GH4 GH5: High ISO Vlog = disaster (motion artifacts, etc)

F

filmguy123

Veteran
Pardon if this is common (vlog) knowledge, but I wanted to get some feedback. At first I thought I was seeing problematic artifacts with the IBIS, but after running some tests discovered that the ghosting I was seeing appears to be related to high ISO vlog.

Low ISO (400) vlog does not exhibit the problem, and high ISO (2500) cinelike-D seems to be ok, too.

But whether FHD 8-bit 420 or 4K 10-bit 4:2:2, if moving the camera around (even subtely) in high ISO (2500) vlog scenarios, you get a weird ghosting outline. And it becauses extremely exaggerated on darker areas of the frame.

Happens with IBIS on or off.

Is this to be expected? Is there a recommended max ISO for vlog?
 
Ghosting is usually an artifact from noise reduction; set the NR to minimal values and see if the problem persists (and yes, setting NR to minimal values will make the image noisier, I know; this is just a diagnostic check to isolate the issue).
 
Though I've installed the V-Log L license I haven't tested it yet. My guess would have been that the optimal EI would be a stop over it's base setting, so somewhere around ISO 200, but Barry's article about V-Log L on the DVX200 argues for ISO 400.

What I would be very hesitant to do is underexpose Log by pushing the EI much higher, & would switch to a flavor of Rec. 709 in those scenarios.
 
Bern Caughey said:
Though I've installed the V-Log L license I haven't tested it yet. My guess would have been that the optimal EI would be a stop over it's base setting, so somewhere around ISO 200, but Barry's article about V-Log L on the DVX200 argues for ISO 400.
Click to expand...

I was surprised today to find V-Log base ISO is 400. No 200 available. It is available in the other profiles.
 
Barry - NR was set to -5. I also tested at 0 with the same results. No problem in Cinelike D. No problem at base ISO of 400.

And correct, vlog base ISO is 400 and you can't go lower.

So, is it safe to say then that vlog shouldn't be used at higher ISOs? Is that just going to be common sense?

Really looking forward to some more technically inclined/experienced folk testing these findings here so we can develop some best practices. Really glad I found this out now and NOT on a shoot, as the artificating is not minor - it's severe ghosting and would really mess up any movement (even somewhat subtle movement).
 
If EI 200 turned out to be the optimal basesetting for V-Log L it appears a exposure compensated LUT could be loaded into the camera so the EVF/LCD wouldn't display a hot image.
 
Last edited:
visceralpsyche said:
This is a known bug with v1.0 of the firmware. I've been directly in contact with a Panasonic representative after filing a bug report, and they have let me know that Panasonic is aware of the issue and are planning a fix for a future firmware update.

HTH

Paul :)
Click to expand...

Cheers Paul. Good to know.
 
filmguy123 said:
Pardon if this is common (vlog) knowledge, but I wanted to get some feedback. At first I thought I was seeing problematic artifacts with the IBIS, but after running some tests discovered that the ghosting I was seeing appears to be related to high ISO vlog.

Low ISO (400) vlog does not exhibit the problem, and high ISO (2500) cinelike-D seems to be ok, too.

But whether FHD 8-bit 420 or 4K 10-bit 4:2:2, if moving the camera around (even subtely) in high ISO (2500) vlog scenarios, you get a weird ghosting outline. And it becauses extremely exaggerated on darker areas of the frame.

Happens with IBIS on or off.

Is this to be expected? Is there a recommended max ISO for vlog?
Click to expand...

Just tried the different movie modes. In 4K 10-bit 4:2:2 25p the ghosting artifacts are really pronounced. All the other modes (50p, 4:2:0, 4K or FullHD) show ghosting in high ISO values too. But it looks more compact, almost like motion blur, which is okay for me. However I wish this „look“ would apply to 4K 10-bit 4:2:2 25p as well.
 
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