5K at 8:1 or 4K at 5:1?

[Stephen Pruitt]

Hi all. . .

I've been shooting my features at 5K 8:1, but now wonder if I should've been shooting 4K at 5:1. Which setting will yield the lowest noise? I can see it going either way, but I really don't trust my failing eyes.

Super thanks!

Stephen

 

[Karim D. Ghantous]

I don't know if this directly answers your question, but:

[Darius Wolski] shot Prometheus in 5K at 5:1 compression (occasionally switching to 3:1 compression for scenes with very fine detail, like water or foliage),

https://theasc.com/ac_magazine/July2012/Prometheus/page1.html

Maybe preserving motion is more important than more detail? Worth a thought. There must be a sweet spot. Some people, I believe, shoot high compression in 4K or 5K if they know that the output is going to be 2K anyway. This means that you're always shooting the full frame, making everything easier.

 

[Ignacio Aguilar]

For feature films, specially when dealing with low-light scenes, I'd shoot at the lowest compression that your production can afford.

 

[Mike P.]

5K for sure.

Even if it wouldn't be better for noise (which, anecdotally, I think it would be, unless looking 1:1), you'd have the benefit of larger sensor, 5>4k downscale, and/or a guilt-free reframe/stabilization buffer. Don't forget 4k = 8.8mp, while 5k = 13.8mp... that's just shy of 60% more pixels, which is a huge amount when you consider they'll both end up at a 4K finish. Further, any differences between 8:1 and 5:1 (even at the same resolution) will get absolutely hosed in the delivery render/codec.

Prometheus, along with having a huge budget to afford whatever storage they wanted, was an vfx heavy movie so that extra couple compression points may have helped the vfx dept (who would probably be working in uncompressed frame sequences), but I doubt you'd see the difference on screen in even the least compressed delivery method.

 

[Patrick Tresch]

For feature films, specially when dealing with low-light scenes, I'd shoot at the lowest compression that your production can afford.

And I would say "above all with the most of resolution you can have" allways good for downscaling and denoise ;-)
8:1 is really a good compression, I would be more worried above that (10 or 12:1) and it depends how much noise you have. 3200iso or 12800?

 

[Björn Benckert]

Resolution always wins.

So always opt for more resolution instead of lower compression. Same weight files at capture 8k vs 4k... 8k can be half the weight of the 4k file and still look tons better. Very few producers and others understand that this is the case. It's actually cheaper to shoot higher resolution as the files does not need to be so heavy.

 

[Stephen Pruitt]

8:1 it is gentlemen, and thank you very much for your expertise!

Stephen

 

[Karim D. Ghantous]

Resolution always wins.

So always opt for more resolution instead of lower compression. Same weight files at capture 8k vs 4k... 8k can be half the weight of the 4k file and still look tons better. Very few producers and others understand that this is the case. It's actually cheaper to shoot higher resolution as the files does not need to be so heavy.

I think I get it. Bigger files compress better, right? It's just logic. I should do an experiment...

 

[Les Hillis]

I know the original question was about noise, but I think the effective FOV/crop factor difference between 5K & 4K would be more of a decider for me than the differences between the given resolutions or compression ratios.

 

[Andreas Mendritzki]

I think the link is dead, but Offhollywood had a great comparison on their blog that I always used to refer people to. It was a side by side shot at 8k at X:1 vs 6K at Y:1 where the two files had almost identical bitrate/filesize. The 8k file at higher compression resolved more detail.