Interesting read by Thom Hogan

Started Feb 14, 2014 | Discussions thread
EinsteinsGhost Forum Pro • Posts: 11,977
Re: Interesting read by Thom Hogan

socode wrote:

spacemn wrote:

GaryW wrote:

spacemn wrote:

GaryW wrote:

Where does it say that the fast-hybrid AF works on,say, the Nex-6?

The point is, if Sony is only going to produce FE lenses going forward, it'd be nice to be able to use them effectively on existing cameras. Maybe that would be a problem with APS-C lenses too? If it requires a FW update for every new lens, that's a pain, and Sony is less likely to do that for older cameras. It's a weakness in the e-mount.

It is not plausible to think that FE lenses won't work with PDAF AF on APS-C bodies. My APS-C 35mm f/1.8 for instance works fine with PDAF with my A7.

I think it is a big part of Sony's strategy that FE lenses must be attractive on APS-C bodies as well.

APS-C lenses should be attractive on APS-C bodies, but yet Sony requires a FW update for PDAF to work. (I applied this FW update on my Nex-6 already.) They have a short list of lenses that were part of that update. Next week, they could come out with a lens -- either APS-C or FE -- and PDAF wouldn't be supported (probably).

For example both 35mm and 55mm FE lenses have a great FOV on APS-C bodies. The FE 70-200mm is great on APS-C as well. Only ultra wide and standard FE zooms are probably not a great idea on APS-C bodies, but here we are talking about 2-3 lenses.

To me that sounds like a paranoid assumption.

It was perfectly understandably when some lenses had to be firmware updated to support a brand new PDAF technology.

With all due respect it isn't at all. It points to some reasonably-foreseeable aspect of the lens protocol that was simply excluded or missed by original engineers working to a deadline and delivering the bare minimum.

I doubt that. Developments today were likely planned 2-3 years ago. In fact, if you look at the original E-mount kit lens, Sony called it: E 18-55 OSS. That tells me that Sony had sketched out the possibility of going with FE lenses.

As for FE 55, one of the demo video for a6000 used that lens. In fact, I would assume that every new or updated lens (at least over last couple of years) and on both mounts by Sony, might be ready for focal plane AF system.

Does anyone with a real understanding of this know exactly what needs to be added? Commands to move a stepper motor to a precise stop? Do the lenses need to return current step point rather than simply a distance?

A good clue to me comes from RX10. It is a CDAF camera but it uses SSM which is unusual as PDAF requires a quick linear movement, but does not work well for CDAF. To meet CDAF requirements, Sony has used a piezo electric motor (which Sony uses for in-body image stabilization). So, SSM drives the lens in either direction quickly, and the secondary motor acts as a brake. If I were to bet on it, this dual motor SSM design may be part of new lenses on both mounts, and those updated on A-mount.

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