Review of Viltrox AF 40mm 1:2.5 STM ASPH ED IF

Navigation

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

In this review I will call the Viltrox AF 40mm 1:2.5 STM ASPH ED IF lens for short Viltrox 40 / 2.5.

It's important: This review shows the Viltrox 40/2.5 version for Sony mirrorless cameras with a mount Sony e-mount and with firmware version v1.01. At the same time, there is a modification of this lens for mirrorless cameras of the system Nikon Z.

UPDATED: at the end of September 2024, a version of Viltrox 40/2.5 with a white body color appeared.

In short

Viltrox 40/2.5 – a modern lens for full-frame mirrorless cameras with a bayonet mount Sony E / FE и Nikon Z. It has internal automatic focusing and operates quite quietly thanks to the stepper focusing motor. Optically good, sharp in the center of the frame already from F/2.5, build quality is at a high level. Among the shortcomings, we can only highlight mediocre, as for a fixed lens, aperture.

Viltrox 40/2.5 is designed to serve as an alternative to the original lenses Sony FE 2.5 / 40 G и Nikon Nikkor Z 40mm 1: 2  / Nikon Nikkor Z 40mm 1: 2 SE.

40mm is not the most common focal length. Such a lens belongs to “standard” lenses - lenses whose focal length approximately corresponds to the diagonal of the frame for which the lens is designed. Near the front lens of the Viltrox 40/2.5 there is the inscription “IMAGE SIZE Ø43mm” (frame size/image diagonal 43mm). 40 mm focal length approximately corresponds to 43 mm frame diagonal. This focal length gives a perspective close to the human eye, which simplifies the shooting process, and the resulting result has a “natural” appearance.

The price of Viltrox 40 / 2.5 is around $ 150.

It's important: when searching and choosing autofocus optics for Sony E-mount Full Frame, use these very useful links:

• All autofocus lenses for Sony E / Sony FE (original and from third-party manufacturers)
• All Viltrox Lenses

Main technical characteristics of Viltrox AF 40mm 1:2.5 STM ASPH ED IF:

Review Instance Name	Near the front lens: AF 40mm 1:2 STM ASPH ED IF IMAGE SIZE Ø43mm Ø52mm 0.34m/1.12ft On the body: Viltrox AF 40/2.5 FE + identification plate
Basic properties	FE (Sony Full Fcopper E-mount) - designed for Sony E-mount mirrorless full-frame cameras (Sony E mount) AF (Auto Focus) - the lens supports auto focus DF (DIGITAL Full Frame) - lens for full-frame cameras 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 20/2.8, 56/1.7, 40/2.5) Important: lens from a third-party manufacturer, which imposes some restrictions on its use
Front Filter Diameter	52 mm
Focal length	40 mm, EGF for cameras Sony E APS-C / APS-C Nikon Z (Nikon DX) is 60 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 / 2.5 to F / 16
MDF	0.34 meters, maximum magnification ratio 0.14 X (1: 7)
The weight	169 grams according to my measurements without covers and hood (version for Sony E)
Optical design	10 elements in 6 groups. The scheme includes 1 low dispersion element 3 ultra-high refractive index elements 1 aspherical element 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 April 25, 2024 for Nikon Z. From August 26, 2024 for Sony E.
Firmware	The lens from the review used firmware v1.01 from 2024.07.16
Prices	View on AliExpress

The actual aperture ratio (T-stage) is quite high, and is at the T/2.8 level.

Assembly

The lens came for review new in its original box.

Viltrox 40 / 2.5 has metal mount. The focusing ring is wide, not rubberized, plastic. The lens feels good in your hands. The Viltrox 40/2.5 is specially designed with a plastic housing to minimize its weight. The weight of Viltrox 40/2.5 is about 150 grams. The diameter of the front filter is only 52 mm.

There is a bayonet mount mark on the body and a mark for quick attachment of the hood. The lens uses a small plastic hood Viltrox PL-56, which must be fixed in special slots located near the front lens of the lens. The hood can be installed in the transport mode with the reverse side, in this position, access to the focusing ring is practically not lost.

The lens has a connector USB TYPE C To connect to a computer, the package does not include a corresponding cable.

It's important: The lens is initialized after the camera goes to sleep and wakes up, and when the camera is turned on. During initialization, the lens changes its aperture from F/16 to the specified value. The lens also sets a certain focusing distance.

It's 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 down 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

For focusing, the Viltrox 40 / 2.5 uses stepper focus motor STM (Stapping Motor). Auto Focus should work with all Sony cameras with an E / FE mount.

Very important: Viltrox 40/2.5 will only work correctly with modern cameras with a Sony E mount. Certain difficulties may arise with older models. For example, on cameras Sony NEX-F3 (2012) and Sony a3500 (2014) Viltrox 40/2.5 auto focus works very poorly. Most likely, for the Viltrox 40/2.5 to work correctly, you need a camera with phase focusing sensors. For example, on Sony a7 The lens works correctly in photo 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.

It's important: in difficult shooting conditions, as well as when shooting dynamic scenes, the focusing quality with the Viltrox 40/2.5 can be noticeably worse than with original similar lenses. Even in simple shooting conditions, the tenacity of autofocus with the Viltrox 40/2.5 will greatly depend on the camera used. Perhaps over time, new firmware for the lens will improve this situation.

Auto focus silent.

Lens uses electronic focus ring. Focus ring not rubberized, wide, in manual focus mode rotates approximately 270 degrees. When extreme positions are reached, the ring does not abut, but continues to rotate. Manual focus is enough conveniently. The focus ring rotates easily. I did not observe any delay (lag) when changing the direction of rotation. The electronic focusing ring is well implemented and responds more to the angle of rotation than to the speed of its rotation.

During auto focus focus ring remains stationary, however, it can be freely rotated without any effect on focus (if the normal AF mode 'Autofocus', not 'MF', and not 'DMF' is enabled in the camera menu). During manual focusing, a scale of approximate focusing distances appears on the display of some cameras.

The lens has internal focusing, the front lens remains stationary during focusing. It is possible to use various filters without any problems.

The minimum focusing distance is 34 cm, while the maximum magnification for macro photography of 1: 7 can be obtained.

'Focus Breathing' effect (changes in viewing angle during focusing) small and almost invisible.

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 40 / 2.5 has a USB port that can be used to update the software (firmware / firmware) of the lens.

The common USB TYPE C port is used for connection (many mobile phones use this one). The package does not include a USB cable. To connect, I used a USB cable from my smartphone. 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 PFU' 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 PFU' folder (file with '.dat' permission, which must be downloaded from the official Viltrox website). Wait for the end of copying
5. After copying is complete, the 'Viltrox PFU' 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 40 / 2.5 easily handles the 20MP APS-C type Exmor CMOS sensor at the heart of the camera Sony α3500 (ILCE-3500)... The pixel density is higher than that of Sony a7r II or a7r III. The 24 MP sensor of the Sony a7 is also good.

Sharpness

• good sharpness at open aperture in the center of the frame
• very good resolution in the center of the frame is achieved at f / 4-f / 8
• there is a very slight drop in sharpness in the far corners of the frame
• there is coma, especially at close focusing distances, coma decreases significantly at values ​​after F/5.6

Distortion

• distortion is weak, barrel-shaped
• It’s easy to correct distortion manually

Vignetting

• weak vignetting at F/2.5
• vignetting almost completely disappears at values ​​after F/4
• vignetting decreases with focus towards MDF
• vignetting is strongest when focusing at infinity

Aberration

• the lens creates a fairly small amount of chromatic aberrations, both longitudinal and transverse
• there is a noticeable frigging (the color of the contrasting areas of confusion is green and purple), the frigging is significantly reduced with aperture

Rest

• the star ray effect is well expressed (14 rays) at apertures after F/8
• the lens works well in backlight, only in the most difficult conditions can you get flares that significantly spoil the picture
• The bokeh has a slightly “bubble shape”

Sample Photos

Camera used Sony a7 (24 MP Full Frame Exmor HD CMOS sensor).

• Original photos in RAW format (Sony '.ARW' 12-bit compressed) can be download / watch this link (Google Drive, 50+ photos).
• Photos in JPEG '.JPG' format can be download / watch this link (Google Drive, 100+ photos).

My experience

I shot with the Viltrox 40/2.5 for about three weeks, testing it in different conditions and shooting genres. I was pleased. Viltrox 40/2.5 has its own “pattern”. Light, sharp, with an “interesting” field of view angle. Viltrox 40/2.5 is somewhere between 35 weave and 50 weave. Survived a long shoot in light rain (photo from the festival).

Price

The price for Viltrox 40/2.5 is about 150 dollars, which is a very attractive offer. View prices for Viltrox 40/2.5 on Aliexpress you can follow this link.

Video review

Results

Viltrox 40/2.5 is a lens with a good price-quality ratio. It is lightweight, has good optical performance and a quiet focusing motor.

10 main advantages:

1. low cost (about 150 $for example like Nikon Nikkor Z 40mm 1: 2 SE costs about $ 300)
2. good build, metal bayonet, bayonet hood included
3. focusing stepper motor, fast enough and quiet
4. internal focusing, fixed focus ring during auto focus
5. electronic focusing ring, continuous manual focus control
6. USB port for firmware upgrade
7. modern complex optical design, which includes 8 special optical elements
8. good sharpness in the center of the frame already with F / 2.5
9. own characteristic “pattern”
10. a focal length that is rare for a prime lens

10 main disadvantages:

1. limited selection of cameras with full compatibility. Critical: Lenses are not recognized by some older camera models. Updating the firmware does not change the situation. Most likely the lens will only work with cameras that have phase focus sensors
2. poor auto focus behavior during video shooting on some cameras
3. there are no additional tags (depth of field, focusing distance, etc.)
4. no rubber mount for the mount (although the lens is claimed to be protected)
5. there is no AF/MF focus mode switch (for example, there is Sony FE 2.5 / 40 G)
6. no programmable FN button (for example, there is a cheap Yongnuo 35/2 DF DSM)
7. aperture F/2.5 (for example, Nikon Nikkor Z 40mm 1: 2 SE the maximum aperture is almost one stop wider)
8. there is no aperture control ring (for example, there is Sony FE 2.5 / 40 G)
9. only 7 aperture blades (for example, Nikon Nikkor Z 40mm 1: 2 SE there are 9 of them)
10. sagging sharpness in the corners and edges of the image at F / 2.5

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Material prepared Arkady Shapoval.