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

Mark Chan wrote:


answer simply. Have you had experience comparing the two lens - 17mm f1.8 and 20mm F1.7?

Which one is faster to focus?

Which one does focuses similarly fast under ALL conditions? Not conditions YOU stipulate in YOUR controlled test?

Can't answer that? Or will you still extrapolate from your findings?

Where in this thread have I said anything specifically about the 17/1.8? I responded to the OP's general claim about the 20 versus "other lenses".

Now two months ago I asked you the following here:

"Are you claiming that the 17/1.8 is noticeably faster than other modern lenses with similar AF design like the 12/2 and the 45/1.8 included in my test? If so, on what basis do you make that claim?"

You didn't respond. I have asked the same question of others as well and I have yet to see a positive response along with the evidence required to back it up. Obviously, the question presumes fully comparable conditions (same AF target, same magnification, same light conditions etc.).

The OP here had the 17mm f1.8; his statement comes from HIS direct experience using both lens, and stating he feels misled that the 20mm f1.7 would be fast enough.

According to his gear list he had it but no longer has it. Like you, he has apparently failed to test anything and is just reporting his subjective feelings.

YOUR picture shows a general condition that any point and shoot can take.

Exactly. So I proved you doubly wrong as already explained. The scene for which you said you needed fast AF (bikers passing by) doesn't really require it. But if you insist on AF-ing at the last moment rather than prefocus (as you should), the 20 will nevertheless do the job.

By way of summary: In spite of repeated trials, you haven't been able to come up with a single credible example.

Your controlled tests help you identify 'conditions' in which this lovely lens of yours will focus 'comparably' with other lens.


Maybe Panasonic should hire you to promote their lens. Do remember to tell them to place a sticker on the box stating 'AF works as fast as similar lens under 'set' conditions. Or to 'not expect' fast AF when focusing from close range to infinity or vice versa.

You mean something like this: "Warning: Not appropriate for split-second switches between landscapes and kids running around in close quarters (less than 0.75 m)."

So far, the only one in need of such a sticker seems to be you and you are no longer in the market for the lens. So I don't really see any reason for Panasonic to bother with it.

Seriously and you still think you are not misinforming others as regards the strengths and weaknesses of this lens.

Absolutely. And in contrast to you, I can offer evidence rather than merely subjective feelings to back up what I am saying.

When you propagate untested subjective impressions as though they were facts and when you spread allegations about me that you can't back up, then you are not only misinforming but desinforming others. With respect to me personally, your allegations amount to pure slander.

You state you are a scientist.

I am.

If you so want to continue claiming what you claim, do go and buy or loan a 17mm f1.8 or even the 25mm f1.8 and redo all your tests. EVEN then state clearly under what specific conditions the 20mm f1.7 works equal to them, and what conditions do not.

See above.

Be holistic please.

If you knew what the word "holistic" actually means, there'd be no reason for you to ask.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
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