"deliberate touch" and the E-M1's touch-screen technology
William Porter wrote:
First, let's address your claim that "long touch" makes a difference. I am absolutely willing to be proved wrong, but as far as I know, "long touch" is NOT a gesture supported by the E-M1's touch screen. I've searched for any mention of it in the user manual and can't find it, and I've never read anything anywhere else that mentions long touch. Your video doesn't demonstrate that long touch works. It just demonstrates that some touches work and some don't.
Hi Will, all I can say is that you should try it yourself on your EM1, set the target box to the smallest size with Full Time AF to off, and test it.
Well, well. I think I see what you mean!
I've played with it a good bit more now. Okay, I've spent a ridiculous amount of time tapping on and touching the back of the camera. Anyway, I now understand what you were thinking of when you started the thread with the word "craziness".
Once again, for sake of clarity (and for the benefit of those who are joining this thread in the middle), my settings:
- Full-time AF "off" (MENU > Gear > A)
- Focus mode set to AF-S
- Touch screen focusing set to your #2 (touch moves target but doesn't take photo)
I know video matters to you but I'm talking here only about shooting stills. Doesn't matter but let's say I'm in A mode with lens stopped down a bit so that shifts in focus from near to far are more visible.
So what do I see now after all this tapping and touching on the E-M1's monitor?
First, I see now that a tap sometimes does NOT cause focus to move, even when the object tapped on has good contrast.
And second, I see that a slow, deliberate touch will usually force the focus to change, when a previous quick tap failed to do so. This is what you called "long touch."
And I think I have an idea what's going on here. The touch screen system is getting confused. Even if it's been responding to quick taps pretty well, I can confuse it in two ways.
The first way to confuse the system is important because it's easily reproducible. If I tap on a near object and then very quickly tap on a far object — requiring autofocus to respond to the second tap before it had finished responding to the first tap — then it will get "confused" and the result will be a focus somewhere in the middle. I can make this happen pretty close to 10 times out of 10.
The other way to confuse the autofocus system (with the settings described above) is not so easy to reproduce, but seems simply to involve a "bad tap." Sometimes I'm tapping away, refocusing nicely after each quick tap, and then I tap badly — and the autofocus system starts messing up. I can't do a bad tap on purpose, but I've observed the effects of it. I think you made a "bad tap" in your video at 2:14.
Note that when the system gets confused, it is still responding — it's just not responding well.
What to do when the AF system gets confused?
The main remedy is to use a "slow, deliberate touch". 99% of the time, autofocus will respond as you wish. You illustrate this in your video just after 2:35.
Beyond using the slow deliberate touch, `I haven't figured out how to get the camera responding once again to quick taps. I've tried turning the camera off and back on, and that doesn't seem to reset the autofocus reliably. Sometimes touching the magnifying glass icon on the screen (lower right, under the focus area size adjustment slider) seems to help. And sometimes, while I'm tapping away on the screen, it seems to fix itself. That to me looks suspiciously like a firmware bug.
The "bottom line" then seems to be that short taps work a lot of the time, but that deliberate touches are much more reliable. Which is good to know.
And by the way, touch AF for stills is not that important, video AF is more important.
I know you're interested in video, but as a portrait shooter, I rather like tap-to-focus on the E-M1. Works nicely when camera is on tripod. That's part of the reason I've been willing to struggle with this problem until we sorted it out. Thanks again for staying with me.