I feel misled: Panasonic 20mm f1.7 II AF is SO SLOW!

Started Apr 28, 2014 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: Well duuh, Panasonic 20mm f1.7 II AF is SLOW

Wesley Byrne wrote:

Ulfric M Douglas wrote:

Wesley Byrne wrote:

... I had read the reviews and knew the Panasonic 20mm f1.7 autofocus wasn't fast, ... This lens is useless for even slow moving subjects. ...

There you have it, you misunderstood.

It is not a lens for subjects moving towards or away from the photographer.

Rant about your own comprehension skills?

The Lumix 20mm is sharp, with a bright aperture and a tiny size.

Three out of four ain't bad.

Buy the Sigma 19mm or Olympus 17F1.8, or either of the 25mm.

And yet some claim that the 20mms f1.7 AF is not so slow, in this very thread.

At least one of them didn't just claim it. He showed, by means of controlled testing, that it isn't so slow (about on a par with other lenses) under the specific conditions he outlined (AF-S, focus range of 0.75 m to infinity, no hunting). See here:


Other tests have shown roughly the same thing, for example this one


Additionally, the following properties of the AF of the 20/1.7 are are well established:

1. It is unusually slow when it hunts.

2. It is unusually slow when it moves across the entire focus range (as opposed to the range from 0.75 m to infinity).

3. It doesn't work or works poorly in AF-C.

4. It works poorly if you want to AF during a video clip (e.g., because it is not completely silent).

I understood that some reviewers said the AF was a little slow, and that some reviewers said that it was plenty fast. I took a chance on the lens because it is small, bright, reported to be sharp, but was misled by comments stating that the AF is fast enough for general use (understood not to include action shots). It isn't a big deal, really (I can return the lens), but I do feel misled.

There are lots and lots of threads about the AF behavior of the 20/1.7 before this one, some of them discussing the matter in considerable technical detail. While you are of course free to say that I and others have misled you by reporting test results like those I linked above, I would personally not make such claims without having more in the way of evidence to offer than you do (i.e., none whatsoever this far).

If your subjective impressions are significantly out of line with the objective evidence provided by me and others, the likely reasons are a) that your copy of the lens is defect, b) that your perceptions are in error and/or c) that you have not compared the lenses at your disposal in an unbiased and controlled manner.

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