4K 16X9 scaled (zoomed) 400%?

[Alan Calzatti]

How much can I scale (zoom) 4K 16X9 footage for a 1080p project? is 400% to soft? it's for a DVD only release.

 

[Jannard]

How much can I scale (zoom) 4K 16X9 footage for a 1080p project? is 400% to soft? it's for a DVD only release.

Let me see... you want to crop in 400% from Quad HD? Is that right? If so, that nets you about 720p-ish. Not sure why you would want to do that with this camera... how about some more info?

Jim

 

[Alan Calzatti]

I want to have the option to zoom in my footage or punch in. I only have 2 Reds on my project, so I'm looking into alternative options.

 

[Gary Stone]

I wouldn't want to rely on post for framing.

 

[Alan Calzatti]

has nothing to do with framing. Just a thought to maximize my footage. I'm working with an artist in iceland who refuses to do more then 2 takes for a song. I wanted
to run my footage a couple of times through redcine, with a few focal length options.

any thoughts?

 

[Alex Boothby]

....for a 1080p project? .... it's for a DVD only release.

Sorry, SD or 1080p finish? That makes all the difference.

 

[Alan Calzatti]

It will be finished in SD

 

[Mark Mannschreck]

over about 200 goes too soft even on the sharpest lenses (with focus nailed) - and that's even for SD... you can go further with some sharpening. For quick cuts in a music video you may be able to get away with more

 

[Alan Calzatti]

Thanks for the info. I'll try to run a test tomorrow.

 

[Alex Boothby]

SD 16x9 letterbox (720 x 405) ...?

Theoretically (with quality lenses) you should be covered for a 426% blowup

4096 x 0.75 (reasonable debayer loss) / 720 = 4.266

Don't forget to focus! And don't underexpose.

 

[Alan Calzatti]

Thanks Alex!

 

[Alex Boothby]

Then again in practice I've never done more than a 3x blowup for an SD finish - under the absolute best of circumstances (master primes, fat exposure, noise reduction, etc).

For more info see Greame's discourse on distilling whiskey.

 

[Alan Calzatti]

Thanks Alex

 

[Pietro Impagliazzo]

How about running both cameras with zooms and alternating between focal lengths when one is on wide put the other one on someone's CU, rehearse (if possible) or get the operators to understand exactly what's gonna happen. Are you gonna use focus pullers on both cameras?

If everything goes right you won't need a blowup as big as 400% or won't even need to blowup at all.

 

[D Fuller]

I'm a little more optimistic on the cropping possibilities...

I'm a little more optimistic on the cropping possibilities...

I did a spot earlier this year that, for technical reasons related to the creative, relied on a significant crop. The crop (blow-up, as the editorial house kept calling it) was more than a 400% change in scale. The spot was finished in SD, and was shot in 4K HD on build 17. We used Zeiss Master Primes, because we knew we would be testing the limits of resolution, but it worked very well.

The frames here are from the ungraded footage, but they approximate the crop done in the spot.

This first frame is from the first shot in the spot, and is a crop from a shot framed identically to the one below it, which is the last shot in the spot. In After Effects, the first frame is a reduction of the R3D to 75%; the last frame is a reduction to 23.4%.

It took a lot of convincing to get the post house to go forward with this idea, but in the end, everyone (client, agency, editor, me) was very happy with the result.

 

[Alex Boothby]

Thank you David for these examples. A few comments:

It is easy to measure pixel ratios, theoretical debayer loss and even the MTF of a given lens. What is harder to calculate and therefore predict is the amount of stress you will put on an image in post. Every time you color grade an image you push pixels away from their native values. A high-con color grade will exaggerate noise in the image, stabilization and repos will soften an image, and chroma keys and difference keys will strongly react to the slightest flaw.

David's example above is perhaps the PERFECT demonstration of an successful blowup under truly ideal circumstances; master prime lens, perfect focus, a low(ish) dynamic range scene with bright subject and environment, exposure to the right (I'm guessing) and a flat final color grade that is somewhat close to the native raw image. These results would likely be far less perfect had David underexposed a stop or two, missed critical focus, or stressed the image in post with a more radical grade.

As an analogy, it is reported that a 4K scan of 35mm film yields 3.2K in measured pixel resolution (a figure I believe). Knowing this, we could therefore argue that super-8mm film would be sufficient for a SD finish!!! Of course this is never done simply because the image would fall apart in post under the slightest stress. Likewise 35mm to SD is much more robust than super 16mm to SD. That's a pretty simple concept and the same holds true for Red, whether the issue is extreme blowups or shooting 2K slow mo.

I believe that post manipulation is the true wild card when assessing a complete imaging system. It is basically impossible to measure and is an area subject to dramatic change at the last minute (regardless of prep). For this reason I advise caution when considering extreme blowups and the like.

 

[PatC]

Really helpful example Fuller. Great post. I totally buy it.

 

[Alan Calzatti]

Thank you David for the example and the information!