[Chris Walker]

I wouldn’t say the LX100 is primarily a stills camera. It’s basically a compact version of the hybrid, very video-friendly GH4, but a bit more stills oriented and without some of the more advanced video features. As with the GH4 and other hybrid mirrorless and DSLR cameras, I know that the full frame image is shrunk down using various techniques to make the much smaller 1080p image. Whereas with the 4K a smaller portion of the sensor is used and the 4k image is not shrunk down at all with the GH4, and only slightly with the LX100. I also know that using a smaller portion of the sensor will make any noise/grain appear larger, even if the resolution is higher.
But most people mixing 1080p and 4k on a 1080p timeline are using 1080p and 4K footage from exactly these types of cameras, and I haven’t come across any complaints on the various forums about the 4k looking worse rather than better than the 1080p because of this enlarged noise/grain issue, even when cropping the 4k footage, so I assumed the noise/grain increase with the 4k was quite small. That’s why I was surprised when the increase seemed pretty dramatic to me.
So I did some tests. I shot a scene at ISO 400 and then ISO 3200, which is about as high as you want to go with a micro four thirds sensor, correctly exposed and focused and keeping the exposure constant by changing shutter speed. First 1080p 60fps, using the “standard” profile and default settings. Then the exact same scene and lighting and exposure and ISOs using 4k 30fps, standard profile. First with default settings, then with everything at -5, then with everything at -5 except noise reduction at +5. Then I put the footage on a 1080p 30fps timeline in fcpx, with the 4k clips spatial conform setting at “none” and scaling set to 50%, so they fit the frame exactly. Some of the 1080p clips were deliberately zoomed in tighter so I could scale up the 4k clips to match the framing, and those 4k clips were scaled at 80%.
Now, since I was still at well under 100% for the 4K, I thought that even the 80% 4k shots should still look better than the 1080p. And I did find that at 400 ISO, all the 4k shots looked more detailed and generally better, even though at 80% I definitely noticed some significant grain/noise creeping in. But at 3200, while the image was still better overall at 50%, the increased grain was much more apparent, and with scaling up to 80% the noise was so much stronger that even though the detail was better I thought the image was worse over all. The 4k shots with everything dialed down to -5 looked best in every case, after I color corrected and in some cases put back in some sharpening, but with those 3200 ISO shots about the best I could do was add in a little gaussian blur to make the grain less apparent.
So is the lesson here simply that if I want my moderately cropped 4k to look better than my 1080p I need to either use a larger sensor or stay below 3200 ISO? Or are there some other settings I can use to decrease apparent grain in 4K? There are always denoisers like Neat Video, but I’m hoping not to have to resort to using those..

[Chris Walker]

1080p 60fps is AVCHD, MTS files that use a directory in a folder called “private”. Panasonic GH3 and LX100.
4K 30fps is mp4 files that can stand alone without a directory, Panasonic LX100.
Hmm, I didn’t test avchd vs mp4 to see if one stabilizes better than the other….

[Chris Walker]

I will provide samples later, but my main question is why does an ALMOST IDENTICAL shot usually (but not always) stabilize much better, if shot in 1080p 60fps. I have done multiple tests shooting the same handheld dollying or tracking shot, once in 4k and once in 1080p 60fps, and the 4k will usually not be adequately stabilized even at max settings, while the 1080p usually comes out silky smooth at default settings. If it’s simply that 60fps footage can be more easily stabilized (more frames to work with), then why do SOME of my 4k, 30fps shots stabilize quite well, even when there is a lot of camera movement? This issue of stabilization SOMETIMES working well but most of the time not is what is driving me crazy. With 1080p, I can almost always predict whether a shot can be decently stabilized, but not at all with 4k.

Of course getting the most stable footage possible to begin with is important, but again, using the same handheld shooting style that I’ve always used with 1080p 60fps, 90% of my shots are successfully stabilized. With 4k, less than 25% are successfully stabilized, and the percentage doesn’t seem to improve much even when I try to be much more careful and deliberate with my movements.

Also, I wonder why I haven’t found anyone else at all talking about this problem. Some weird quirk with my particular copy of fcpx?

[Chris Walker]

I realize that a big camera jerk can require a big zoom-in, but with 4k that big zoom-in should still allow good sharpness on a 1080p timeline. The question I need answered is why a 1080p, 60fps shot smooths out nicely while the almost identical shot in 4k 30fps doesn’t smooth out at all even with stabilization settings maxed out. Can 30fps vs. 60fps really make that much of a difference? I’ll try stabilize some 30fps 1080p shots and see if I have the same problem..

[Chris Walker]

The clips are mostly 4-8 seconds long. I get the usual message that it’s analyzing the motion, takes a few minutes at most, then a shorter time to render. The rendered clip sometimes shows some degree of smoothing, sometimes no change I can discern. Same type of shot done in 1080p 60fps, smooths out much better almost always. I hope this doesn’t mean I have to avoid handheld 4k shots where I’m doing gentle moves like dollying in a couple of feet. I’m almost always able to stabilize those very nicely with 1080p 60fps, and was looking forward to being able to do even better stabilization with 4k since I could use maximum settings and not worry about a substantial digital zoom being applied.

[Chris Walker]

Now I have also tried stabilizing in a 4k 30fps timeline. Still doesn’t work. What’s going on?

[Chris Walker]

By the way, after writing that post I read about setting spacial conform to none and tried that, with the scale at 50%, but, stabilization is no better.

[Chris Walker]

No, it’s definitely 1080 in the timeline. I’m thinking I have to do a custom encode rather than automatic if I want a larger file.

[Chris Walker]

Thanks to all for the help; trashing preferences did the trick! I was really getting worried when even without any events or projects it was still slow…

[Chris Walker]

I used a company called Drive Savers based in California. Cost me a bundle but they were able to recover almost everything. Some footage from a second camera was not recovered but I was able to work around that. Expensive lesson!