Last weekend I got confirmation for something a suspected for a long time: my Metabones IV + Sony A7 combination throws the calibration of the lens out of the tolerance range. It became very obvious when using Zeiss ZE lenses.
Those lenses behaved like expected when using them on my 5D2 Camera, i.e. they had some extra travel past the infinity focus point before they come to a hard stop, to compensate for small expansions and contractions due to temperature changes. When I received the Sony A7 with the Metabones IV that extra travel was gone on the 21mm and 28mm lenses and reduced to less than a quarter of what it used to be on the 50mm and 100mm. The Sigma 70mm and Canon 135mm, that I also use on that camera, are AF lenses that don't have a hard stop when used in MF mode.
When I received the Sony A7II I initially used it exclusively with my only Sony E-mount lens, the Loxia 35/2, to make sure that the A7II is indeed the solution to an unusual flare problem that I experienced with the Loxia/A7 combination. This lens works normal on both Sonys, focusing on infinity with some extra travel possible before hitting the hard stop. I used most of my other lenses for the first time on the A7II last weekend and found this (all lenses focused at the infinity indicator or the hard stop):
On the 21/2.8 ZE infinite focus is impossible to achieve. At the hard stop the image is still out of focus from about 7 yards from the focal plane on. The area between the camera and 7 yards away is tack sharp. This lens has recently been serviced by Zeiss and should be the last one in my bag to have problems.
The 28/2 ZE shows similar results, with the oof area starting at about 8 yards and being not quite as blurred (my impression).
The 100/2 ZE is tack sharp at infinity and beyond ( I know, sounds funny; but you know what I mean) when turned to the hard stop, without extra travel left. Infinity focus is also possible with the EF 135/2.
Interesting is the EF 400/5.6. Focus on a point about a quarter mile away was not possible. It comes close, but continuing to turn the focus ring increases blur again. Staying at the closest-to-focus setting and exposing resulted in an image that is tack sharp behind the point focused on and completely oof up to and including that point.
From all this I conclude:
- Both cameras have slightly different flange distances but are within tolerances, as the problem free use of the E-Mount Loxia shows.
- The Metabones adapter is slightly too long. It barely stays within tolerances with the A7 but exceeds those with the A7II.
- With increased focal length the problem shifts from focus before the intended point to focus behind it.
Of course, not being an expert I cannot be sure about my conclusions being right or what action to take to correct this. I have ordered a Photodiox adapter, not the least because it is guaranteed allow infinity focus with any lens. A possible hint at the problem with the Metabones being a known issue?