5K 9:1 vs 4K 6:1

[Patrick Grossien]

Hi everybody, I don't have the time right now to perform the necessary tests, because this is one of these "are you free to shoot tomorrow?" situations. So I wanted to pick your brains and see what you think would be smart.

I need over one hour of continuous shooting and I was wondering what would render the best result.
The shooting scenario will be pretty dark but at least no wild, busy, patterned materials or tiny leaves.

Delivery for this project won't be over 1080p, but I'm interested in what would return the nicer 4K image in general.
I would instinctively pick 5K 9:1 over 4K 6:1 but maybe you guys would say otherwise?

How far would you compress the material before lowering resolution if shooting time is the most important part?
This is one of these times where I believe 4.5K would make my day! Hopefully Scarlet will gain those .5K steps sometime in the future.

 

[Keith Van Orden]

5K 9:1 definitely

 

[Daniel Stilling]

I bet you good money that in the vast majority of cases you wouldn't be able to spot any differences between 6:1 and 9:1 within the same resolution, so 5K 9:1 any time!!

 

[Marcus Friedlander]

I bet you good money that in the vast majority of cases you wouldn't be able to spot any differences between 6:1 and 9:1 within the same resolution, so 5K 9:1 any time!!

Definitely agree with this. Unless you are delivering theatrical, no one will notice the difference between 6:1 and 9:1

 

[Patrick Grossien]

Thanks guys. Exactly my thoughts.

 

[Milano Questa]

Maybe it's just me but i can always spot artifacts when going above 8:1

 

[Patrick Grossien]

Milano, so you'd rather step down to 4K?
(I was also thinking about pulling stills for web use as an option)

 

[Patrick Grossien]

Definitely agree with this. Unless you are delivering theatrical, no one will notice the difference between 6:1 and 9:1

What is the compression level where you guys would rather step down to 4K before using it? I've shot and seen good images at even above 9:1 but I've never been 100% confident to blindly go that route without tests.

 

[Ugo Del]

http://www.reduser.net/forum/showthread.php?130855-6K-5-1-or-5K-3-1
http://www.reduser.net/forum/showthread.php?124071-Compression-Wedges

Some interesting answers there, especially concerning the nature of the subject you are filming.

Also, from Gavin's test: "It's pretty obvious when looking at HSV that compression murders hue and saturation while preserving the luminance until last. So REDCode is a lot like going from 4:4:4 to 4:2:2 to 4:2:0. This is very bad for keying and I would really watch your compression at the cost of resolution for greenscreen work. If it's between 4k and no compression or 6k and high compression pick 4k IMO. You'll end up with very large splotchy chroma choise which will give you a lot of headaches. "

 

[Patrick Grossien]

Thanks Ugo, I totally forgot about the tests Gavin did.... this is perfect! (And it's a sticky! So d'oh!... guess it was too late last night)

Up to about 5:1 you won't visually see much if any of a difference in most shooting situations. If it's a really visually dense situation like a forest or a field of grass and also some big flat low detail areas like a plaster wall I would go 3:1 just because REDCode will suck up all of your data in the trees and then leave your flat plaster wall with like 20:1 compression and look like crap. As you can see in the wedges the first thing to go is hue and saturation, so if you're shooting something that depends heavily on hue and saturation like a Chroma Key then I would recommend edging towards lower resolution and lower compression ratio. Anything of 7:1 starts getting into "will probably have some form of compression artifact... just a question of how bad." Above 10:1 you also start to see chroma chatter and this kind of flickery look that I find very unappealing (The piano and tree shots demonstrate that).

And it seems that Patricks tend to have the exact same type of questions