GH5 and focus issues with non-panasonic lenses?

I have 3 Olympus lenses and 1 Panasonic lens for my GH5. I use the cam primarily for filming.  The Olympus ones including the high quality f2.8 m zuiko lenses are almost gaurenteed to lose focus when zooming.  Example

Https://youtu.be/azkriMostH0

However my Panasonic 14-42 pz lens actually does an acceptable job as long as you are in good lighting.  Is it possible my camera and lens are not communicating properly?  I have yet to update the firmware on my camera but I browsed around and saw that you can update the firmware for both as some sort of combo?  Looks complicated too, apparently u have to load the firmware on an SD chip.  My Sony a6500 was a breeze to update.

Would really love some help.  At an airshow and #$@&ing tired of getting great footage and then COMPLETLY losing focus for a couple seconds

'when zooming'

Can you specify the lenses? Some lenses are designed in a way that focus doesn't change as they're zoomed (parfocal), others are not, and that's independent of the body which might or might not be able to compensate by quickly refocusing said lens.

MilitaryAttractions wrote:

I have 3 Olympus lenses and 1 Panasonic lens for my GH5. I use the cam primarily for filming. The Olympus ones including the high quality f2.8 m zuiko lenses are almost gaurenteed to lose focus when zooming. Example

Https://youtu.be/azkriMostH0

However my Panasonic 14-42 pz lens actually does an acceptable job as long as you are in good lighting. Is it possible my camera and lens are not communicating properly? I have yet to update the firmware on my camera but I browsed around and saw that you can update the firmware for both as some sort of combo? Looks complicated too, apparently u have to load the firmware on an SD chip. My Sony a6500 was a breeze to update.

Would really love some help. At an airshow and #$@&ing tired of getting great footage and then COMPLETLY losing focus for a couple seconds

Yes loosing the focus while zooming is "normal" (even mentioned in manual) and some tests confirm that the same issue is with EMk 1.2 as with GH5.

As Vlad said it is normal for focus to change when zooming. Some  lenses do it more than others but it doesn't matter in auto focus.

Michael1000 wrote:

It is my understanding that Panasonic GH5 has lens data stored in the camera for Panasonic lenses that tell the camera how much the focus needs to change to get in focus. So it first reads how out of focus it is, and then based on that data, it goes to the lens data table to see how much focus change it needs to get in focus. It is able to go straight to in focus, with only minor corrections. Also if you get new Panasonic lenses that don't have this lens data in the camera firmware, the GH5 will read the data it needs from firmware in the lens.

Olympus has not put this data in the firmware of their lenses for the GH5 to read. Therefore, the GH5 has to rely on trial and error using the contrast based focusing system to get in focus, which ends up in a number of overshoots until it zeros in on the focus. This is a much slower process.

That's DFD, which is something different. Yes it does focus at once (similar to PDAF) for faster focusing, but I think what the others are talking about are actually more correct. I don't believe the OP loses focus with the Panasonic lens and then reacquire quickly.  Rather the lens never changes focus through the zoom range.

The Panasonic PZ lenses appear to be electronically parfocal (on Panasonic bodies). This means as you zoom, the lens attempts to maintain focus at the same distance electronically. It's not truly parfocal given this doesn't appear to work on Olympus bodies.

Your sample to me indicates how a camera can lose focus, not just during panning and zooming, but by people crossing the scene. You are panning, zooming, and have lots of other subjects crossing the scene that confuse a camera on what it is you want to have in focus. There is no way you are going to be happy with any camera doing a scene like the one you post. I don't care what lens or what camera you have, you need to practice your filming technique to get more predictable results. Watch professional films to learn how pros do challenging scenes if you want to avoid what you are getting.

Michael1000 wrote:

JakeJY wrote:

Michael1000 wrote:

It is my understanding that Panasonic GH5 has lens data stored in the camera for Panasonic lenses that tell the camera how much the focus needs to change to get in focus. So it first reads how out of focus it is, and then based on that data, it goes to the lens data table to see how much focus change it needs to get in focus. It is able to go straight to in focus, with only minor corrections. Also if you get new Panasonic lenses that don't have this lens data in the camera firmware, the GH5 will read the data it needs from firmware in the lens.

Olympus has not put this data in the firmware of their lenses for the GH5 to read. Therefore, the GH5 has to rely on trial and error using the contrast based focusing system to get in focus, which ends up in a number of overshoots until it zeros in on the focus. This is a much slower process.

That's DFD, which is something different. Yes it does focus at once (similar to PDAF) for faster focusing, but I think what the others are talking about are actually more correct. I don't believe the OP loses focus with the Panasonic lens and then reacquire quickly. Rather the lens never changes focus through the zoom range.

The Panasonic PZ lenses appear to be electronically parfocal (on Panasonic bodies). This means as you zoom, the lens attempts to maintain focus at the same distance electronically. It's not truly parfocal given this doesn't appear to work on Olympus bodies.

That's interesting. I didn't know the Panasonic lenses did that. How are those lenses that have that feature identified (something in the model name)?

Also I wonder if they can also electronically compensate for focus breathing.

Unfortunately this does not appear to be identified in any systematic way. And given it is doesn't appear cross compatible between systems (Olympus vs Panasonic) that makes it even tougher.

For example, here's a thread that tries to find parfocal M43 lenses:

https://www.dpreview.com/forums/thread/4130430

You will note that the 45-175 is listed as not parfocal on a EM-5 II.

However, LensRentals says it is a parfocal lens for video:

https://www.lensrentals.com/rent/panasonic-pz-45-175mm-f4.0-5.6-ois

This test suggests it is (at least on a GH4 body):

https://www.youtube.com/watch?v=pHkbjD1VIfs

However this review says it's not on a G5 body:

https://www.amazon.com/review/R3CX35RED8A35X

I'm guessing given the inconsistencies (and perhaps effectiveness of it; I can see it varying depending on the zoom speed), it's not really advertised.

I forgot where I read it, but also, this electronic parfocal only appears to work well if you set focus zoomed in, before zooming out. Doing the other way around may be less accurate.

timccr wrote:

As the GH5 is a hybrid camera surely there should be constant aperture parfocal zooms for it. Various people have suggested there are software assisted parfocal zooms but I don't think I have really understood how to make this work. I have asked about it on various forums and there seems to be quite a bit of confusion. I wish someone could do a test. I have tried with an Olympus 12-40mm Pro but didn't get great results.

If you want a zoom lens that is almost parfocal, get a Cine lens. Even then it may not be perfectly parfocal.

Sigma statement

"In general, a perfectly parfocal lens production is nearly impossible. SIGMA goes through great lengths to reduce focus shift throughout the zoom range. However, as is the case with most cine zoom lenses, the SIGMA cine zooms are nearly parfocal."

In the old  days of film it was one of the golden rules, you do not zoom Whilst filming, perhaps we should sometimes stick to the rules of old 

It does look odd when you zoom whilst filming.

... 14 days prior to new firmware? Ok - you decision.

_vlad wrote:

... 14 days prior to new firmware? Ok - you decision.

Probably because of return deadline. He can always buy the camera back later if the firmware really make a difference.

MilitaryAttractions wrote:

I have 3 Olympus lenses and 1 Panasonic lens for my GH5. I use the cam primarily for filming. The Olympus ones including the high quality f2.8 m zuiko lenses are almost gaurenteed to lose focus when zooming. Example

Https://youtu.be/azkriMostH0

However my Panasonic 14-42 pz lens actually does an acceptable job as long as you are in good lighting. Is it possible my camera and lens are not communicating properly? I have yet to update the firmware on my camera but I browsed around and saw that you can update the firmware for both as some sort of combo? Looks complicated too, apparently u have to load the firmware on an SD chip. My Sony a6500 was a breeze to update.

Would really love some help. At an airshow and #$@&ing tired of getting great footage and then COMPLETLY losing focus for a couple seconds

The GH5's autofocus has improved quite a bit with the latest firmware update.

With that said, I agree with what others have mentioned about using parfocal manual cinema zoom lenses if maintaining focus in a scene like that is really important to you, or at least try the new Panasonic Leica 10-25mm f1.7. That's a nearly perfect video lens, especially if you have a GH5.