Is the Panny 20mm f/1.7 slow to focus on the GX7?

Started 9 months ago | Questions thread
Anders W
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Re: Is the Panny 20mm f/1.7 slow to focus on the GX7?
In reply to Ken Strain, 9 months ago

Ken Strain wrote:

Gunnlaugur Gudmundsson wrote:

Yes it is a new newer version, but the changes are only cosmetic (all black / all silver version also I think), the performance is supposed to be the same ...

and that means it is not obviously slower than other MFT lenses, when the speed is limited by the camera, as is the case for "normal" changes in subject/focus distance i.e. between objects more than 1m away. On the other hand it is slower than some other lenses when the limit is due to the focus motor, i.e. when there are pronounced changes in distance from close focus e.g. <0.5m to infinity. I suspect that this lens also "feels" slower than it actually is because the motor is clearly audible, at least that is my impression.

Note however that, according to the manual*, AFC and AFF focus modes don't work with the 20mm on the GX-7. (I've tried the lens but had not tried either of those modes.) That might be more significant than the slight speed differences (or not, depending on what you need).

*p46: "When the interchangeable lens (H-H020A) is used, [AFF] and [AFC] cannot be set."

Ken

Hi Ken,

Thanks for your "preemptive" action. It saves me the trouble of saying pretty much exactly what you already said.

Another way of putting it would be as follows: Yes, the AF of the 20 is slower than that of most other MFT lenses except when you shoot stills in AF-S, switch between focus distances in the range from about 0.75 m to infinity, and fail to send the lens hunting. For me, this "exception" accounts for more than 99 percent of my usage of the 20.

Some evidence with regard to AF behavior in this "exceptional" case here:

http://www.dpreview.com/forums/post/50877416

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