Shooting 3K for DCP 2.40:1 a good idea?

[Martin Beek]

I am considering shooting a feature in 3K for a number of practical and obvious reasons such as SSD media, playback speed on set, rendertimes, et cetera. I have a primes kit, ranging from 14 to 85mm that gives me the fov i want, considering (and compensating for-) the crop factor. So no problem there.
The release format is 2048x858 (2K DCP scope).

But, after reading some threads about The Girl with the Dragon Tattoo's workflow, i came up with (maybe) another great opportunity when shooting 3K for 2K output.

Being a kind of el-cheapo "David Fincher / Lightiron solution", i'm thinking of the following workflow, to allow for reframing and stabilization:

- shoot in (Scarlet) 3K
- downscale the 3072x1620 footage to 2400x1000
- edit with a 2048x858 project setting, allowing for reframing and stabilization of the footage, having approx 150 pixels to play with.

I have two questions.

1) Is shooting 3K a bad idea, quality wise? Any experiences with this?
2) Does my hypothetical workflow above make any sense?

Pros, cons and any other piece of advice is much appreciated.


Martin

 

[Matthew Scott]

3k is awesome and so are your workflow points...except why downscale it? Leave it at 3k so you have more to stabilize/pan/scan!

 

[Paramon Ivanovich]

I wouldn't do that, even if I would have Epic and only one 64gb mag I'd shoot 5K 6:1,
if this is not an event or sport you always have time to stop, back up the footage , check your lighting, "dry run" the scene with the actors,
with 3K you gona loose a lot of sensor real estate and limit your lenses choice;
get extra mag(s), get a dedicated body for constant back up, even on a low budget there are always people willing to pledge their time and effort for the sake of art.
but that's me

 

[Mitch Pierias]

My scarlet is on a small feature at the moment in the bushland of Australia with only one 64GB card. They are having no troubles backing up through firewire on set because it's taking around the same time to transfer 64GB as it does to setup a shot.

I thought of shooting 4K with guides for 3K. I could frame for 3K and then when I get in post I would have extra data outside my shot for stabilizing and what not.

 

[Rodrigo Prata]

As for real time playback on set. You can play back 4K footage real time on the most recent Apple laptops if you leave the resolution at 1/4 on REDCINE-X pro for instance.

Also, Unless you are planning to shoot a considerable amount of HDRx or Slow Montion, I would shoot at 4K, the size of the files will not be so much smaller at 3K (specially if you shoot at lower compression ratios). But that is just me and of course 3K is also very good.


Cheers

 

[Noah Yuan-Vogel]

Why shoot 3k? If it's about space, why not just shoot 4k with higher compression?

Reasons not to shoot 3k
-4k has more latitude and sensitivity by up to 1 f-stop
-4k with higher compression will likely give you generally better image quality than 3k with lower compression because compression gets more efficient with higher sizes and the "compression" of throwing away 1/2 of your image is about as inefficient as compression gets.
-3k minus 25% recorded lookaround could start looking a bit soft scaled to 2k, definitely softer than 4k scaled to 2k

There are other reasons but these are the first that come to mind.

On the other hand 3k has the benefit of supporting HDRx or 48fps on Scarlet if you need those.

 

[M.D. Hilton]

Take a day and shoot a scene from the film with the workflow you suggest and see if you are happy with the results. A day shooting a scene and another day doing the post isn't much time to make sure you have the right workflow for you before you set out to make a feature.

My personal feeling on the matter is I'll always shoot in the highest resolution possible and always use the best compression available to me with the Scarlet (4k and 6:1). Start with the best available image quality and move on from there.

 

[Antony M]

Reasons not to shoot 3k
-4k has more latitude and sensitivity by up to 1 f-stop

Really?

How does that work?

If you crop the sensor you lose 1 stop of sensitivity???

 

[Matthew Scott]

I have two questions.

1) Is shooting 3K a bad idea, quality wise? Any experiences with this?
2) Does my hypothetical workflow above make any sense?

Pros, cons and any other piece of advice is much appreciated.


Martin

Shooting 3K is not a bad idea. Quality wise it's awesome. Yes, 4K will look sharper and seem to have more detail and 5K even more so (once down-scaled to 2K). Is it always better to shoot 4K/5K? Yeah sure it is, but I love breaking rules and pushing boundaries. So, space on your SSD media, playback speed on set, rendertimes, compression ratios and frame rates (not to mention HDRX) are all better at 3K. If you're willing to invest in/borrow stuff to solve your initial concerns, then the choice is easy - 4k all the way. But, I wouldn't just rule out 3K because 99 percent of the people here will tell you to. 3K is still an admirable format and I'm personally loving the option to be able to shoot it.

 

[Dustin Cross]

Do a test. 3k is not bad. 3k will create some challenges. Lots of the info in this thread is wrong.


Dusty

 

[Christian Jadot]

I actually consider the Scarlet a 3k camera with a 4K option.

For the reasons stated above. When I know I need an extremely detailed/wide/stablized shot, I go 4K (QHD), however 3K is my primary mode for shooting. 3K is just more versatile in the Scarlet.

I know many will disagree, since reading the Specs on Nov. 3rd, I have had this mindset that 3K is the way to go with the scarlet for those on a budget.

 

[Patrick Tresch]

Really?

How does that work?

If you crop the sensor you lose 1 stop of sensitivity???

The statement he made was really misinterpreting.

I think he wanted to say that cropping the sensor will increase the visibility of noise as it is a zoom effect and therefore, in his point of view, increases the noise presence of what he calls 1 stop...

In the feature I shoot today I mainly use the 5k resolution to be able to go to higher "ISO". Mainly shooting above 1280iso like 2000 and 2500. The g(R)ain is really small at that resolution.

Now telling that resolution increases dynamic range is another story...

Pat

 

[Omar Al-Masab]

if you are concerned with data rate I would crank up the compression rather then knock down the resolution.
higher compression rates are rather good. only in noisy footage and high frequency shots less compression would come in handy.

 

[Noah Yuan-Vogel]

If you crop the sensor you lose 1 stop of sensitivity???

Here are a few ways of thinking of it from my understanding of how this works:

-If you crop from 4k to 3k, all else being equal, your camera system is now exposed to half as many photons, or one stop less light total, this is not immediately obvious in the image but with equal photosites and equal delivery/monitoring, your noise level will appear up to one stop higher due to greater magnification/less reduction for viewing.

-Another way to think of it is, if you shoot 2k in camera and compare to 4k downscaled to 2k, the 4k downscale will have the benefit of combining data from 4 pixels at a time to create the final 2k pixel. If these original pixels have noise that causes a luminance fluctuation of 4% of the sensor's range, and the 4k pixel that is getting downscaled to 2k and getting averaged (not exactly averaged, but nearly depending on downscale algorithm) will have a fluctuation of only 1% of the sensor's range, 1/4 as much noise, or 2 stops less noise. This is similar for 3k but it is half the difference or 1stop.
If you are not familiar with this improvement in noise for combined pixels, think of it this way. If the noise for one pixel is equivalent to 10 electrons, averaging two pixels together will still give you a noise level of 10 electrons but now the total possible number of electrons is doubled, so relative to the new combined-pixel's possible range, the noise level of the combined pixel is half that of the single pixel or 1 stop less.

 

[Noah Yuan-Vogel]

Now telling that resolution increases dynamic range is another story...

Dynamic range is determined by white clip and black noise, white clip is constant, but black noise is heavily dependent on resolution and therefore dynamic range is dependent upon resolution.

Pixel noise means very little alone since pixels are not used alone, it's the array that makes the image.

 

[Mike P.]

You also have access to 24fps HDRx at 3k too for higher-than-normal dynamic range scenes.

I would definitely do a test between 3k at 6:1 (or whatever you plan on shooting at) and 4k at 12:1 (or double the compression you plan on shooting 3k at.) And then downscale to your delivery resolution (2k or 1080p) and compare those. I get the feeling that 4k at 12:1 will take up less space and look sharper/better than 3k at 6:1 when viewing at the 2k output. Honestly, the only reason I would consider 3k or 4k for a 2k delivery would be based almost entirely on whether I thought I needed HDRx/48fps or not; those two things have a direct affect on creativity. If it's just a space thing, I'd be bumping up the compression ratio knowing that even a Blu-Ray deliverable probably wouldn't be able to pick up the differences between 6:1 and 12:1... If you're going to web, I'd rock 18:1 and not even think twice about it.

The other thing to consider is, at 4k even with a higher compression ratio, you've got a lot of resolution to spare. Using more aggressive noise reduction and/or sharpening when you process the footage will probably look better than it would on 3k footage and it would help compensate a lot of the higher compression ratio you'd have to shoot at with 4k.

So, yeah, start testing things out (please post your test .r3ds too, so the rest of us can try at home!)

 

[Martin Beek]

I'd like to thank everyone for the insights and advice. I've still not decided which route to follow, but i lean towards shooting 4k and half-debayer-premium to FCP.
Thanks again - i come from 35mm film and this board is invaluable to me!


Martin.

 

[Martin Beek]

Here are a few ways of thinking of it from my understanding of how this works:

-If you crop from 4k to 3k, all else being equal, your camera system is now exposed to half as many photons, or one stop less light total, this is not immediately obvious in the image but with equal photosites and equal delivery/monitoring, your noise level will appear up to one stop higher due to greater magnification/less reduction for viewing.

-Another way to think of it is, if you shoot 2k in camera and compare to 4k downscaled to 2k, the 4k downscale will have the benefit of combining data from 4 pixels at a time to create the final 2k pixel. If these original pixels have noise that causes a luminance fluctuation of 4% of the sensor's range, and the 4k pixel that is getting downscaled to 2k and getting averaged (not exactly averaged, but nearly depending on downscale algorithm) will have a fluctuation of only 1% of the sensor's range, 1/4 as much noise, or 2 stops less noise. This is similar for 3k but it is half the difference or 1stop.
If you are not familiar with this improvement in noise for combined pixels, think of it this way. If the noise for one pixel is equivalent to 10 electrons, averaging two pixels together will still give you a noise level of 10 electrons but now the total possible number of electrons is doubled, so relative to the new combined-pixel's possible range, the noise level of the combined pixel is half that of the single pixel or 1 stop less.

Very clear explanation! Makes a lot of sense. Thanks!

 

[Paramon Ivanovich]

But in any case Martin,
please keep us in the loop, it is very interesting and always educational to hear and see different people opinions and results;
best

 

[Steve Sherrick]

My scarlet is on a small feature at the moment in the bushland of Australia with only one 64GB card. They are having no troubles backing up through firewire on set because it's taking around the same time to transfer 64GB as it does to setup a shot.

I thought of shooting 4K with guides for 3K. I could frame for 3K and then when I get in post I would have extra data outside my shot for stabilizing and what not.

Wow, that's one of the scariest scenarios I can think of. Hopefully that 64GB SSD behaves or there will be a lot of people standing around. If you had said two 64GB cards, I'd still think it was cutting it close but certainly doable, especially if the budget is very small. But one SSD? I have to say, I admire the sense of adventure!