Sigma 28-70mm Zoom Lens Instructions and Technical Specs
1. Technical Specifications
The following table outlines the structural, optical, and physical specifications of the lens.
| Specification Feature | Details & Measurements |
|---|---|
| Focal Length | 28 – 70mm |
| Maximum Aperture | f/2.8 |
| Minimum Aperture | f/22 |
| Lens Mount | Sony E-mount |
| Format Compatibility | Full-Frame (Can be used in APS-C crop mode) |
| Minimum Focus Distance | 19 cm / 7.5 in. (at 28mm) 38 cm / 15 in. (at 70mm) |
| Maximum Magnification | 1:3.3 (at 28mm) 1:4.6 (at 70mm) |
| Optical Design | 16 Elements in 12 Groups |
| Diaphragm Blades | 9, Rounded |
| Focus Type | Autofocus (Stepping Motor) |
| Filter Size | 67 mm (Front) |
| Dimensions (ø x L) | 72.2 x 101.5 mm / 2.8 x 4.0 in. |
| Weight | 470 g / 16.6 oz. |
2. Lens Anatomy and Controls
The lens body features two tactile rings for manual adjustments:
- Zoom Ring (Front / Larger Ring): Rotate to adjust the focal length from 28mm (wide-angle) up to 70mm (portrait perspective).
- Focus Ring (Rear / Smaller Ring): Rotate to adjust focus manually when your camera body is switched to Manual Focus (MF) or Direct Manual Focus (DMF).
3. Instructions for Use
Mounting and Detaching the Lens
- Turn off the camera body before changing lenses to minimize environmental dust adhering to the image sensor.
- Align the white mount index dot on the silver base of the lens with the matching index dot on your Sony camera mount.
- Insert the lens firmly into the mount and rotate it clockwise until it clicks securely into its locked position.
- To remove, hold down the camera’s lens release button and rotate the lens counter-clockwise.
Attaching the Lens Hood (LH706-01)
- Normal Operation: Align the indicator line on the lens hood with the top index point of the lens barrel, push forward gently, and turn clockwise until it clicks into place. *Note: Always use the lens hood to eliminate stray ghosting flares and shield the front element from accidental glass impacts.*
- Storage Mode: The lens hood can be reverse-mounted onto the lens barrel to save space inside your equipment gear bag.
4. Best Practices for Filmmaking and Photography
Maintaining a Constant f/2.8 Aperture
Because this lens features a constant f/2.8 maximum aperture, your exposure value and lighting balance will remain uniform while zooming. This prevents sudden exposure drops or exposure hunting mid-take when filming video.
Working with Close-Up Focus Distances
The close-focus capabilities alter based on your active focal scale selection:
- At 28mm, you can position the front of the lens as close as 19 cm (7.5 inches) to your subject for unique wide-angle macro perspectives.
- When zoomed into 70mm, ensure you step back slightly, as the minimum focus limitation shifts back to 38 cm (15 inches).