Viltrox EF-NEX IV adapter (v1.8)

Here, I present my experiences with the Viltrox EF-NEX IV adapter, for adapting Canon EF and EF-S lenses to my Sony E-mount camera.

UPDATE (20-08-2019): There’s a new firmware out, v1.9, which includes a test firmware update improving CDAF performance, stating that CDAF “…now simulates the hybrid focus of the original lens, improving focus performance. (source)” After using this firmware v1.9 during my summer holiday, I’ve written up my experiences here.

UPDATE (18-05-2019): I’ve added a section (it’s just before the conclusion) concerning this adapter causing the camera to freeze! However, since the v1.9 update, I’ve had no problems with the adapter causing the camera to stop functioning.

The box looks and feel quite luxurious

I bought my copy from an online camera store in the Netherlands (link), but you can also buy this adapter directly from China (link). It should cost you around €130 or $150.


Coming from a background as a Canon shooter (see my background), I still had a number of old Canon lenses. Furthermore, some of my friends still shoot Canon, and I was looking for a way to be able to use these lenses on my new Sony A7 III.

After the unboxing…

As I started looking into what’s out there, I found two relatively expensive options: the Sigma MC-11 or one of the various Metabones adapters. Because I didn’t plan on using Canon EF lenses in my adventures, but just wanted to try out if and how I could use EF lenses in this new Sony E ecosystem, I opted for the cheaper alternative: the Viltrox EF-NEX IV.

Canon EF 28-105 3.5-4.5 USM with Viltrox EF-NEX IV adapter attached

Even though Viltrox has used the ‘NEX’ moniker for this product, it is aimed solely on the full-frame E-mount cameras. One would assume that ‘NEX’ would refer to the APS-C line of E-mount cameras, but this is not the case. Rather confusingly, Viltrox also offer a product called the EF-E mount adapter, which is similar to a speedbooster, and would only fit on APS-C E-mount cameras, or force FF E-mount cameras in their APS-C/Super35 mode. This makes no sense to me at all…


However, apart from the confusing naming convention, let’s move on to what this thing can do. As you would expect, you can mount Canon EF lenses to this adapter, which you can then mount on your FF Sony E-mount camera. Thanks to the electronic communication between the adapter, lens and body, you can change lens settings like aperture. Funnily enough, you can even override the AF/MF switch in some cases!

Electronics allow for aperture control and auto focus

Physically, the adapter comes with a tripod adapter, that thankfully can be removed easily. I’m not sure what the purpose of this mounting system is: if you have a lens that needs to be supported, why not supported the lens directly with its tripod collar? It might be just me, I’ve only used such big and heavy lenses on a small number of occasions.

The tripod mount comes off

Both EF and EF-S lenses work on this adapter. More interestingly, when you mount an EF-S lens, the adapter sends this information over to the camera. If you have APS-C/Super35 mode set to auto, mounting an EF-S lens with this adapter will tell the camera that a crop-factor lens has been attached, which crops the sensor, just as would mounting a native APS-C lens!

Moreover, the EXIF information of the EF lens is communicated over to the body. As such, when you view your pictures in Lightroom, you can see exactly which lens you used, including the exact focal length!

Loupe info shows a Sony camera with a Canon lens

Finally, this focal length data is also sent through to the IBIS system, at least it does on the A7 III. This means that the IBIS system ‘knows’ the current focal length, and can adjust accordingly. When mounting MF lenses, you have to specify to your IBIS system what focal length you’re using, as the camera has no electronic communication with the lens. With this adapter however, this information is passed on. So if you’re camera supports IBIS, all your non-IS Canon EF lenses now functionally have IS!

This adapter has two interesting features that set it apart from other adapters. One, it has a USB port, that allows for upgrading of the firmware. In 2018, Viltrox has released a whole lot of firmware upgrades for this adapter. With each of these updates, ‘support’ for new lenses is added. Although, I’m not sure what that means, as the lens that I use the most with this adapter, the Canon EF-S 10-18 IS STM, is not on the list, but it works just fine!

Cheap UWA solution for the A7

Finally, next to the USB port, there’s a CDAF <-> PDAF switch. As far as I have discovered, this switches between Contrast Detection Auto Focus and Phase Detection Auto Focus. If you’re unfamiliar with the difference between these two (as I was), you can watch this very helpful and informative video by Gerald Undone. If I understand correctly, the more expensive Metabones adapter also supports both AF modes, although they call it green and advanced mode. Green mode would be CDAF, and advanced mode would probably be PDAF, but as I’ve never used this Metabones adapter, I can’t say for sure.
One quirky property of this adapter is that when you change AF mode, you have to disconnect the adapter from the body. I’ve tested this, and if you don’t unmount and remount the lens + adapter combo, it does not function properly.

The choice for either CDAF or PDAF depends on what you want to do. For video, you should definitely go with CDAF. In this mode, you can actually use your lens just as you would a native Sony lens. AF-C is supported, and even face detection works! While AF is not as reliable or quick as a native Sony lens, it is quite usable. Sometimes however, focus is not immediately achieved, and the lens starts hunting. PDAF, on the other hand, is not usable at all in video: all of the lenses I have tested, some of which were on the ‘supported’ Viltrox list, keep hunting for focus. When they stop focussing, things are horribly out of focus, with no way of getting them back in focus. The PDAF setting on this adapter is a big no-no for video, but I’m not surprised, as Metabones does not recommend their ‘advanced mode’ for video either.

USB port and AF switch

For taking photo’s, both PDAF and CDAF work on the A7 III. On the original A7, PDAF does not seem to function. It shows the same behavior as the A7 III shows while in video mode, and can thus be considered unusable. PDAF on the A7 III works like a charm: face detection, snappy AF, even eye-AF! On the A7 III, PDAF works a lot better than CDAF. I would say that, depending on the lens, for photo, PDAF on the A7 III is on par with native lenses!
CDAF, which works on both the A7 and A7 III, feels a lot like a crippled variant of AF. Focus hunts in dimly lit scenarios, but eventually catches on. In better lit circumstances however, CDAF can achieve focus just as quickly as PDAF can. I would say that CDAF in photo mode behaves a lot like CDAF in video mode.

For both AF modes on the A7 III, all focus modes (AF-A, AF-S and AF-C) are available.

However, not all is good and well with this mount adapter. After using this adapter for a good few months, I noticed that this adapter sometimes causes the camera to lock up. For some reason, in some cases, it is unable to take a picture when I press the shutter button. The viewfinder freezes, and the camera becomes unresponsive. This can be solved by restarting the camera (sometimes the battery needs to come out, or the lens needs to be taken off and on again), so it’s not a big deal. However, if timing becomes a challenge in your photography, you cannot be a 100% guaranteed that the camera will actually take the picture, with this adapter! It’s hard to put an exact number on how many times this occurs. I recently took a trip where we went to a park, and I took maybe 100 photos with this adapter, with this flaw occurring maybe three times? I was taking all photos with Silent Shutter turned on, maybe that’s related to this issue? I’m not sure, I should do some more testing. It has however, never caused the camera to freeze during video recording, so if that’s what you’re into, you’re good to go!

One final remark is the noise that AF-C can introduce, on non-STM Canon lenses. Whilst filming, using the adapter in CDAF mode, and the camera set to AF-C, you can definitely hear the focus motor trying to keep focus. I’ve tested a number of lenses, including cheap EF-S lenses and more expensive Canon L USM lenses. All of these produce, to a certain degree, an annoying and definitely distracting, noise. The only exception to this is the only STM lens I have tested, the Canon EF-S 10-18 IS STM. This lenses is just as quiet as a native Sony lens, and can thus be used for video with AF-C.



  • Cheaper than both the Sigma MC-11 and Metabones adapters
  • Firmware can be upgraded
  • Contrast AF 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)

So, in conclusion, I’m very happy with this adapter, which allows me to use and experiment with various EF and EF-S lenses. So far though, after testing a number of lenses, including an EF-S 10-18 IS STM, EF 17-40mm F4, EF 17-35mm F2.8, EF-S 17-55 F2.8, EF 24-105mm F4 I, EF 28-105mm, EF 50mm F1.8 II, EF-S 18-55mm IS, EF-S 55-250mm IS, as well as the Tokina 11-16 F2.8, I’ve concluded that only lenses with an STM motor are usable for me, as I shoot mostly video with AF-C engaged.


14 thoughts on “Viltrox EF-NEX IV adapter (v1.8)

    1. Unfortunately, I sold my A7 mark 1, and I don’t have the opportunity to shoot with the 24-105 in the coming weeks. However, I did purchase a Canon 17-40 F4 L USM, and I will be sharing my experiences with the Viltrox and the new firmware once I return from my holiday. Then, maybe I can test out the 24-105, depending on whether my friend brings his along!


  1. I’m on firmware 1.9. My Canon 17-40 doesn’t make noises. Also, would you know what Test-v041 brings to the table? Thanks


    1. I should really update this post once I get back from vacation. The 17-40 I just bought hardly makes any noise during focusing, its a lot more usable than I initially expected! The “test” firmware, which I have loaded onto my adapter currently, should improve AF, but I’m not exactly sure what it does. I believe it said something about hybrid AF, combining PD and CD? I expect to be using the new firmware quite a lot in upcoming weeks, so I’ll update this post with my findings!


    1. I can test the performance of the 55-250 non-STM, as I know someone who can borrow me his copy, but I don’t have access to the STM version. Check back next week I should have written it up by then!


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