Which Lenses work well with the FX9’s Autofocus?

advertise-here-275 Which Lenses work well with the FX9's Autofocus?

Below is a list of lenses that have been tested with the FX9’s advanced autofocus system. Generally any Sony E-mount lens will work just fine. The Sony G series lenses are good and the G Master series tend to be even better. 
For third party lenses and adapters the situation is much less clear, so I have decided to list the lenses I have tested and invite others to contribute to this list via the comments area. The list is not exhaustive at this time but I will try to keep adding to it as I am able to try more lenses and and different adapter combinations.

Inclusion of a lens on this list is not a guarantee that it will or will not work, it is simply an indication of how it worked for me or anyone else that adds information about their own experiences. I welcome updates and any further information from any lens or adapter manufacturer.

If there is a lens you have tested on an FX9 please let me know via the comments how it worked so it can be added to the list.

KNOWN TO WORK WELL:

Sony E (super 35mm) FE (full frame) lenses, G and G-Master including Zeiss ZA series. G and G Master  tend to have the best AF performance.

Tamron 28-75 f2.8 Di III RXD E-mount.

KNOWN TO NOT PERFORM WELL:

Sigma 20mm f1.4 ART native E-mount (very slow AF, hunting, contrast only?).

Sigma 85mm f1.4 ART native E-mount (very slow AF, a lot of hunting).

Sigma 20mm f1.4 ART Canon EF mount on metabones, comlite or viltrox adapters. Very slow AF, not really useable (MC11 not tested yet).

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4 thoughts on “Which Lenses work well with the FX9’s Autofocus?”

  1. Thank you Alister for your efforts. I appreciate it very much! We have the Tamron 28-74 Lens with our A7III and with this camera (and also with the FS7) it works well. So we might keep it, when we‘ll change over to the FX9.

  2. Great info as always Alister, thank-you.

    What holds back other lenses from working well such as the Sigma Art E-Mount series? Do you think Sigma will be able to upgrade the firmware in the lenses?

    Also metabones EF adapters? We’ve all got cupboards of EF lenses, to have to go out and buy a set it Sony GM lenses adds a hell of a lot of cost to the FX9!

    Looking forward to be able to do dolly moves towards subjects etc at low f-stops which is not possible really without a focus puller…well not for me anyway!

    1. I think part of the issue may be that because this is a hybrid phase based system the camera needs to know the precise distance the lens is focussed to.

      With most conventional types of contrast based AF the camera tells the lens to move, the camera checks the focus, is it better or worse?. If worse go the other way, if better keep going. This continues until the camera is happy that the image is sharp. This is why contrast based is often slow and often hunts because it based on several changes of lens position until the best sharpness is achieved.

      But phase based is different. The camera is able to calculate the amount the focus distance needs to be changed to achieve the best focus and will tell the lens to move to focus position “x” in a single move. Then the focus is checked. If it isn’t right the FX9 appears to then revert to contrast based and tells the lens to move in or out a bit, checks the focus and so on this it will then start to hunt.

      So for the phase based element to work correctly the camera has to know by exactly how much to turn the lens or tells the lens to focus at a specific distance. With Sony lenses Sony will know exactly what amounts or what digital values that will be. With 3rd party lenses, especially going through adapters that have to translate the protocols that information will not be there, so the system falls back to contrast only and what you get is no better than the FS7.

      While I’m sure we would all like to be able to use all that old Canon EF glass etc. a lot of older EF lenses were never designed for phase based AF, so they will never work well with the FX9.

      1. Thanks Alister, very helpful info. So based on that the Sigma Art E Mount line won’t ever be up to snuff it seems for autofocus, it’s a pity.

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