Review of Viltrox AF 25mm 1:1.7 STM ASHP ED IF

Navigation

1. In short
2. Main Specifications
3. Assembly
4. Focusing
5. Firmware Upgrade
6. Image quality
7. Examples of photos (+source files)
8. Price
9. My experience
10. Video review
11. Results
12. User Comments
13. Add your review or question on the lens

In this review I will refer to the Viltrox AF 25mm 1:1.7 STM ASHP ED IF lens as 'Viltrox 25/1.7 AF'.

It's important: This review shows the Viltrox 25/1.7 AF version for FujiFilm mirrorless cameras with bayonet mount fujifilm x and with firmware version v1.02. At the same time, there are modifications of this lens for mirrorless cameras APS-C Nikon Z (Nikon DX) и Sony e-mount.

In short

Viltrox 25/1.7 AF is a modern lens for mirrorless cameras with a “cropped” APS-C sensor (coefficient crop factor Kf=1.5x). According to its parameters, the Viltrox 25/1.7 AF is a very attractive solution. First of all, the Viltrox 25/1.7 AF is designed for everyday photo and video shooting. The focal length on cameras with a cropped sensor and crop factor Kf=1.5x very convenient to use (EGF 37.5mm, which is very close to “classic 35mm lenses”).

Automatic focusing is performed by a stepper motor. The image quality is at a high level.

The Viltrox 25/1.7 AF is part of the Viltrox AIR series of lenses, which are lightweight and compact, with an excellent ratio prices and quality. This line also includes Viltrox models 20/2.8 (Full Frame), 35/1.7 (APS-C), 56/1.7 (APS-C), 40/2.5 (Full Frame). All three lenses for APS-C turned out to be very, very successful. Based on them, you can assemble an excellent set for most photo tasks (25, 35, 56 mm). Personally, I consider the Viltrox 25/1.7 models (from this review), 35/1.7, 56/1.7 some of the best solutions in their categories. In general, Viltrox approached the creation of three lines of optics quite competently: budget solutions of the AIR series (25, 35, 56 mm all with F/1.7), advanced solutions (13, 23, 33, 56 mm all with F/1.4) and professional solutions (27, 75 mm all with F/1.2).

The Viltrox 25/1.7 AF can be considered the “little brother” of a very successful model Viltrox AF23/1.4 AF. Unlike its older brother, the new Viltrox 25/1.7 AF is a lightweight and compact lens, with a lower price. The price of the new Viltrox 25/1.7 AF is low and amounts to approximately 160 dollars.

Such 22-23-24-25 mm lenses are in great demand and can be considered standard solutions for everyday photography tasks.

• for the system APS-C Sony E-mount Viltrox 25/1.7 AF lens is an alternative to the original autofocus similar lens Carl Zeiss Sonnar E 1,8 / 24 ZA T * (Sony SEL24F18Z).
• for the system APS-C Nikon Z (Nikon DX) Viltrox 25/1.7 AF lens is an alternative to the original autofocus similar lens Nikon Nikkor ZDX 24mm 1:1.7
• for the system APS-C FujiFilm X Viltrox 25/1.7 AF lens is an alternative to the original autofocus lens FUJINON ASPHERICAL LENS SUPER EBC XF 23mm 1: 2 R WR.

It's important: when searching and choosing autofocus optics for fujifilm x Use these very useful links:

• All autofocus lenses for FujiFilm X (original and third-party)
• All Viltrox Lenses

Alternatives

Below are all the fast 21-29mm autofocus lenses for mirrorless cameras with an APS-C sensor:

1. Sony 24/1.8 ZEISS (E)
2. Fujinon 23/1.4 XF R (X)
3. Fujinon 23/1.4 XF R WR LM (X)
4. Fujinon 23/2 XF R WR (X)
5. Fujinon 27/2.8 XF (X)
6. Fujinon 27/2.8 XF R WR (X)
7. Canon 22/2 (EF-M)
8. Canon 28/3.5 (EF-M)
9. Leica 23/2 (L/T/TL/CL)
10. Nikon 24/1.7 (Z)
11. Samsung 20/2.8 (NX)
12. Sigma 23/1.4 (X, E, L, RFS)
13. Viltrox 23/1.4 (E, X, Z, M)
14. Viltrox 27/1.2 (E, X, Z)
15. Viltrox 25/1.7 (E, X, Z)
16. Tokina 23/1.4 (E, X)
17. Yongnuo 23/1.4 (E, Z)
18. TTArtisan 27/2.8 (E, X, Z)
19. TTArtisan 23/1.8 (E, X, Z)
20. Sirui 23/1.2 (E, X, Z)
21. 7Artisans 25/1.8 AF (E, Z, X)
22. 7Artisans 27/2.8 (E, D52)
23. 7Artisans 27 / 2.8 II (Z, X, D39)
24. Ulanzi 27/2.8 (E)
25. Jintu 27/2.8 (E, X)
26. AstrHori 27/2.8 (X, Z)

Main technical characteristics of Viltrox AF 25mm 1:1.7 STM ASHP ED IF XF:

Review Instance Name	On the lens barrel: AF 25/1.7 XF Viltrox + data plate Near the front lens: AF 25mm 1:1.7 STM ASPH ED IF Image Size Ø28.4mm Ø52mm 0.3m/1ft On the box: Viltrox APS-C AF 25/1.7 AUTO FOCUS PRIME LENS X-mount
Basic properties	XF – the lens is designed for Fujifilm mirrorless cameras with X-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 H.R.I. - elements with an ultra-high refractive index Hd nano multi-layer coating – special enlightenment optics USB-port for firmware update Electronic focus ring Included hood Viltrox AIR – the lens belongs to the AIR lens line, which is characterized by lightness and compactness (these include models 20/2.8, 35/1.7, 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, plastic thread for filters
Focal length	25mm Equivalent Focal Length Sony E APS-C / APS-C Nikon Z (Nikon DX) / APS-C FujiFilm X is 37.5 mm
Zoom ratio	1 X (this is a fixed lens, it does not have a zoom)
Designed by	for cropped mirrorless digital cameras. Theoretically, the lens is suitable for all digital mirrorless cameras with interchangeable lenses and mount SONY E/FE и APS-C Nikon Z (Nikon DX) и APS-C FujiFilm X
Number of aperture blades	9 rounded petals
Tags	bayonet mount mark hood attachment mark
Diaphragm	from F/1.7 to F/16 without aperture control ring
MDF	0.3 meters, maximum magnification ratio 1:7
The weight	159 grams without lids according to my measurements (version under APS-C FujiFilm X). The model weighs exactly the same 56/1.7. 175 grams with two caps and a hood according to my measurements (version under APS-C FujiFilm X)
Optical design	11 elements in 9 groups, including 1 ED element, 2 aspherical elements and 2 ultra-high refractive index elements
Lens hood	Bayonet-type lens hood included in delivery
Manufacturer country	MADE IN CHINA (Made in China)
Period	Since March 2025 (this review was published on the day of the lens announcement)
Instructions	Included in delivery
Price	About $160, see current prices on Aliexpress

The actual aperture ratio (T-stage) is quite high, and is at the T/1.8 level.

Aperture F/1.7 approx. three stops wider F/5.6 aperture, which is used in some 'dark' standard lenses. Each step gives a twofold increase in aperture: 1.4 -> 2 -> 2.8 -> 4 -> 5.6. In numerical terms this means that the Viltrox 25/1.7 AF should be 11 times lighterthan stock lens FUJINON ASPHERICAL LENS SUPER EBC XC 16-50mm 1:3.5-5.6 OIS II, which at 35 mm focal length can use a maximum relative aperture of only 1:5.6. Calculating the difference in relative apertures (count aperture ratio) is done in an elementary way: (5.6*5.6)/(1.7*1.7)=11. The creative potential of such a lens is difficult to overestimate. Amateur photographers often use it as a portrait lens. Many people simply want a fast prime to complement their kit lens.

Assembly

The lens came for review new in its original box. The package does not include a USB cable for updating the firmware.

Viltrox 25/1.7 AF has metal mount. The focus ring is plastic, with veins, not rubberized.

The weight of the Viltrox 25/1.7 AF is approximately 170 grams. The lens body is made of plastic. The assembly is high quality. The lens feels good in your hands.

A durable plastic lens hood is included in the package. Bayonet type lens hood, snap-on reliably. The lens hood can be installed in the opposite direction (in transport mode), but in this case, access to the focus ring is partially lost.

The front and rear protective covers are plastic, massive, and easy to use.

The aperture consists of 9 blades. At F/1.7-F/4 the aperture takes a fairly round shape. The aperture works quickly and does not stick.

Focusing

The lens has a built-in STM focusing stepper motor. The motor runs very quietly.

The autofocus speed is fast. There is a slight noise/hum during focusing.

The focusing ring is plastic, wide, with veins. Electronic focusing ring, rotates very easily, has no extreme positions. The ring can be rotated with only one finger. There is virtually no lag in the electronic focusing ring.

During auto focus focus ring remains stationary.

Lens has internal focus, the front and rear lenses remain stationary during focusing. It is possible to use various filters without any problems.

The minimum focusing distance is 30cm and the maximum magnification ratio is 1:7.

The Focus breathing effect (changes in the viewing angle depending on the focusing distance) is very weak.

Firmware Upgrade

When connected to a computer, the lens is recognized as a 1.96 MB 'Viltrox DFU' drive. The drive contains a DeviceInformation.txt file - a text file with information about the lens and firmware, as well as the firmware file itself UserProfile.dat.

To update you should download the firmware file from the official website and copy it to the 'Viltrox DFU' drive, wait 5 seconds, then make sure that the text file shows the new firmware version. You may need to update information about your drive and/or connected devices. At the time of writing this review, there was no firmware update for this lens yet. It is worth noting that Viltrox constantly updates the firmware for its lenses.

Image quality

In general, the image quality of the Viltrox 25/1.7 AF is at a high level.

Resolution

• in the center of the frame at F/1.7 the lens is wonderful in terms of resolution
• there is a very slight drop in sharpness towards the edges of the frame at F/1.7
• after approximately F/2.8, the resolution is at a very high level across the entire field of the frame

Distortion

• small pincushion distortion
• the overall level of distortion is at a level typical for such lenses
• the nature of distortion is unified, easily corrected in the editor

Vignetting

• the overall level of vignetting is at a level typical for such lenses
• noticeable vignetting is observed only at F/1.7-F/2.5
• vignetting almost disappears at F / 2.8-F / 4
• vignetting is easily fixable in the editor

Aberration

• there is a small amount of chromatic aberration at open apertures
• there is a weak one friging (HA in the blur zone)
• aperture down to f / 4 significantly reduces the amount of HA

Rest

• the aperture opening at F/1.7-F/4 values ​​is quite round and smooth; at F/8-F/16 values ​​you can see regular nine-sided angles
• the lens does not tolerate backlight well
• in many scenes, the lens can create a pleasant / neutral bokeh

There is no lens profile for the lens in popular RAW converters, but most likely the profile will appear shortly or you can create it yourself.

Sample photos on APS-C

The camera used was FujiFilm X-T2 (24.3MP APS-C X-Trans CMOS III sensor). All photos in this review are shown without processing, according to the principles ZEROJPEG.

• Original RAW (FujiFilm '.RAF') photos can be view / download this link (50+ files, Google Drive gallery).
• The original photos in JPEG ('.jpg') format can be view / download this link (50+ files, Google Drive gallery).

Prices

Prices for Viltrox 25/1.7 AF on Aliexpress you can see at this link.

My experience

Viltrox 25/1.7 AF is simply excellent for its price. If you don’t take into account the work with backlight, then Viltrox 25/1.7 AF quite lives up to the level Carl Zeiss Sonnar E 1,8 / 24 ZA T * (Sony SEL24F18Z).

I also shot a lot of videos on the Viltrox 25/1.7 AF, including in very low-light conditions (Instatic Ecstatic dance in a dark hall and a fire show at night), the autofocus worked just fine.

Video review

Results

Viltrox 25/1.7 AF is an affordable standard fixed lens that copes well with various photographic tasks. Optical qualities are at a high level. One of the best similar lenses in terms of price and quality.

main advantages

1. internal focusing, electronic wide focusing ring
2. Quiet and fast stepping focus motor, tenacious autofocus
3. good/excellent build quality
4. USB port for firmware upgrade, easy firmware upgrade method
5. nine-petal diaphragm
6. modern complex optical design with special optical elements
7. nice / neutral drawing, which can be used as a good artistic technique during portraiture
8. high resolution across the entire frame field already at F/1.7
9. low level of vignetting and distortion
10. good value for money

main disadvantages

1. no AF/MF focus mode switch
2. no aperture control ring
3. no image stabilizer
4. the lens is poorly protected from environmental influences
5. other models have a wider viewing angle (focal length 22, 23, 24 mm)
6. mediocre resistance to backlight
7. tangible vignetting on f / 1.7

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Material prepared Arkady Shapoval.