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NEX - AF for Alpha Lenses

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tigertimb

Guest
Nearly every one of the original Minolta lenses are screw driven with the motors in the body of the camera. And the better cameras normally have the better motors and so giving the possibility to focus faster.

This was continued for a while by Sony and whilst all the Alpha bodies still have the motors, more recent lenses have in-lens motors.
(N.B. the Zeiss 135mm and 85mm were still screw driven, so two of the current signature lenses for the system need the in-body motors)

With the in-lens motors, SSM is the better and more expensive option for the more expensive lenses, and SAM is it's cheaper cousin.

The adaptor for the NEX does not have a motor in it, and I saw arguments to say that within the thickness of the adaptor there wasn't the space to feasibly fit a motor to drive the screw lenses. (we can still hope though and maybe some enterprising 3rd party will produce one, now that the firmware makes the option useful)

So the only lenses in the current Sony line up that will autofocus with the new firmware will have the SAM or SSM designation, and roweraay listed those you're likely to consider above.
 

douglasf13

New member
If the AF of Alpha lenses on NEX is anything like what I've read about the AF of 4/3 lenses on m4/3, I'm not really that excited by the possibility.
 
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tigertimb

Guest
Maybe true, but what happened to 'innocent before proven guilty' -;)
You've got to at least hope that the reason that Sony took so long is because they were getting it right, particularly as pre-production cameras were supposedly already working.

Remains to be seen if it will work with Sigmas and Tamrons too, but if so, I think the Tamron 60mm f2 macro might make my wish list
 

Mark K

New member
All I know from so called insider is that the AF process drains battery too quickly that they think. Besides, there is a design problem for upcoming Zeiss lenses with E mount. The bulk will be too much if SSM is built inside the lens.
 
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GaryW

Guest
The 28/2.8 is a lousy performer overall and since it does not have a built-in motor, it will not AF with the upcoming change. ...
A lot of people complain about the 28/2.8 (and less so the 50/1.7), but one of the sites showed the sharpness to be better than most zooms. I thinkthe catch is it's worse than all of the primes! Oh well. I'm not sure I would call it lousy. It took fine pics.

I found mine to be sharp enough- the same or moreso than my other lenses at that focal length. When I was shopping for lenses, it was the cheapest a-mount prime.

MF is going to be an issue.

Also, some of the older (film) lenses seem to be more prone to flare or blooming (pf) or something. I can often see a difference. But sharpness and bokeh may end up looking better.... Or not. The kit lens bokeh is pretty nice.

My thing is, unless I see a substantial quality difference over the kit lens, I might as well stick with that. I haven't had the time to do a lot of comparisons.

So, for now, I'm not sure I'd recommend the 28/2.8, only because I think the kit lens is probably good enough, but I'd like to compare sometime.
 

gsking

New member
All I know from so called insider is that the AF process drains battery too quickly that they think. Besides, there is a design problem for upcoming Zeiss lenses with E mount. The bulk will be too much if SSM is built inside the lens.
People made this same comment about SSM lenses vs regular screw mount. I'm not sure it was ever proven. Perhaps the silent movement made people AF more than they realized?

In any case, I would think that focusing mode or method is less important than lens mass. Assuming all efficiencies are similar, the only thing that would matter is how much glass is moved. A large telephoto will take more energy to focus than a small prime, regardless of focusing motor or adapter configuration.
 

barjohn

New member
One can see that on the NEX the lens is constantly pre-focusing so that AF performance will be fast, undoubtedly that consumes more power but I think it is a good trade off and better than slow AF.
 
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