image sharpness and contrast, especially at wider apertures.
- Aperture Ring: Allows for manual control of the aperture.
- Focus Ring: Enables manual focusing.
- Electronic Contacts: Facilitate communication between the lens and the camera body for autofocus and aperture control.
- Lens Hood Mount: For attaching the included lens hood.
- Filter Mount: For attaching standard filters.
The internal structure consists of precisely arranged lens groups and elements, along with the autofocus motor and electronic components.
Usage and Handling
Attaching the Lens: Align the white dot on the lens with the white dot on the camera mount and rotate the lens clockwise until it clicks into place.
Detaching the Lens: Press and hold the lens release button on the camera body and rotate the lens counter-clockwise.
Autofocus: The lens utilizes an STM motor for quiet and smooth autofocus. Ensure your camera is set to autofocus mode (AF-S or AF-C) for automatic focusing. Manual focus can be achieved by rotating the focus ring.
Aperture Control: Aperture can be controlled via the camera body or the lens's aperture ring (if applicable to the camera model).
Lens Hood: Attach the lens hood to reduce lens flare and ghosting caused by extraneous light sources.
Maintenance
Keep the lens clean by using a soft brush to remove dust and a microfiber cloth for smudges. Avoid using harsh chemicals or abrasive materials. Store the lens in a dry, dust-free environment.
