Review of Viltrox AF 20mm 1: 2.8 STM ASPH ED IF (Air, Sony FE, Nikon Z)

Navigation

1. In short
2. Main Specifications
3. Assembly
4. Focusing
5. Firmware Upgrade
6. Image quality
7. Sample Photos
8. My experience
9. Price
10. Video review
11. Conclusion
12. User Comments
13. Add your review or question on the lens

In this review I will refer to the Viltrox AF 20mm 1:2.8 STM ASPH ED IF lens as the Viltrox 20/2.8 for short.

Important : This review shows the Viltrox 20/2.8 lens for Sony mirrorless cameras with the Sony E-mount and firmware version v1.1.2. A version of this lens for Nikon Z mirrorless cameras is also available . UPDATE: A version of this lens for the Leica L mount was released in September 2026.

Important : Viltrox 20/2.8 can be found with a white body color.

In short

The Viltrox 20/2.8 is a modern lens for full-frame mirrorless cameras with the Sony E/FE and Nikon Z mounts . It features internal autofocus and operates quietly thanks to a stepping motor. Optically balanced! Seven aperture blades, a light weight (only 170 grams!), compact dimensions, and a complex optical design, the Viltrox 20/2.8 is priced at just $160.

Viltrox 20/2.8 is a best seller.

Important : When searching for and selecting autofocus lenses for Sony E-mount Full Frame, please use these very useful links:

• All autofocus lenses for Sony E/Sony FE (original and third party)
• All autofocus lenses for Nikon Z (FX/DX) (original and third party)
• All lenses felttrox

Main technical characteristics of Viltrox AF 20mm 1:2.8 STM ASPH ED IF:

Review Instance Name	Near the front lens: Viltrox AF 28mm 1:2.8 STM ASPH ED IF IMAGE SIZE Ø43.3 Ø52mm 0.19m/0.62ft On the body: Viltrox AF 28/2.8 FE + identification plate
Basic properties	FE (Sony Full FCopper E-mount) - designed for Sony E-mount mirrorless full-frame cameras (Sony E mount) AF (Acles Focus) - the lens supports auto focus STM (Scarpets Motor) - focusing stepper motor IF (Iinternal Focusing) - internal focus ED (Extra Low Dispersion) - low dispersion elements in the optical scheme ASPH (Aspherical) - aspherical elements in the optical design Elements with ultra-high refractive index in the optical scheme USB-port for firmware update Electronic focus ring Lens hood and soft case included Viltrox AIR – the lens belongs to the AIR lens line, which is characterized by lightness and compactness (these include models 25/1.7, 35/1.7, 56/1.7, 40/2.5, 50/2) Protective water-repellent coating on the front lens Available in two body colors Important: lens from a third-party manufacturer, which imposes some restrictions on its use
Front Filter Diameter	52 mm
Focal length	20 mm, EGF Sony E APS-C / APS-C Nikon Z (Nikon DX) is 30 mm
Zoom ratio	1 X (this is a fixed lens, it does not have a zoom)
Designed by	for Sony NEX/Sony ALPHA/Sony ILCE mirrorless cameras with E-mount (sometimes listed as FE)
Number of aperture blades	7 rounded petals
Tags	bayonet mount mark and hood mount mark
Diaphragm	F / 2.8 to F / 16
MDF	0.19 meters, maximum magnification ratio 1:5.9
The weight	157 grams according to my measurements without covers and hood (version for Sony E)
Optical design	10 elements in 8 groups. The scheme includes 2 low dispersion elements 1 ultra high refractive index element 2 aspherical elements The image of the optical scheme is clickable to enlarge
Lens hood	Bayonet type, model Viltrox PL-56
Manufacturer country	MADE IN CHINA (Made in China)
Period	from November 2023
Firmware	The lens in the review used firmware v1.1.2
Prices	Look at Gear with free shipping

The actual aperture ratio (T-stage) is quite high, and is at the T/2.9 level.

Assembly

The lens came for review new in its original box.

The Viltrox 20/2.8 has a metal bayonet mount . The focusing ring is wide and plastic, not rubberized. The lens feels good in your hands. The Viltrox 14/2.8 has a plastic body to minimize weight. It weighs approximately 160 grams. The front filter diameter is only 52 mm.

The barrel features a bayonet mount and a quick-release hood attachment point. The lens uses a small plastic Viltrox PL-56 hood, which fits into special grooves near the front element. The hood can be mounted in reverse for transport, allowing minimal access to the focusing ring. The front element has a special protective coating that repels water, dust, and dirt.

The lens has a USB TYPE C connector for connecting to a computer.

Important : The lens initializes after the camera is put into sleep and then woken up, as well as when the camera is turned on. During initialization, the lens adjusts the aperture from f/16 to the specified value. The lens also sets a specific focusing distance.

Important : When the lens is detached from the camera, or when the camera is turned off, or when the camera is in 'sleep' mode, the aperture blades are always closed to F/16.

Important: Initialization takes about one and a half seconds, which makes it difficult to quickly turn on the camera and take the first photo.

Focusing

The Viltrox 20/2.8 uses a stepping motor ( STM ) for focusing . Autofocus should work with all Sony E/FE-mount cameras.

Important : The Viltrox 20/2.8 will only work correctly with modern Sony E-mount cameras. Some issues may arise with older models. For example, on the Sony NEX-F3 (2012) and Sony a3500 (2014), the Viltrox 20/2.8 autofocus is noticeably slower. It's likely that a camera with phase-detection AF is required for the Viltrox 50/2 to work correctly. For example, on the Sony a7, the lens works correctly in still mode.

The focusing speed is average, closer to high, quite comfortable for work. I didn't have any problems focusing on the Sony a7. After the lens loses precise focus, refocusing is performed quite quickly.

Important : In challenging shooting conditions, as well as when shooting dynamic scenes, focusing performance with the Viltrox 50/2 can be noticeably worse than with similar original lenses. Even in simple shooting conditions, autofocus performance with the Viltrox 20/2.8 will vary greatly depending on the camera used. New firmware updates for the lens may improve this situation over time.

Autofocus is quiet , but there is still a slight hum from the focus motor.

The lens uses an electronic focusing ring . The focusing ring is wide, not rubberized, and rotates approximately 270 degrees in manual focusing mode . When reaching its extreme positions, the ring doesn't stop but continues to rotate. Manual focusing is quite convenient . The focusing ring rotates easily. I didn't observe any lag when changing direction. The electronic focusing ring is well-designed and responds more to the rotation angle than to the speed of its rotation.

During automatic focusing, the focus ring remains stationary , but can be rotated freely without affecting focus (provided the camera's menu is set to the standard AF mode 'Autofocus', not 'MF' or 'DMF'). During manual focusing, some cameras display a scale indicating the approximate focusing distance.

The lens features internal focusing ; the front element remains stationary during focusing. Various filters can be used without any problems.

The minimum focusing distance is 19 cm.

The 'Focus Breathing' effect (changes in viewing angle during focusing) is small; when focusing towards the MDF, the viewing angle decreases.

There are no useful marks on the focusing distance, depth of field, or anything else on the lens.

Focus shift (shift-focus) was not noticed during operation and testing.

Firmware Upgrade

On the mount side, the Viltrox 20 / 2.8 has a USB port that can be used to update the software (firmware / firmware) of the lens.

The connection uses a common USB TYPE C port (many mobile phones use this type). A cable is included in the package. The latest firmware for the lens can be found here.

The firmware update will most likely improve the compatibility of the lens with new cameras, improve the autofocus performance, and eliminate some other disadvantages.

Important: To update the lens firmware (software):

1. Turn off the camera, detach the lens
2. Connect the lens to a computer using a USB cable. The lens should be identified as a 'Viltrox DFU' drive
3. Find the file 'DeviceInformation.txt' on this drive and check the current firmware version (the firmware version may not need to be updated)
4. Copy the firmware file to the 'Viltrox DFU' folder (file with the '.dat' resolution, which must be downloaded from the official Viltrox website). Wait for the end of copying
5. After copying is complete, the 'Viltrox DFU' drive will automatically shut down and reconnect after 5 seconds (approximately), after which you can check the current firmware version
6. Disconnect cable
7. Attach the lens to the camera
8. Turn on the camera

Image quality

The Viltrox 20/2.8 has its quirks, but is overall good.

Sharpness

• good sharpness at open aperture in the center of the frame
• very good resolution in the center of the frame is achieved after f / 4
• there is a slight drop in sharpness in the far corners of the frame
• there is a very weak coma

Distortion

• the distortion is weak but complex
• It is difficult to correct distortion manually

Vignetting

• strong vignetting at F / 2.8
• vignetting almost completely disappears at values ​​after F/8
• vignetting decreases with focus towards MDF
• vignetting is strongest when focusing at infinity

Aberration

• the lens creates a small amount of chromatic aberrations, both longitudinal and transverse
• frigging disappears after F/4

Rest

• the star ray effect is well expressed (14 rays) at apertures after F/5.6
• the lens works well in backlight, only in the most difficult conditions can you get flares that significantly spoil the picture
• the bokeh is nice

Full Frame Photo Samples

The cameras used were a Sony a7 (24 MP Full Frame Exmor HD CMOS sensor) and a Sony α3500 (20 MP Sony Exmor APS-C HD CMOS sensor).

• Original photos in RAW format (Sony '.ARW' 12-bit compressed, only Sony a7) can download / watch this link (Google Drive, 50+ photos).
• Photos in JPEG format ('.JPG' with Sony a7 и Sony a3500) can download / watch this link (Google Drive, 70+ photos).

My experience

Viltrox 20/2.8 is a simple and straightforward ultra-wide-angle lens. Balanced, lightweight and affordable. Personally, I was a little disappointed with the lens's vignetting and complex distortion, which are very important qualities for an ultra-wide-angle lens.

There aren't many similar lenses: Tamron 20mm F/2.8 Di III OSD M1:2 (Model F050) , ZEISS Distagon 2.8/18 T* (Batis 2.8/18) , Samyang Remaster Slim 21/3.5 , Samyang AF 18/2.8 FE . The rest are either a stop brighter or have a focal length of 24-28 mm. At one time, 20/2.8 lenses were more common than they are now (remember, for example, the Nikon AF Nikkor 20mm 1:2.8D ). The Viltrox 20/2.8 is the most affordable similar autofocus ultra-wide lens for Sony FE/Nikon Z.

The Viltrox 20/2.8 is also great for cropped cameras. It can be an alternative to the cropped Sony E 2.8/20 ( SEL20F28 , around $350). It looks great on my tiny Sony NEX-F3 camera.

The entire Viltrox lens series deserves due attention.

Price

The Viltrox 20/2.8 costs around $160 , making it a very attractive offer. You can check prices for the Viltrox 20/2.8 on the Pergear website , including free shipping.

Video review

Conclusion

Viltrox 20/2.8 – lightweight, compact, with a stepping motor for focusing and good optical performance.

10 main advantages:

1. low cost (about 160 $)
2. good assembly, metal bayonet mount, bayonet hood included, protective coating of the front lens
3. light weight
4. compact sizes
5. stepping focus motor fast enough
6. internal focusing, fixed focus ring during auto focus
7. electronic focusing ring, continuous manual focus control
8. USB port for firmware upgrade
9. modern complex optical design, which includes 8 special optical elements
10. high resolution across the entire frame starting at F/5.6

10 main disadvantages:

1. there are no additional tags (depth of field, focusing distance, etc.)
2. there is no rubber seal for the bayonet mount (although it is stated that the lens is protected to a certain extent)
3. no AF/MF focus mode switch
4. no aperture control ring
5. focusing does not work well with older Sony XEX/ALPHA cameras without phase detection focus sensors
6. mediocre aperture (in the background Sony FE 20/1.8G, Sigma 20/2C DN, Tokina FE 20/2)
7. only 7 aperture blades
8. sometimes there is an excessive amount of glare when working in difficult backlighting
9. complex distortion
10. strong vignetting at F / 2.8

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