GH5 GH5 Moire

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Francesco Dal Bosco

Active member
How about the strong amount of moire the GH5 exhibits? I've discovered this problem today after a brief test and I'm very disappointed. My GH4 was way better in this respect. I'm wondering why Panasonic removed the anti-aliasing filter. The majority of Panasonic users
usually set sharpness to -5 so this move don't seem a brilliant idea to me...
 
Francesco Dal Bosco said:
How about the strong amount of moire the GH5 exhibits?
Click to expand...

What settings are you using ?

My GH4 was a moire-magnet when shooting in 1080p, so I switched to shooting everything in 4K because of this.

With my GH5, I have seen a tiny bit of moire in an electronic flat-screen sign when shooting a cityscape shot. Everything else in the wide shot was perfect, except for the sign. I plan on going back to the same location to shoot it with my GH4 to see if the GH4 shows the same moire.

Overall I've been very happy with the lack of moire with my GH5. I am shooting everything in 10-bit formats. No idea if this makes a difference.
 
My settings are 4k 25p 8bit 100Mps. Maybe 10 bit it's better, I don't know. I'm getting huge moire in some critical situations. In the very same situations the GH4 was perfect,
 
The GH4 was better because it didn't do any scaling. It pulled 4k off part of the sensor in a 1:1 pixel ratio, but this meant there was a slight crop (around 2.4x). The GH5 scales 4k down from the full sensor readout, so less crop, but you can get moire.
 
Not entirely sure I would say the majority of users set the sharpness to -5 on the GH4.

The GH5 got rid of the low pass filter so the stills would have even more natural detail. This is a common practice of many DSLR cameras and the price we pay for using a hybrid camera. It has to excel at both stills and video. It was a very good decision by Panasonic because it really boosted the stills quality and their new scaling method for the most part eliminates most of the moire issues. It can still happen but thats the price we pay for shooting video with a DSLR.

It isn't that the GH4 or GH5 is better or worse just that they respond differently to different types of detail. There is a 4k ETC mode on the GH5 you can try that does no scaling at all and takes the 4k center at 1:1 just like the GH4 did when shooting 4k video. Maybe that will help this particular situation.
 
Yes Batuta, you're right. The lack of anti-aliasind filter doesn't help too I think. This camera is a great tool in every other respect, color rendition, stabilization, codec and so on nevertheless this is a big issue (in some situations) in my opinion. I remember when Canons were plagued by moire and aliasing whereas the GH2 was almost perfectly clean.
 
I had the same experience with moire and also aliasing on the GH5. After using the GH4 for three years, I was excited to upgrade to the GH5. Everything about the specs looked great, and I really like using inconspicious cameras to shoot doc footage. But after purchashing the GH5 and using it for a few days with native Panasonic lenses, I found the moire and aliasing so problematic that I returned the camera. The image quality of the GH5 is quite different from the GH4. It's way sharper. That can be a good thing, but to my eye it looked too sharp. I've experimented with Black Pro Mist filters and other diffusion filters, but they can introduce their own issues. So now I'm considering what my next camera system will be: Sony A7SII? Canon C200? Canon 5D Mark IV with Canon Log? Panasonic EVA1? I was reading an interview with filmmaker Joan Churchill recently and she said "All cameras are compromises. We match the camera to the moment and are always on the lookout for new options." Well said.
 
Batutta said:
The GH5 scales 4k down from the full sensor readout, so less crop, but you can get moire.
Click to expand...

At some point in the future Panasonic is supposed to release a firmware update that includes "open gate" recording, where the full sensor image is recorded at it's native resolution and you would then crop this in post. If this happens it may bring us back to the equivalent of GH4 1:1 pixel ratio recording and eliminate pretty much all moire from the GH5.
 
Thank you guys. Thomas, yes the tele coverter helps so in some situations it can be useful (but my disappointment still remains). On the other hand, I don't see a real alternative for this camera so I have to accept this limitation.
 
Francesco Dal Bosco said:
Thank you guys. Thomas, yes the tele coverter helps so in some situations it can be useful (but my disappointment still remains). On the other hand, I don't see a real alternative for this camera so I have to accept this limitation.
Click to expand...

Another option is to add a filter to the front of the lens to slightly soften the details and mimic a low pass filter. Not the same thing but it might be enough in your situation.

Yes it is a bummer but its the reality of shooting with hybrid cameras that need more pixels for stills. If it was up to me I would have preferred the GH5 with less pixels so it had just enough for 4k video which could have slightly helped the sensitivity and dynamic range. Alas I doubt we will ever get such a thing so unless we move to a dedicated video/cinema camera it is what it is. You either have crop or a less than optimal method of scaling. I had hoped the method of scaling on the GH5 would be enough to combat moire but it is starting to sound like that may not always be true.

The lens choice may affect the potential for moire as well. The sharper and more detailed the image the more high frequency detail can freak out.
 
Thank you Thomas. It's always a pleasure to read your posts. What I need is a hybrid camera, light and versatile, good enough for video and stills. I use this kind of camera mainly for documentary works, where lightness and discretion are important factors. The GH5 could be almost perfect in this respect but the moire and aliasing problem I've surprisingly discovered in video mode is in my opinion a step back compared to the GH4 in terms of picture cleaning. Therefore I think this camera is not well balanced among video and stills features. It's a bit strange that not long ago the moire issue was considered one of the key problems to be adressed for video oriented dslr cameras.
 
Francesco Dal Bosco said:
How about the strong amount of moire the GH5 exhibits? I've discovered this problem today after a brief test and I'm very disappointed. My GH4 was way better in this respect. I'm wondering why Panasonic removed the anti-aliasing filter. The majority of Panasonic users
usually set sharpness to -5 so this move don't seem a brilliant idea to me...
Click to expand...
Could you dropbox a few seconds so we can take a look?
 
Since getting the GH5 on release I have shot hours of footage, close to 400GB. Addmitedlly most of it in 10-bit, but I have yet to see a single instance of moire.
 
Francesco,

Are you sure the moire you're seeing is actually in your footage and not just an artifact of how you're viewing it? Improperly scaled video on a monitor can easily have moire. You would need to look at your footage 1:1 to be absolutely certain.

And some monitors and software do scaling better than others.

Sharing a clip as Cary suggested would be the best way of getting to the bottom of your issue.
 
What you are seeing is probably moire/aliasing from down scaling to a lower resolution than UHD, which I could also see on a FullHD 1080p screen.

To simulate a pixel to pixel (1:1) viewing with no scaling at all try to watch a FullHD 1080p crop of the video.
You should also try to convert/export the video to a 1080p file using a software with good up and down scaling algorithms.
In those cases you shouldn't see this phenomenon.
 
Thomas Smet said:
The GH5 got rid of the low pass filter so the stills would have even more natural detail. This is a common practice of many DSLR cameras and the price we pay for using a hybrid camera. It has to excel at both stills and video. It was a very good decision by Panasonic because it really boosted the stills quality and their new scaling method for the most part eliminates most of the moire issues.
Click to expand...
It's a common misconception that eliminating the OLPF increases the "natural" detail of a demosaicked image. What it actually does is spray ultra-fine edge details across the image, but corrupted in a spatially inverted manner. The resulting edge scintillation appears to enhance sharpness, but it's not natural at all, it's a particularly gritty form of modulation distortion produced by violating the sampling theorem with cavalier disregard for the sensor's Nyquist frequency. In other words, it's an insidious contamination that cannot be squeegeed clean in post, at least not without permanently degrading genuine details as well.

The GH5 has a 20Mpix image sensor and lacks an OLPF, compared to the GH4's 16Mpix sensor with OLPF. In this regard, Panasonic is following Nikon's example of omitting the OLPF on recent cameras that use sensors higher than 16Mpix. The theory is presumably that past a certain Mpix threshold, ultra-fine aliasing artifacts are no longer discernable (in most cases...). However, Nikon seems uncertain whether 20Mpix is enough, as they omitted the OLPF in the D500 but retained it in the D750. And it's not because the D750 is full-frame - aliasing is strictly a matter of sampling granularity rather than image sensor size. Here's detailed info from Nikon on OLPF issues:

http://www.nikonusa.com/en/learn-and-explore/a/products-and-innovation/moir%c3%a9-false-color.html

Back to the GH5, while its lack of an OLPF makes its still shots even more excrutiatingly "sharp" than the GH4, that's not likely the culprit producing moire in 1080p and 4K video modes. What's critical there is exactly how Panasonic demosaicks the 20Mpix sensor down to video resolution. We don't know the sticky details of this algorthm, as neither Panasonic nor any other camera manufacturer are willing to disclose their technical trade secrets. But with moire, the bottom line is what you can see with your own eyes, particularly while panning. For those who want to see what the GH5's moire actually looks like, use a sharp lens to pan across a sinusoidal Zone 720 resolution chart like the one below, and view it at 100% magnification on a one-to-one pixel monitor:

http://www.bealecorner.org/red/test-patterns/Zone720-sine-g22-b.png
 
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I have been shooting with my GH4 for several years now. I like 4K mode. But I sorely miss 60fps and have been saving up for the GH5. I mainly shoot nature docs where getting good detail is critical. My latest is below. Due to the moire issue with the GH5 is it still a good choice?

http://vimeo.com/226215943
 
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Cary, 4k resolution on vimeo. The original file is 4k too. I see the problem perfectly on my 27' Imac. On my FullHD TV set is even worse. Maybe it's a downscaling issue but I need to downscale my 4k footage to 1080p. I never had any problem with the 4k downscaled GH4 footage.
 
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