As per my suggestion to Etc, I'd personally say record in HD. Everything you may gain from super sampling down from 4K will be more than lost by the relatively higher compression (compared to HD) that onboard on the A7s uses.
If however you were pushing out uncompressed to an external recorder, 4K to HD wins by a mile
That's not true the H264 codec as well as any intra codecs are not optimised for 4K and perform worse than what they do for 1080p
The downscaling theory is based on the resolution available and the theory that downscaling a 4:2:0 color space becomes 4:4:4
The first is true only for cameras without full sensor readout and the second is just not true
Well. I did some test.
I recorded in a green screen set to test Chroma Key and I also recorded a low light shot.
All clips recorded with the Pana12-35mm. Iso400. 1/50s. I shot 4 different clips in each test:
-4K 25p 100Mbs
-HD 50p 200Mbs
-HD 50p 100Mbs
-HD 50p 50Mbs
Curiously I didn't notice much difference in the chroma key test. They all look pretty much the same. I definitely have to do further tests.
Let's get into the low light tests. Some stuff came up that really don't make much sense to me.
All clips recorded with the camera on a tripod, same duration (5 secs), same scenario, lighting, aperture...
4K size: 55,1MB
HD200 size: 28,6MB
HD100 size: 55,8MB
HD50 size: 33MB
When I saw the HD200 size in my computer explorer I had to double check all the clips in the camera because I couldn't believe it.
4K has double resolution than HD200, but half the frame rate, and half the bitrate. So in a rough calculation I would expect the HD200 clip to double the size of the 4K file. But, since compression is not linearly proportional to resolution and it has to do a lot with spacial and temporal redundancy ( bitrates are variable too), I'm really not surprised by this data.
What really surprised me is when comparing HD200 with HD100!!!!!!. Has no explanation to me. All the clips are in the same container and are supposed to be compressed by the same codec!!!!
Anyway, those are just number so far.
So I imported all of the clips into Adobe AE and pushed the signal to the extreme. I applied the same correction to all clips, obviously. I also downscaled the 4K clip to HD after correction.
Same cropped area of each clip:
Depending on the frame you analyze of each clip you might see slightly quality difference between HD clips, but to my eyes the all look pretty much the same junk.
I expected some evident difference between them, but once again compression algorithms are beyond my understanding and I guess that probably I would notice some difference in terms of quality under some other circumstances (high lights or high detailed images).
BUT what I really consider as fact is that the 4K clip has a much better behavior than any HD file. For me it really confirms what I read about the convenience of recording in 4K in the GH4 even when the final output is HD.
Take a close noise in the door and in the AC switches. Here is no so evident, but in my work computer I can also see a great difference in the greens gradient of the chroma board. Is much less noisy in the 4K clip.
I totally agree with you. I never tried to deny the obvious effects of different shutter speeds. I just try to reframe the apparent need for setting up something as "the normal thing". I think don't waste time when arguing... I learn a lot. I do so with the purpose of being convinced rather than be convincing. Thanks
For what it's worth, my old Sony Z1P HDV would white balance down to 23m (pointing it at the palm of my hand). Sometimes I would need to point it at the sun to get a fix if I was close to the depth limit. I was happier with the Z1P underwater manual white balance results than I have been so far with the GH4, but I haven't shot a lot of available-light stuff yet. It's difficult to say exactly what bothers me about the GH4 u/w white balance. The footage might just be lacking saturation, especially in the blue water. It's not that bad though.
p.s. I could manually white balance my VX2000 at 50m (in available light with a blue-water filter)!
I found all the MWB results really good.
Since it was not my camera I didn't want to mess much with image configuration and it is true that I found the image a little bit unsaturated but when I went to color grading.... great behavior!!!.. contrast, saturation with no artifacts. It is also tru that I will have to upgrade my computer because 4K really slows down the whole post-production chain!!!!!
I have to do post stabilization since I'm not that expert in diving yet (has less than 200 dive). Camcorder offer better image stabilization. I used GH4 underwater before the the image stabilization is not much different from the LX100, it's mostly all about the diver.
Back button focus mean you have the camera setting in Manual Focus mode, then use the AE/AF lock button to set initial focus, then start recording. By having the camera in Manual Focus mode, you get the focus peaking feature.
Ok, I get it. I suppose that is the best procedure in the LX100. Peaking is a good invention. In the GH4 you can get extra help just by pushing one button to access the magnified picture. Can you configure the LX100 in the same way? Don't be so modest, I know quite a few guys that feel experts with less than 50 dives. I have a lot more dives and I'm sure image stability is not only a matter of experience. The Tinier, the shakyier
Great footage and editing!!!!. God duration. Good music, great timing. All critique asides, I really envy you
I think Drew's got the point, but I'd add (under my personal opinion, of course):
- Color correction on the wreck's bow (1:24). More contrast, get rid of excess of cyan
- Take the Trigger fish shot out (1:26). The rest of the video doesn't deserve this.
- 1:37.. out too! (don't like the composition)
- Put the two shots of the Thiselgorm trucks together.
- Color correct & stabilize the Whale shark (2:17)
- 2.39 shot out!.. It doesn't say much.
- Shorten or "roll edit" a bit the lion fish shot. Don't let the shadow get into it's face (3:01)
- Change the ending shot for a better one!. Or just leave the sunset last timelapse for the end.
I hope I didn't look rude and I could express well. I'm Spaniard and my english is far to be perfect.