Moire
 

Oh my god, I just watched a DVD of my most recent wedding and the moire is REALLY bad. Scenes with greenery, leaves, rooftops just jitter and look horrible.

When the camera is being held steady, it's not there, of course, but when I was following the bride during the processional the grass and other fine details in the background shimmer and vibrate terribly.

The moire is noticable on bluray, but on DVD it's off the charts.

It was shot in 4k. Will shutter speed adjustments help in future shoots?

Or do I need to abandon 4k which is 30p and go with HD at faster frame rate?

Re: Moire
 

Huh? On the ax100? I"m not getting any moire at all. Can you show a short clip on vimeo?

Re: Moire
 

Not now, I'm trying to get this mailed. I've seen it on other projects on my TVand on a customer's tv as well but it's really bad this time. If I can find time I'll put something up later, thanks Noa.

Re: Moire
 

NLE and export/render options used were...?

Paul

Re: Moire
 

What was your shutter speed? I found in early tests that if you go above roughly 125, it shimmers badly. This also seems to be made worse if you have sharpness too high on the display TV. Everything I've shot with slower shutter seems to look fine, and I just turned the sharpness setting to zero on my Seiki 39...

Re: Moire
 

Dave, I suspect it was shutter speed related. I did not have shutter speed under manual control, I imagine, but will from now on.

Re: Moire
 

Bit rate for the DVD?

Was it downconverted to SD? Interline Twitter can result from software and not camera related.

Re: Moire
 

Bit rate same as always, standard. Video was only an hour long. Same problem on both bluray, USB, and DVD.

It's just much worse on DVD.

Re: Moire
 

It's not moire what you are seeing, that shimmering effect is something I have noticed as well when I first got the ax100 because I used it handheld at a photoshoot outside with trees and leaves in the background, a effect I managed to decrease significantly by choosing a other image preset on my tv that didn't have the sharpness dialed in so aggressively.
The ax100 resolves a lot of detail and I have a feeling there is also extra incamera sharpening going on, it looks like a full hd tv has problems displaying that very fine detail and I wonder is if 4K footage on a 4K tv would display that same jittering. Also when downscaling to dvd and if you have a scene with so much fine detail, incamera sharpening, a too high shutter and a tv with too high sharpening, that might lead to that "mess" you are seeing when you downconvert from 4K to dvd.
I now only use my ax100 for ceremonies, often set wide, or anything static so I can utilize it's cropping ability and for that purpose the IQ is fantastic, so much detail, even when downscaled, 4K cropped to 1080p size is still easy to match with my other 1080p camera's and it matches color-wise perfectly with my cx730's.

Re: Moire
 

Well Noa you are pretty much agreeing with what Dave said, and yes I hope shutter speed can fix it as Dave suggests. IQ is great with the camera and I'm very happy otherwise with images.

Re: Moire
 

It sounds like a problem with the software doing the downconversion from 4K to HD and DVD. Which may explain why the DVD has the effect worse than the Blu-Ray. It MAY be made worse by the camera having too high a level of sharpening set in a menu - with 4K you should need very little detail enhancement at all.

In general terms, to get a good downconversion the image needs to be softened *BEFORE* the downscaling step. Moire/aliasing is a result of putting too fine detail into a downscaling process - the principle is the same as in a camera sensor, though there "downscaling" is the process of sampling the image via photosites.

With much software, several processes happen in what seems to a user a single step - and same here, "downconvert" may be doing the downrezzing/downscaling separately without you being aware of it. Hopefully! It sounds as if this isn't happening here, and I can only suggest trying different software.

You may like to experiment on single frames. Downconvert a 3840x2160 frame to 720x480 in Photoshop and does it look the same or better as the downconverted video? If better, I'd regard that as proof the issue is a software one and unrelated to aspects of the camera.

Re: Moire
 

Thanks David.

I once tried using a full sized frame grab to eliminate the issue, an establishing shot, thinking that because the frame grab was still and not video the issue would go away, but it did not. On the final product it shimmered the same when I did a software zoom on the still image. So I'm thinking you are correct.

Re: Moire
 

I had a similar issue with this: I shot back in the day on a GH2 (that opening scene was one of the worst moments). The 1080 looked incredible, but the DVD had a lot of issues with the fine detail, including shimmering and moire.

I never solved it completely, but I tried the softening issue and it really the hurt the scenes that had downconverted to 480 without issue.

Ultimately I went with Red Giant's InstantHD (now Instant 4K) to downconvert and that did a much better job than the other options I tried. If you can spend the time, doing a downconvert frame-by-frame via Photoshop might work too, but definitely not as easy as a InstantHD downconvert in AE.

I really wish more people would request Blu-ray. I've only ever made DVD transfers that I thought were "passable" mostly because they are Standard Def after having seen the HD master.

Re: Moire
 

Thanks Gary.

Re: Moire
 

When I got my FDR-AX1 a year ago I did a lot of tests and found I could create and remove the shimmering depending on how I scaled especially when I viewed on the PC monitor. Just changing the size of the preview window in the monitor, especially in Vegas, made the shimmering come or go clearly a monitor scaling issue. I normally use Edius to edit the FDR-AX1 files on a 1920x1080 timeline with Lanczos 3 scaling and now do not see this issue monitoring. Output for DVD or Bluray is scaled yet again using TMPGenc with Lanczos3. Not sure if this will also work for X70/AX100 but does so for the FDR-AX1 almost all the time. You will not manage to remove for fine black and white stripped shirts etc though.

Ron Evans