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

Started Apr 28, 2014 | Discussions thread
micksh6 Senior Member • Posts: 2,613
Re: I feel misled: Panasonic 20mm f1.7 II AF is SO SLOW!

Anders W wrote:

micksh6 wrote:

Why do you feel mislead? Of course it's slow and it has been shown here long time ago. You just needed to look at the right tests:

A "controlled" test can also show that 20mm focuses much slower than other lenses and hunts more often too. It's not needed to refocus from close-up to infinity in order to see that. These tests show refocusing between about 5 and 7-8 feet.

Those tests are not controlled. They are biased in ways and for reasons spelled out in the thread to which you link. That's why they are not the right tests.

The "bias" reasons were spelled in regards to first test (more than a year old). This is why I linked to a second test (9 months old) with corrected conditions, so all that bias stuff is no longer relevant.

When you reviewed the second test you couldn't come up with any bias arguments, only with minor nitpicking about viewing angle. These nitpickings were pointless because anticipating these I did several tests with slightly different angles and they all showed the same results. Here is your last post in that discussion: http://www.dpreview.com/forums/post/52056626

The test is as right as it could have been. Any more "controlled" test would also be less relevant because it would have to use artificial conditions, having nothing to do with real shooting.

Your test is a good example of irrelevant test because now you always have to add disclaimers like "when refocusing between 0.75m and infinity". Why didn't you test a real life scenario - refocusing between approximately 5 and 7 feet, like I did?

Your ending word was basically that "If you want to make one lens look like it would be more prone to hunting than other lenses, it's very easy to arrange that by means of any of a large number of seemingly minor side conditions".

It could be so, and that's where statistics comes to play. More and more people find that 20mm is slow comparing to other lenses. Nobody appears and says that 20mm is faster than recent primes such as 17mm F1.8 (especially that 17mm), both 25mm, 45mm F1.8. Isn't that telling something?

The best what people can say about 20mm AF speed is "it's fast enough for me" or "about as fast as some other lenses I own". And this also should have raised "where's your evidence" questions that you ask everyone who claims that the lens is slow, if you weren't so attached to this lens, of course.

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