AF-D Support and 3rd party lenses on A99

[mikeyp2000]

Hi Sony,

Thanks for today's SLT-A99v firmware update. I am very happy my Sony Zeiss 85mm lens is now supported in AF-D mode.

I have two questions about AF-D and third party lenses.

1) Are there any plans for support for lenses made by other manufacturers? In particular, I own a Sigma 70-200/2.8 EX DG Macro HSM mkII and it would be fabulous if my A99 could work in AF-D mode with this lens.

2) I own a Tamron 90mm macro lens that now works in AF-D mode. This is because it shares the Lens ID with the newly supported Sony 100mm Macro lens. Is there anything I should be aware of when trying AF-D mode on a lens that is confusing the camera this way? Are there any deep technical documents explaining more how AF-D works so I can understand what is going on? Can I expect AF-D to work reliably with my Tamron 90mm. If not why not?

Sorry that question 2 is made up of many smaller questions. As you may gather, it is hard for me to understand exactly what AF-D mode is doing differently to AF-C mode and the internet/google isn't providing much more information!

Thanks, Michael

[Si_1966]

Hi Mike,

Two very value and well put questions. Given that Sony's latest firmware update is about lenses and AF-D support I hope they openly respond to your questions. Personally I am pleased with the updates as it covers my entire lens range now but I thinking of getting a number of third party lenses that would benefit from AF-D for sure.

I second the request for more detail Sony.

Si

[cmosse]

HI

There is one patent online describing PDOS technology.

http://www.google.com/patents?id=qJvIAAAAEBAJ&zoom=4&dq=inassignee%3ASony&as_drrb_ap=b&as_minm_ap=1&...

PDOS requires knowledge of some key lens data like size and location of the exit pupil. Therefore lens data has to be known to the camera and I assume this is the reason why 3rd party lenses get no support for this AF-D mode.

Michael

Message was edited by: cmosse

[mikeyp2000]

I tested my Tamron 90 in AF-D mode and it was able to track reliably and accurately even when the object being focused on was way outside the standard 19 AF points and only covered by the lower few AF assist points.   I was suitably impressed!  (I don't normally think of my macro lens as a star performer at tracking focus!)

So I wonder how much measurement effort is actually involved.  Adding support for some popular 3rd party lenses would certainly be a good thing for users.

However, I'm sure Sony really would rather I paid for a 70-400G or outdated 70-200G...

[cmosse]

I think the following happens:

The Tamron 90mm shares its lens ID with the Sony 100 Macro lens. Both lenses, beinig macro lenses with the same aperture size, may share some basic optical similarities which therefore make AF-D mode to work even if the lens is not supported offically (camera does not know specific lens data as it does for the Sony 100mm lens).