AF100 and LUMIX 14-140 f3.5 brand news lens could not focus

S

skmami

Member
I recently bought a brand new LUMIX 14-140 f3.5 lens and I mounted it on AF100 and used it in auto focus mode. Unfortunately it could not auto focus properly. Just wondering if this is a issue with the AF100 or the new lens. I really appreciate it, if you guys can shed some light on it.

You can see the video here : https://www.youtube.com/watch?v=LRDO7zR3Jmc

You can see several times it is going out of focus in the first one minute itself. Please see at marker 0:36 very it is highly visible.

Is there any setting in the AF100 that causes the auto focus to stutter. ?

Sorry about the weird angle I was shooting this video from.
 
You cannot rely on auto focus in this situation. The lens is confused on what to focus on. You should almost always use manual. If you find it hard to focus, use the red outline and if you still can't see enough to focus accurately, get an on camera LCD monitor like the Marshal.
 
At :36 you zoomed in. That lens is not parfocal. When you change the focal length, the focus changes. Then the lens has to re-hunt focus. This lens will not hold focus through a zoom.
 
Paul F said:
At :36 you zoomed in. That lens is not parfocal. When you change the focal length, the focus changes. Then the lens has to re-hunt focus. This lens will not hold focus through a zoom.
Click to expand...

Thanks Paul. Yes, at :36 I was zooming but I noticed the same behavior even when I was not zooming. You can notice that in the same video in other places. I got few other videos which I have not uploaded to youtube where I had this problem even when I was not zooming.

After I was done with the event I started looking into the AF100 menu options and I found one menu item under SW MODE --> FACE FRAMING which has three options to choose. It was set to PRIMARY. Other options were OFF, ALL.

Just wondering if this is what has caused auto focus to behave badly. ?

If this is the case then should I use OFF so it won't hunt for one person to focus on since I have many dancers on the floor who I want to equally focus.

Thanks
 
I don't have much auto-focus experience. I mostly use manual. The only time I've used auto focus is when I have a single person in the frame and I am walking around with them. It works ok in this situation.

For the shot you have, the focus doesn't need to change as long as you don't change focal length. In that case, put the lens in manual mode. If you are changing focal length, then you have a problem. You see what happens with auto. With manual, you will have the same problem. The only way to deal with it in manual mode would be to have a remote focus unit plugged in and have the focus marks preset for each focal length. Then when switching focal length, have a second operator switch focus marks simultaneously.

As grey said, you can't expect miracles. How was the lens to decide what to focus on with a bunch of dancers moving around. You can try the face tracking mode. But again, what happens when one face blocks the other in a dance routine. I don't know.
 
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