Zooming slowly prevents jumping/hunting for focus

G

Gugulino

Active member
With the Lumix 14-140 HD lens on the AF100 I often saw some jumping of the auto-focus when I zoomed or panned. I found out when I do it slowly the auto-focus gets very precise: Zoom in and after zooming the auto-focus finds very quick and accurate the new focus. Without jumping around!
I tested it in 720p50 PH mode. And it seems really that the auto-focus is only jumping around when you do quick movements with the camera. Can anyone confirm this and has anyone an explanation for this?
I think when you zoom in fast the camera gets lost, does not anymore where the focus is. When you zoom slowly the camera can track focus and after zooming it can set the new focus very precisely and fast.
Does the camera adjust the focus during zooming or only after zooming? I see on the display that the focus distance is only adjusted after zooming. But, this may be only caused by the software, which can not display the zooming numbers and the focus numbers at the same time. That would also explain why the camera can find such rapidly the right focus after zooming slowly. It can adjust the focus steadily during zooming, but it displays the number only after zooming.
What do you think? Is my conclusion correct?
 
In my experience all autofocus systems have their weak spots..
With a crash zoom or whip pan i found the Lumix lens to be pretty fast in autofocus it may hunt around a bit but then it settles as opposed to Sony's which dont hunt but take longer to get there.

The autofocus system in any camera does need something to "bite" on to before it can make a decision, pan or zoom fast enough and they all lose focus.
i put a video up with the AF101 fully auto
Its the stepping of the Iris I would love to see Improved..
 
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Sure I should have posted the link...

here

you can see the Iris change is those discrete steps, the long pan up the barge starting with the stern ...full autofocus
 
Vultch said:
Sure I should have posted the link... you can see the Iris change is those discrete steps, the long pan up the barge starting with the stern ...full autofocus
Click to expand...

I agree that the auto-focus works well but I would definitely take the iris off 'auto' setting and go manual all the way. The iris changes makes the scene unusable for a pro application.
 
Did you use the LUMIX 14-140 lens? It is crazy how fast you can follow the bucket and it does not lose focus. Perhaps, because the auto-focus has something to follow. But, the iris changes are clearly visible, also in my experience. Yesterday, I filmed a concert of a choir in a church. I had the iris to manual and fully open, because it was rather dark. When I zoomed, the auto-focus got lost and jumped around. Sometimes even when only the light changed the auto-focus began to jump around. I think the lightning conditions were not ideal.
But, in your video I can not see any zoom scene? In yesterday's event I had to record the whole event at once. So, I could not zoom set the focus and then press record. All was recorded: The focus jumping around, the manual and uneven zooming. The zoom ring of my 14-140 LUMIX lens gets harder to turn the more tele the lens is. But, it is only a small range, after that it gets again smoother. Is this normal?
 
I agree with spyke, focus looks great but set your f-stop and leave it off auto. Nice stuff by the way.
I attended Barry Green's af100 seminar last weekend, we put the Lumix 14-140 along side some very expensive cinema lenses, optically not much difference to my novice eye.
 
Thanks Guys, that footage was a test ( I had just taken delivery of the camera) it was about me getting to know the camera hence i wanted to see what it was like in full auto. And yes it was using the 14-140mmm lens.

I now shoot fixed iris/exposure ...it would be good if the steppy behaviour of the lens could be addressed

All autofocus systems have difficulty in low light, my old "work issue"Sony Z1 was just as bad.
And Yes I like the lumix lens.. ok sort out the steppy auto iris and it does ramp a bait... but the image it produces is quite pristine... never had a set of expensive primes thou so i cant compare...

I use a Manfrotto focus/Iris controller... great kit and i modified my mechanical follow focus system to now control zoom... its a personal thing..
 
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