bigs

thats is scary. Lucky it did not scrape the speed booster lens. I think the only way to make it work, it to file down that rear part of the lens, until it does not make contact with the adapter.

​interesting theory. I think the "shorting" issue may be quite valid. I found the most issues when changing between green and advanced modes on the adapter. To do so requires the adapter to be dismounted either at the lens, or the camera side of the adapter, then while depressing the button on the adapter, mount it back, all while leaving the camera set to it's on position. After the remount, frequently with the a7s the camera will malfunction, display black, or no f stop values, etc. The only way to resolve is to do a battery pull, and then the adapter seems to work correctly again.

What is strange though, is my other Metabones Speedbooster adapter has no such issues on the a7s, and I can mount and dismount the adapter without any issues.

I am having issues using my Canon 50mm f1.2L and Canon 300mm F4L IS USM using the mark iv (0.4 firmware) on the a7s. Strangely, when using the original Speed booster with the same lens combination, it works perfectly fine. Not sure why they made the software or hardware different considering the speedbooster version just has an optical reducer.

Hi just got myself a Metabones smart adapter iv with updated firmware 0.4, and it intermittently crashes the a7s when I use the Canon 50mm f1.2L. Also the Canon 300mm f4L IS USM does not even work correctly, and perceptually locked up the a7s when the silent shutter is used. I thought the 0.4 update was meant to fix this issue.

The 300mm f4L IS USM does not even allow proper aperture control when used on the Sony Nex 5r.

I also own a Metabones Speedbooster original version, and all the same lenses that had issues with smart adapter iv, have no issues what so ever and works perfectly.

It seems the newer software or processor in the smart adapter iv is not as compatible as the older metabones speedbooster.

Please Metabones, maybe you could make multiple firmwares, one for better compatibility with video cameras like FS7, and another for digital emount cameras like the NEX 5r or a7s.