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Sony A7-Metabones IV - Canon 300mm F4.0 L IS


I got the Metabones IV adapter so I could use my Canon TSE lens on my A7R. At the time I discovered that it would work with most of my Canon lenses but not the 300 F4.

I now have the A7M2 while waiting for the A7RII.

The other day I went onto the Metabones site and discovered that there was a firmware update. (V0.41) for the adapter. I downloaded it and updated the adapter. It was a straight forward procedure.

I got out the 300 and give it a try. It worked. I can change aperture and I can hear the IS working when the shutter is half pressed. AF is still snail slow but that's OK.

This morning I tried the 300 along with two Sigma TCs. They work as well. Aperture control passes through. IS functions.

The test was shot at 16000 ISO, Av shutter, handheld. I was supporting the lens with my elbow on my desk. The poster is about 20 feet away. Sharpening is turned off in Lightroom.

The full frame and 100% crop for the 600mm version is included for reference.

I set OSS to manual and input the effective lens focal length via the camera menu.


New member
I think I must a a dud Metabones smart adapter iv. with my Canon 300mm f4L mounted on an A7s, it would periodically more often than less, just hang the camera, when the shutter was depressed. This does not occur when I use the older smart adapter version 1 or the first generation EF to Emount speedbooster on the a7s. Having the camera continuously crash and no capture exposures makes this combination totally useless.

Strangely, the 300mm f4L works a little better with the smart adapter iv combo on my nex 5r. ie slightly less crashing. I am debating just selling the Metabones smart adapter 4 in favor of a Kipon smart adapter.


The crashing is a frustration.
Its not as big a problem with my A7II as you're describing with the A7s. That suggests that its probably more than just an electrical contact problem.
Hopefully Metabones will work through the problem.
I think I'll send them an email and suggest that it needs work.