Focus on GH4

[RyanKhoo]

Hi there,

I am not sure how you guys solve this but I am getting quite irritated with this.

You see, I used the GH4 to record videos. I am on auto focus. The subject also do not move much.

When I record, I touch on the LCD screen to indicate where I want the focus to be. It looked fine and good.

But when I come home, download it and play back on the desktop iMac, sometimes the video are blur (ie out of focus) ... why is the LCD screen not accurate ?

How do you solve this problem ?

Thanks

 

[Deunamist]

focus manually.. because AF makes your focus jump in and out.

 

[kandinsky]

You see, I used the GH4 to record videos. I am on auto focus. The subject also do not move much.

When I record, I touch on the LCD screen to indicate where I want the focus to be. It looked fine and good.

That only tells you it was sharp at the point you set the touch AF, it doesn't guarantee anything after that. You have to keep monitoring the LCD throughout to see if the focus is tracking, since your subject is still moving (even if not much), and reacquire focus (e.g., touch AF again) if the AF has lost focus...

Share a sample clip?

 

[RyanKhoo]

focus manually.. because AF makes your focus jump in and out.

Yeah I supposed so. Now I know why all the pros use manual focus ...

You just use the focus peaking (blue color) to judge, right ?

That being the case, what then is the purpose of AF when the focus jumps in and out ?

Thanks

 

[RyanKhoo]

That only tells you it was sharp at the point you set the touch AF, it doesn't guarantee anything after that. You have to keep monitoring the LCD throughout to see if the focus is tracking, since your subject is still moving (even if not much), and reacquire focus (e.g., touch AF again) if the AF has lost focus...

Thanks kandinsky.

Btw, have you come across the case when you look at the LCD you think it is focus but then when you download it, it is not 100% focus as you would like it to be ?

Could it be bcos our LCD screen is so small where as our monitor screen is huge ?

Share a sample clip?

Aiyah ... I should have kept it to show you ... but I deleted it bcos it was blur and cannot be used ... :mad2:

 

[Deunamist]

Yeah I supposed so. Now I know why all the pros use manual focus ...

You just use the focus peaking (blue color) to judge, right ?

That being the case, what then is the purpose of AF when the focus jumps in and out ?

Thanks

Hahaha.. whenever possible I use peaking la.. but when I use my GH3, no peaking, gotta use a monitor (for critical work) or trust my eyesight (for non-critical work)

 

[kandinsky]

Thanks kandinsky.

Btw, have you come across the case when you look at the LCD you think it is focus but then when you download it, it is not 100% focus as you would like it to be ?

If it's sharp on the GH3 LCD/EVF, it's sharp on the desktop. It might happen if I'm wearing my older glasses (which are slightly underpowered).

Could it be bcos our LCD screen is so small where as our monitor screen is huge ?

Yah, I think small screens tend to look crisper. Possible for it to give you the impression that it was sharp, especially if your eyesight is not perfect. While someone else with good eyesight might have seen the same thing on the LCD and noticed that the AF was slightly off? Some people get an external hdmi monitor for this reason.

Aiyah ... I should have kept it to show you ... but I deleted it bcos it was blur and cannot be used ... :mad2:

Lol, next time keep the mistakes, esp if you want to ask questions about it. I'm sure we can all learn something from it.

That being the case, what then is the purpose of AF when the focus jumps in and out ?

Then you might as well ask what's the purpose of Auto WB when the white balance shifts in and out? Anything 'Auto' will have its limits. Are you shooting 4K? I've read that the AF in 4K video mode is slower than HD in the GH4, probably due to the amount of data the processor has to deal with?

http://www.43rumors.com/small-surpr...k-recording-mode-while-its-damn-fast-at-1080/

 

[Bamboopictures]

Shame the GH4 has no face detect like the C100 mk2
[video=vimeo;115789683]https://vimeo.com/115789683[/video]

 

[Bamboopictures]

or does it?
[video=youtube;uwT1c6CMI3c]https://www.youtube.com/watch?v=uwT1c6CMI3c[/video]

 

[hamanoshun]

Manual focus all the time. ALL THE TIME, especially if it's video.

And small lcd screen, too small to discern what's in and out focus. Get a on-cam monitor if you have to.

 

[XsenseX]

Confirm will have focus breathing if you are Autofocus ...

So far, the best combination for autofocus is if i use the 12-35 (at 12mm) and >f5.6 and also importantly, the subjects are >4metres in front of the camera.

Basically that means everything is in focus.

I use it frequently while on the glidecam cause we can't focus while tracking. I could just set it to 'near infinity' manual BUT the autofocus did save me a few times when the subject suddenly walks too fast and become 1-2metre in front of me.
In those situation, as long as you keep the subject right in the middle and most of the 'screen real estate' is covered by him/her then the autofocus won't produce focus breathing.

Once i've zoomed in, i switch back to manual focus. No way to use autofocus for tele modes.