A7 + Metabones + Tough E-Mount = Bad

...at least in my case.

I thought something was wrong with my 21mm Zeiss, when OOF areas showed frequently near the corners. But then I also noticed that the infinity focus on my other manual lenses happened right at the hard stop of the focus ring travel, instead of a bit before, where it used to be.

Initially I blamed it on cold temperatures, which is known to change the focus point slightly and is the reason why the focus ring is designed to travel past the infinity point. But now that it's warmer again, it should be back to normal. But it isn't.

So I looked at something else that has changed, which is the e-mount. I had replaced the original metal/plastic mount with the all-metal "Tough E-Mount. Reversing that made my lenses behave normal again and eliminated the OOF areas on the 21mm.

Obviously the all-metal E-Mount is a tad thicker than it's supposed to be. I am thinking to have a machine shop take off a few mill, but have no idea how much. 3 mill? 5 mill?

It would be great if someone could give me a number that would be safe to use. Thanks in advance.

Well if you read their blurb it claims infinity focus is retained, so that would be a good case to have the mount replaced with one that maintained infinity focus.

Regarding how much needed to be removed, the only way to answer that would be to measure the thickness of the new mount and the original mount with a micrometer. Assuming they both seat the same way on the body then the approach would be remove any difference from the new mount. I think you would need to measure your mount in case there is some thickness variation in the tough e-mounts.

I would just use the OEM mount...though people jumped on the wagon to replace the mount, it seemed to work fine.

ChrisRoss wrote:Well if you read their blurb it claims infinity focus is retained, so that would be a good case to have the mount replaced with one that maintained infinity focus.

That's actually the tricky part. There are two components - Metabones adapter and Tough E-Mount - each by itself within acceptable tolerances, but combined too thick. Hard to tell which one is to blame. The E-Mount would be less trouble to correct, though, and also cheaper to replace if something goes wrong.


Then, Mike O's suggestion to use the OEM part has appeal. After all, the adapter is the one that's attached to the tripod, so all the mount has to hold is the weight of the camera; which isn't much. That shouldn't put much stress on the plastic of the OEM mount.

I'm guessing something isn't quite right with your tough E-mount installation. I've done a number of these conversions and no such problem has ever presented itself.

E.J. Peiker wrote:I'm guessing something isn't quite right with your tough E-mount installation.  I've done a number of these conversions and no such problem has ever presented itself.

My first thought was indeed that something went wrong with the installation. But there is only one orientation the mount can go on, determined by the position of the locking pin. Theoretically it's actually more error proof to install the one-component Tough E-Mount then the two-component OEM mount, and the latter doesn't cause any problem.

I am pretty sure the cause is the adapter/mount combination, with each by itself being within tolerances, but combined exceeding them.

Has any of the conversions you performed been used in combination with a Metabones adapter?

I just found that I am not the only one with this problem. I found this detailed review on the Amazon page that sells the mount:

>>>CAUTION: IF YOU USE MANUAL FOCUS LENSES WITH FIXED INFINITY FOCUS EITHER IN E-MOUNT OR VIA AN ADAPTER DO NOT BUY THIS PRODUCT!!!

I bought and installed this mount on my A7R camera. Installation was a breeze and this mount looks like a true quality product. But there is a major problem: it is thicker than the original and it increases flange-to-sensor distance making infinity focus impossible - UNLESS you use Sony or third-party lenses with floating infinity focus, in which case you may not notice any difference. The flange-to-sensor distance error is very significant - my Samyang 8mm Fish-Eye lens would not focus to infinity even with all the depth-of-field a Fish-Eye lens has. Fortunately, the fix was easy - Samyang used several spacers under the lens mount to calibrate the lens to E-mount infinity focus. Removing some of them solved the problem for this lens. In other instances I had to re-calibrate infinity focus on my lenses to compensate for the error. But in some cases, I had to either machine or replace adapters. But infinity focus error is not the only problem - some lenses and adapters would no longer mount on my camera, because their mount locking tabs became too thick to lock into this mount, requiring to machine the mount locking tabs. While I did not mind doing this to some cheap adapters, I did not want to machine lens mounts.
OK, I have the tools, the know-how, sufficient time and just enough insanity to mess with all of this, but what about the majority of normal folks out there?
I think, it is fairly easy for any lathe or milling machine operator to properly measure the thickness of the original part and then machine to the same exact tolerances. I do not know who in China manufactures these mounts for Fotodioxx, but they need to re-check the specs they've provided to the manufacturer (if they did) and if those were correct they should change their supplier immediately.
I would have requested a replacement, but since I realize that all these mounts are identical, there is no point. Since it is too late for a refund, I will eventually measure and machine this mount into specs and I hope Fotodioxx will take my advice.<<<

There are five more reviews on that page that mention the same problem, one specifically reporting problems with the Metabones IV. I will try to return the mount for a replacement (I've had it for quite some time).