Sony E Autofocus

SG-image AF 25mm F1.8

Focal length: 25 mm
Aperture: f/1.8
Weight: 145 g
Filter diameter: 52 mm
Min. focus distance: 30 cm
Length: 32 mm

Overview

The SG-image AF 25mm F1.8 is a compact autofocus standard prime for APS-C mirrorless cameras. SG-image offers it for Sony E, Fujifilm X and Nikon Z, in black and silver. The 25mm focal length gives a field of view comparable to about 37.5mm on full frame, a normal view that is slightly wider than the classic 50mm equivalent. SG-image calls it possibly the slimmest autofocus 25mm F1.8 lens in the world and aims it at daily carry, travel and street photography.

Optical design

According to SG-image the lens has 7 elements in 5 groups with a 58 degree angle of view. The 9-blade diaphragm runs from F1.8 to F16, and the spec sheet lists an automatic aperture, so there is no aperture ring. The minimum focus distance is 0.3 m with a maximum magnification of 1:10. SG-image says the design uses fewer moving parts to keep distortion and chromatic aberration low, which is a manufacturer claim. No special glass types are named on the product page.

Autofocus and handling

Autofocus is driven by a motor that SG-image describes as fast, accurate and quiet, aimed at street scenes and eye focus on portraits. Aperture is controlled from the camera. The lens has a 52 mm filter thread. SG-image's product title says it comes with a metal lens hood, and the same hood is also sold separately for this lens and the AF 35mm F2.2.

Build and size

The barrel is metal. The spec sheet lists a weight of about 145 g and dimensions of 67 mm diameter and 32 mm length, while the marketing text on the same page mentions 152 g and a depth of 34 mm, so there is a small inconsistency in the manufacturer's own figures.

Where it fits

For a manual alternative from the same maker see the SG-image MF 25mm F1.8, which is slightly heavier at 186 g. In the database, the 7artisans 25mm F1.8 is a comparable manual lens, and the 7Artisans AF 24mm F1.8 is an autofocus option for full frame mounts. SG-image also sells a Micro Four Thirds version of this lens as the AF 25mm F1.8 MFT.

Pros and cons

Pros

Very compact and light
Autofocus with a bright F1.8 aperture
9-blade diaphragm
Metal barrel
Available in black and silver for E, X and Z

Cons

No aperture ring
No stabilization, which is typical at this size
Manufacturer weight figures are inconsistent
No weather sealing mentioned
Limited independent test data so far

Verdict

The SG-image AF 25mm F1.8 is a small, light and inexpensive autofocus prime for APS-C cameras. It is a good fit for photographers who want a normal-view lens that disappears on the camera and do not need an aperture ring or weather sealing.

Technical Specifications

min focal length: 25 mm
max focal length: 25 mm
max f (min zoom): f/1.8
max f (max zoom): f/1.8
min. aperture: f/16
Elements: 7
Groups: 5
Weight: 145 g (0.32 lb)
Filter diameter: 52 mm
min focus distance: 30 cm (11.81 in)
Length: 32 mm (1.26 in)
Diameter: 67 mm (2.64 in)

Simulate depth of field and angle of view

Which cameras does the SG-image AF 25mm F1.8 fit?

The SG-image AF 25mm F1.8 is designed for APS-C sensors. On APS-C Sony E-Mount cameras its field of view equals 38 mm in full-frame terms. Full-frame bodies use it in APS-C (crop) mode, recording only part of the sensor and fewer megapixels.

Sony E-Mount cameras

Full frame (in APS-C mode):: Sony A7R VI, Sony A7 V, Sony FX2, Sony A1 II, Sony A9 III, Sony A7C II, Sony A7CR, Sony ZV-E1, Sony A7R V, Sony A7 IV, Sony A1, Sony FX3, Sony A7S III, Sony A7C, Sony FX6, Sony A7R IV, Sony A9 II, Sony FX9, Sony A7 III, Sony A7R III, Sony A9, Sony A7R II, Sony A7S II, Sony A7 II, Sony A7S, Sony A7, Sony A7R
APS-C:: Sony ZV-E10 II, Sony A6700, Sony FX30, Sony ZV-E10, Sony A6600, Sony A6100, Sony A6400, Sony A6500, Sony A6300, Sony A6000, Sony A5100, Sony A5000, Sony A3000, Sony NEX-5T, Sony NEX-3N, Sony NEX-6, Sony NEX-5R, Sony NEX-F3