Viltrox EF-NEX IV adapter (v1.9)

Viltrox has released a firmware update min-2019, and this posts talks about the updated performance of this adapter. I’ve specified my experience per lens, to give you a better overview on how each EF/EF-S lens performs in combination with this adapter. Be sure to check out my previous thought on this adapter here, as this is a continuation or update from the findings I reported in that post.

I’ve used this mount adapter exclusively in combination with the Sony A7 III, so all my thoughts presented here are related to this combination.

General remarks

So, after almost a year, we get a new firmware update for this adapter. While there’s a whole list of new lenses that have been tested and added to the compatibility list, the one thing that interested me the most was the improved CDAF functionality, improving the AF performance by allowing the adapter to make use of hybrid AF, combining CDAF and PDAF, just as native Sony FE lenses do!

Other EF to FE lens adapters have also had this update. Recently, Yongnuo, another Chinese camera accessory manufacturer, released their mount adapter, which includes this functionality (see Petapixel, for instance). I’m not a 100% sure, but I believed Metabones recently updated their mount adapter as well, also allowing for hybrid AF functionality.

When you download the updated firmware (link), you’ll be presented with two files: the regular v1.9 firmware and the ‘test-v041’ firmware, which includes the aforementioned hybrid CDAF functionality. I’ve exclusively used this ‘test’-firmware.

In addition to all the stuff written down below, this mount adapter allows you to mount EF or EF-S lenses to your Sony A7 camera. Please note that mounting an EF-S lens switches the camera to s35 mode, cropping the sensor to simulate an APS-C style camera. The adapter was able to control the aperture of all lenses that I’ve tested. The correct focal length is sent to the camera’s IBIS system, allowing for automatic sensor stabilization that adapts to the focal length of the lens. For instance, zooming the Canon EF 17-40 f/4 L USM to 17mm changed the IBIS to 17mm, while zooming to 35mm changed the IBIS to 35mm. This means that if your Sony camera supports IBIS, it automatically chooses the correct setting for the attached Canon lens.

Compared to the previous version of the firmware, v1.8, the adapter has become a lot more stable. I’ve never had the camera lock up with this firmware, which is in stark contrast to my experiences with firmware v1.8, where the camera-adapter-lens combination would lock-up and freeze every 100 or so pictures.

However, if you change settings related to AF in the camera, you need to reboot the camera and remount the lens-adapter combination for the change to occur. For instance, I changed the focus speed settings from normal to fast. This caused the camera to cease operating: even though the EVF and monitor still displayed a live feed, I couldn’t change camera settings like aperture or shutter speed. Rebooting in this case was not enough, and this caused the camera to boot up with a black screen (even though the lens cap was off). After uncoupling the mount adapter from the body and re-attaching, my camera worked as expected again, with the changed AF settings successfully changed.

Canon EF 17-40 f/4 L USM

This lens combination works wonderfully on the Sony A7 III. The camera automatically changes the IBIS system based on the focal length of the lens. AF works better than I expected in both photo and video, delivering a sharp and L-level quality image.

Face-detection works in both photo and video mode. In photo mode, it even detects the eyes and draws a green square around them, indicating that the eyes are in focus. However, one consistent finding that I experienced is that face-detection only works when the subject is in the center of the frame. When a subject is to the side, the camera detects a face, but is unable to achieve focus. Instead, the lens keeps hunting back and forth and ultimately gives up. The same is true for tap-to-focus: it only works when it’s in the center of the frame. This finding holds true for both photo and video.

The AF motor makes a little noise when shooting video. It is noticeably louder than my native Sony FE 28-70 kit-lens. However, if you’re in a somewhat noisy environment, the noise this lens makes is insignificant. For instance, when I use my Rode Videomic Pro, focussing noise is barely noticeable in the video.

AF is fairly quick, quick enough for my taste. I’m unable to compare it to how this lens performs on a native Canon camera, but I suppose it’s quicker. As far as I’m concerned, it’s quick enough for me, and I’ve not missed a shot both in video and photo due to this lens not focussing fast enough. You can take a listen to a recording of the A7 with this lens, where you can hear the AF motor, when audio sensitivity is set to 31 (link).

Canon EF 24-105 f4 L IS USM

I’ve used this lens after using the EF 17-40 for a couple of weeks, so naturally I’ve compared it to the performance of that lens.

First and foremost, the focussing system in video is significantly slower. I’ve changed the focussing speed to fast (and causing the camera to cease operating properly, as explained above, requiring a re-mounting of the lens in order to relieve this). Setting the speed to fast still makes this lens acquire focus a bit slow. It is significantly slower than using the native FE 28-70 kit-lens, and is a little bit too slow for me when you need to change focus form very close to very far. However, I don’t think you’ll need to perform such a focus move, as with my video shooting I usually need the lens to perform only slight focus adjustments, as with tracking a face or subject along a background. For photo however, focus is achieved quickly enough, making this a non-issue for photo.

Just as with the EF 17-40, face detection works only when the face is in the center of the frame, both with video and photo.

AF is noisier than the EF 17-40, which was noisier than the native FE 28-70. I’ve not had enough experience with video shooting with this lens to form an opinion on whether it is usually in real-life scenarios. Also, mind you, there’s the internal IS that works alongside the IBIS system, which also makes a significant amount of noise. Here’s the noise from the AF and IS system when setting the audio sensitivity to 31 (link).

Canon EF 70-300 IS USM

On the day the firmware was released, I made a video showing off the AF-C capabilities of my new-to-me Canon EF 70-300 IS USM tele-zoom lens. I’m not sure if this combination uses hybrid AF or regular CDAF, and I’m not sure if I’m able to tell whether this is used at all! However, this should give you an indication of the usability of AF in video using a Sony A7 III and the Canon EF 70-300 IS USM. Check out the YouTube test footage here!

Last weekend, I used this lens to shoot racing cars on a circuit nearby. I took a spot near the track on top of a building, allowing me to chase the cars as they moved through the final two corners before accelerating along the straight. I was able to track most cars for about 5 seconds. Using the Hi+ drive setting during photo mode, allowing me to shoot photos with 10 fps, all the pictures I took where sharp and in focus. Take a look at the GIF I made from the pictures I took.

When I tried to shoot a video of the cars moving by, sometimes the lens was unable to achieve focus for the 5 seconds. In other cases, focus was achieved during the first second, allowing me to track the car along the corners while perfectly in focus using AF-C. A tactic I uncovered here was starting out at 75mm, tracking the car and zooming in along the way to 300mm to get the car to be in focus.

Canon EF-S 55-250 IS

This is the first iteration of this lens, that does have IS but it’s not the II or the STM version.

This lens presents an affordable option for the EF-S system, and matches neatly with the EF-S 18-55 kit-lens. However, for a full-frame camera such as the A7 III, this lens is a lot less sensible.

First, this lens shows a heavy black border when the camera is not set to s35 mode. As this crops the sensor heavily, the quality goes down noticeably. Secondly, to make things worse, the autofocus is very slow on this combination. It takes ages for this lens to achieve focus, making it almost unusable when trying to use it in practice.

Finally, on a positive note, the IS system works neatly in combination with the A7 III’s IBIS.

In my opinion, taking into consideration the value of this lens, I would choose the Canon EF 70-300 IS USM over this lens anytime. Even thought that lens is bigger and heavier, the AF system works faster and better, and image quality is also improved.

Tokina 11-16 f/2.8 AT-X

The full name of the lens I used is the Tokina AT-X PRO SD 11-16 F2.8 (IF) DX II. This is relevant as there have been a number of variants of this lens produced.

Unfortunately, the copy of the Tokina that I used had a malfunction with AF, where the AF system would not engage in any way. This means that I have no idea how the PDAF or CDAF functions on this camera-adapter-lens combination. I did, however, discover some other interesting findings.

First, as does with most lenses, the lens’ focal length is communicated with the IBIS system. This is relevant because even though most original Canon lenses allow for this functionality, this is the first third-party manufacturer lens that communicates the focal length. You can rest assured that the image of this lens combination is being stabilized by the A7 III IBIS system.

Secondly, even though this lens was made for an APS-C camera, the Sony A7 III does not automatically change to s35 mode, as it does with native EF-S lenses. This results in the outline of circle against a black background when I first turned on the lens at 11mm. This heavy vignetting is unusable, you really need to manually set the camera to s35 in order to use this lens at 11mm. However, and here it gets interesting: at 16mm there’s no vignetting anymore, when the camera is set to FF mode. That means that you can use this lens as a 16mm F2.8 full-frame lens at 16mm! If you would set the camera to s35, the widest you can get is 11 * 1,5 = 16,5mm with a cropped sensor. Setting the camera to full-frame and zooming to 16mm will get you a slightly wider FOV and allow you to use the full sensor of the camera!



  • Cheaper than both the Sigma MC-11 and Metabones adapters
  • Firmware can be upgraded and it still being updated by Viltrox as of July 2019
  • Contrast AF (hybrid) in video mode
  • Both contrast AF and phase AF in photo mode
  • Compatible with EF-S lenses
  • Communcation with camera: both type (APS-C or FF lens), lens name and focal length are communicated to the body, so you have IBIS functioning as expected, as well as correct EXIF information


  • Phase AF is not usable for video: AF-C will not be as smooth and stable as native Sony lenses
  • Some EF/EF-S lenses are not supported
  • Non-STM lenses can make a lot of noise when focussing (although this is not a con of this adapter, but concerns most Canon EF lenses)

7 thoughts on “Viltrox EF-NEX IV adapter (v1.9)

  1. Thanks for the very detailed review. Your article helped me a lot. Now I wouldn’t hesitate to go to the store to buy a Viltrox IV mount. I’ve seen a lot of YouTube reviews about this mount but yours really makes me feel safe and confident. Wishing you a healthy, lucky and successful New Year!!!


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