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!

micksh6 wrote:

Anders W wrote:

micksh6 wrote:

NZ Scott wrote:

s_grins wrote:

Mark Chan wrote:

You know, I made the view that the PANA 20mm f1.7 was slow to AF and should be avoided by those that need to take pics of kids and fast moving items / people. This was quite a few threads back.

There are a few that adamantly state my (and many other's experience) is flawed and that the PAN 20mm - both versions are perfectly capable of 'catching' that moment.

Its plain not.

Choose 17mm or 25mm OLY for that.

Choose 20mm f1.7 if you don't NEED fast AF under any circumstances or are perfectly happy to live within its limitations.

It is unfortunate you got misinformed. And yes there are many that are misinforming leading to poor purchase decision.

I do not have photos of kids (I do not have grandchildren, yet), but I have one old photo of the dog. As you know, dogs even more difficult in compare with children.

I think this is a poor example. The dog is stationary - not exactly running towards the camera or anything like that.

We don't know, maybe the dog pushes the table towards photographer and does it really fast.

20mm lens owners probably didn't try photographing at bowling places or anywhere with the light level about ISO1600, F2.0, 1/20s. I did, and 20mm lens is barely usable in such situations.

I don't know about you, but I certainly have no difficulties getting my 20 to lock on a target like that at the light level you mention. But are you saying that this is a scenario where AF, let alone quick AF, is at all needed?

For shooting a scene like that, I'd already have set focus in advance so that I can capture the right moment.

Except that you won't know where the "right" moment will happen. Young kids are unpredictable, they can throw ball at any point. The boy on the picture sometimes does it few feet earlier than on that photo, but sometimes after the lane starts.

That's precisely why you shouldn't wait to AF until the boy takes action. If you do the AF at the last moment, you'll have a shutter lag of several hundred milliseconds. If you have pre-AFd or MFd, that's down to about 50 milliseconds, giving you much better prospects of catching the right moment.

And the only landmark to prefocus here is the floor that lacks high-contrast details, plus it's not parallel to camera. Such AF target is exactly what makes troubles with 20mm lens.

It doesn't have to be parallel to the camera. And I see some text at the beginning of the lane that would certainly work as an AF target if the floor wouldn't suffice (as I think it would). If nothing else helps, just ask the kid to stand somewhere along his throwing path, or move back to where he stands, get focus, and return to the proper point of capture. Or just MF on something at the same distance.

Yes, I know the tricks to deal with slow-focusing lens, had to learn them during 2 years of owning 20mm F1.7. Using such tricks is what takes fun out of photography and makes it rather a job.
I'd rather choose a lens that doesn't force me to do tricks, such as 17mm F1.8.

To me, pre-focusing whenever that is possible and no matter which lens I am using, is not even something I have to think of, let alone something that takes the joy out of photography. On the contrary, it gives me more fun by letting me concentrate on what is really important in order to get my images the way I want them.

17mm F1.8 lens, however, locks focus without problems. Here is an example



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