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Focusing for 4K+ media , challenges to overcome

Les Dittert

Les Dittert

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I would like to open a discussion on the challenges of shooting actual 4K and higher resolution footage.
Let me preface this by defining what is meant by '4K' . For one, shooting on a camera with an adequate sensor, such as a Red, does not ensure you have 4K media in the end.
Factors include the obvious, such as good optics, but also camera movement ( both intentional and vibrations ). The operators ability to see the details are also worth investigating. Can you find focus with the LCD without going into zoom mode? Does the Canon mount auto focus pull accurate focus, even on a static shot ? How does one determine if your results are really 4K?

My personal interests are non narrative cultural shooting as a solo camera operator. Shots are often rushed as they are not staged and just happen, which is very challenging. And I want razor sharp results!

With the 6K sensor coming, I think the subject is ever more pertinent. I think it's worth discussing for possible solutions both hardware and firmware solutions.
 
Les, I think we want the same thing for different reasons. I have been heavily involved in marketing 4K projection. "Razor sharp" is exactly what I am looking for, but I am not seeing it very often. It seems most of the available footage falls short of being able to show off the capability of the 4K projector.

I think most of the best "4K" footage I have seen only achieves about 80-90% of the capability of 4K displays. I have wondered why I am disappointed in edge detail and texture. Why things just look soft. Why the footage isn't sharper. I want my projectors to look better, but the content is holding it back.

Is it a failure to focus? If so, it would seem to be overly consistent. You would think somebody would occasionally get crisp focus by accident. I am thinking there is a technology limit being reached in acquisition or finishing. Or finishing has to soften up the best to match the worst, for the sake of consistency.

If I examine nature like I look at projected images, I see a level of edge detail that appears to be what I am sure would be called by many purists "over enhanced." An "artifact" of nature. Maybe almost "ringing". This is especially true when you look at dark outlines against a bright white or light colored background. There is almost a faint lighter outline around the crisp edge of the dark object. Very high contrast. Look for it in a bright room. I pointed it out to a video processing expert recently. "Like [video] ringing" were his words. I can almost hear some of the video consultants whispering in our ears that we need to "turn down the sharpness control" on reality and then get used to seeing that way because it is "correct". I reject that. We have been taught that too much sharpness is "bad." I want more. Not more artifacts, just more real detail. At least to the point of what I can see in nature. (Then maybe just a little bit more, to transport me beyond reality.)

I like to call one aspect of it "fine detail contrast." The ability to resolve tiny black dots surrounded by white, without washing out the depth of the black dots. It appears to be necessary to resolve about at least a 4 micron dot pitch. At least with the size of current consumer projection display panels. Larger panels are probably more forgiving, but require a larger, more expensive optical path.

I think the latest in 4K video processing is able to help us get closer to the holy grail at the display side.

I too am interested in hearing more from the acquisition side about how to take this to the next level.

Rob McD.
 
Rob, I hear you.

Did you get a chance to see "Samsara" in a 4K theater a few months back? To me this films 4K image quality is the standard to measure other presentations by. Most of it was 'stunningly' sharp. It was shot on recent film stock, 65mm, scanned at 8k and down sampled to the 4k.
For me this is the goal, to get close to that quality when shooting with my RED. In the production extras on the bluray they essentially indicated that they chose 65mm because of the ultimate quality. I travel to India soon, with a compact camera package that will be a 30 lb backpack I will drag to all kinds of places, hopefully getting some interesting shots. The camera body they used on Samsara weighs more than my entire backpack/camera combo! I want to show that the Red can, with care and some modern processing, get to 'Samsara' levels of detail. But there are difficulties, so I started this thread to possibly explore them. This really is an engineering and science issue, and perhaps this forum isn't the best place to host it, I don't know. Nailing focus seems so basic, but with 4k it's not.
 
Funny you mentioned this, Les.

99.999% of underwater footage including all IMAX underwater footage ever shot does not resolve 4k even if "all the stars are perfectly aligned": the focus, lens alignment, water clarity, camera stability, etc... In fact, I have shown and scientifically quantified, that it is not possible to achieve even close to 4k quality using wide angle rectilinear lenses behind a dome or flat port underwater. Such underwater housings (all of the commercially available housings except ours) stuggle to achieve even standard definition quality around the edges.

So, here is one of the very first underwater footage frame grabs ever captured in the history of motion picture that actually resolves 4k: http://achtel.com/DeepX/A004_R003_1119WH.001930.jpg

In fact, this particular one resolves more than the Nyquist limit of 5k sensor that it was captured with....but I digress... :sneaky2:

Shot with submersible Nikonos 15mm at f/5.6. Please note the ultra-shallow DOF at 5k. Then re-size the image to 2k or HD and see how the DOF dramatically increases. Reduce it to 1k and everything is in sharp focus.

4k is a completely different ball game in terms of optics and critical focusing....the fact that something was shot on 5k camera or IMAX 70mm film deos not mean that it resolves even 2k...in many cases it doesn't. In cases of underwater images, it never did!

So, yes, the first is the sensor, then the optics and then the ability to focus the damn thing....I'm finally perfecting the last one :wink:
 
That's great Pawel, Congratulations!

It's fun pushing this camera as far as it can go isn't it?
With focus I'm finding that even a slight error will make it to 2K instead of 4K, without even noticing it on the small LCD. And I'm talking about static shots such as scenery, not complicated moving people.
 
I will have to check out Samsara, thanks. And I am very interested in what it takes to get digital cameras up to that level. And also more about what gets in the way.
 
yike!
Am just stepping up to HD focus from SD! Will watch this thread with interest.
thanks
Stu Aull
SX 199
(wPIX HD recorder)
Alaska
 
Just a laymen here, but I have noticed challenges getting sharp results from a Sony VPL-VW1000ES 4k projector in a home environment. In my case, the use of 4k material highlighted a projector lens that was slightly out of focus. Further, the texture of the screen (120") was apparent and it softened what should have been a sharp Windows 7 desktop interface.

Regarding optically resolving 4k images, my brother in law is a physicist and research scientist and does work with optics. When I talked about the 4k projector and showed him Timescapes, he mentioned that the size of the lens has a direct relationship on the ability to differentiate resolution. I guess that explains why the lens on the VW1000ES is so large compared to most "home" projectors.
 
Just a laymen here, but I have noticed challenges getting sharp results from a Sony VPL-VW1000ES 4k projector in a home environment
Click to expand...

Its a soft projector. One issue is LCOS, another is panel alignment, and another is quality of the lens. HD content looks really soft. I don't think the scaler is very good. Even the Sony cinema 4k projectors are soft when compared against the 4k DLP displays from Barco and Christie. 4k DLP chips for the home are still a couple of years per TIs roadmap.
 
as far as lenses and focus is concerned... the sensible thing to do would be deep dof to hit the sweet spot of sharpness and ease the pressure on focus distance. if that doesn't work out for your artistic goals, well - good luck.
 
Stacey Spears said:
Its a soft projector. One issue is LCOS, another is panel alignment, and another is quality of the lens. HD content looks really soft. I don't think the scaler is very good. Even the Sony cinema 4k projectors are soft when compared against the 4k DLP displays from Barco and Christie. 4k DLP chips for the home are still a couple of years per TIs roadmap.
Click to expand...

Stacey, I am surprised to hear your take on the 1000ES. I gotta disagree on just about every count from the many units I have worked with. 1000ES is most definitely not a soft projector. It's ability is what makes me know the demo content can get a lot better. Panel alignment adjustable down to 1/10th pixel. So no issue there at all. Sharpest home theater projector I have seen. It exposes softness, not causes it. Makes BDs look better than I've ever seen. Most HD projector lenses can only resolve 11 to 8 micron pixel pitch, this one can do 4 microns. That is on small (.74") home theater sized panels. Best lens Sony ever released to home theater. Size does matter. More sweet spot.

4K "reality creation" processing takes fine detail to a whole new level. Camera buffs that want to turn it off just have to see what it can do up close, then even the purists want to leave it on. Turn it off and it will be soft by comparison, though. Were your tests OFF or ON? I am guessing off.

Also, make sure test patterns are viewed in 3840 mode. 4x pixel count still looks better on patterns. 4096 scaling is fine for most video, with newer "non-static" processing, but H and V lines in mathematical patterns prefer 2x by 2x math better. Then the processing makes even the patterns look better. Normal mode keeps things in 4x. Zoom aspect modes use more pixels and more panel. That can fuzz patterns up quite a bit because they want to be mathematically clean.

I have seen one bad one. Definitely soft. There was something wrong with the lens. Hopefully it has been replaced, as I recommended.

Can't speak to the new 4K models from Barco and Christie. Haven't been involved in any of those shootouts.

Steve, I was a bit disappointed in the sharpness of Timescapes, too. Not bad, but not what I was looking for. I have definitely seen better, but mostly still looking and hoping. Also, the smoothness of 4K images on smaller screens often leaves screen texture, perfs, etc. exposed as the most obvious artifact.

Rob McD.
 
Rob,
On the Sony 1000ES, is that Panel alignment of 1/10 pixel a mechanical alignment or is that image warping to make the color planes overlap to that accuracy ?
If the later, it is softening the image a bit, as it has to interpolate positions.

My test on projectors is to display a pixel on - pixel off type of pattern and walk right up the the screen and see if I can see the pixels turned off and on. That's the test for actual native resolution. For example on DLP's I can turn off individual mirrors with such a pattern.

I have seen the white paper on the Sony upscale technology, and to put in bluntly, it is very sophisticated indeed. It is a form of super resolution that is trained with actual images, ala neural net type of technology. Nothing simple like a fancy multi tap resize algorithm.
 
Yeah, the newest levels of processing are getting very sophisticated, and are leaving a lot of the older "rules" behind.

The Sony pixel alignment leaves green alone, so the most visible brightness color pixel is untouched, but it is not mechanical, which would, if perfected across the screen, be even better. Red and Blue are brightness shifted between 2 pixels, so the best settings are at or near 10, 20, or 30, where a full pixel shift has occurred. 5, 15, and 25 are worst case, but still reduce the fringing nicely and I like the result better than without it. At 4k pixel size, missing correct focus, which is pretty easy to do, has much more effect on sharpness.

Another issue to watch out for when moving up in resolution:

This tends to affect those like me who focus pixels for a living. Visible sharp pixel edges in lower resolutions become a mental flag for "in focus." Which is true. When we see the pixel edges, that equates to "sharp." Then, when the pixels get 75% smaller, and less visible, the images suddenly look "softer" to our trained brain. But it may be just the loss of the pixel edge crutch.

This was true when moving from 720 to 1080, and now, though the pixels were less visible in 1080, they are much more nearly invisible in 4K. No more crutch. Gotta retrain the brain again.

Now the processing becomes much more important because we are losing sight of the technology and the image itself becomes dominant. Or, the actual level of detail captured in the shooting, to your thread's point.

Rob McD.
 
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uh... "soft focus = softness = 'filmic' = better" - alexa users.

duh ;)

seriously though, i feel like most often when i am blown away by footage from other red users it is always in sharp focus. even when shooting heavily stopped down for 3D, i find things can get soft very quickly at 4K if everything is not very carefully coordinated.

whatever happened to that red 'autofocus' feature that was teased a while back? i think the test shot was a '$ pimp chain' and a model (im serious, it was a '$ pimp chain') anybody else remember that?

daVinci Resolve is pretty amazing at tracking lines. the lytro camera is pretty damn cool. i feel like 'cinematic autofocus' is a reasonable enough goal to shoot for in the next few years. and obviously, if anyone is gonna do it, it's gonna be red.

this is seriously important though.. sharp focus is hard enough at 4K. dragon is coming within six months... in a couple years i'm sure our epics will be 9k. pulling focus at 9k (imax) will be a NIGHTMARE without help from some new tech.
 
Alec,
Glad to see the jist of the thread rekindled !

The LCD zoom 1:1 mode does help a bunch, and I don't know if it's my imagination, but I do think that the last beta firmware release made it somewhat faster to switch in and out of zoom mode. Having a small one to one pixel window in the middle of the viewfinder would be Nirvana for me, I could see the framing and the focus at the same time that way!
 
Les Dittert said:
Having a small one to one pixel window in the middle of the viewfinder would be Nirvana for me, I could see the framing and the focus at the same time that way!
Click to expand...

Yes, it would be great feature. Another one would be to be able to have one video path: HDMI, LCD or HD-SDI to show 1:1 for focus pulling while recording.
 
Les, I do a lot of solo shooting too, but usually have some help. I also do a lot of non-scripted shooting of the world around me. Lately I've been shooting Landscapes in the style of classic still landscape imagery, often stopping down and using Canon TS lenses. These shots are often up to 3 min long and intended to be looked at in detail or passively enjoyed just as you would enjoy wall art. Needless to say I am after fine detail and pristine 4K. Sharpe lenses and deep focus/smaller apertures are the first step. I've actually had good success with getting what I feel is good 4K out of Canon glass, but you have to be picky about the lenses and usually need to stop down to at least 5.6 ( I often go as small at T10) to get sharp landscapes with deep focus. I won't turn this into a lens thread but Canon has improved their lenses a lot with many of the newer Mk2 series lenses.
 
Mark,
I have a few Canon lens's and they work well when stopped down as well. Have you found the auto focus on the red to be just a little off ?
When wide open ( the easiest to focus with ) I find I can tweak it a little more to get optimum focus.
I would really like a DSLR style focus on RED , you know, open the aperture then focus then close aperture to taking position when done.
I have also suggested a fine-tune focus mode that wouldn't rack focus very much and usable even while rolling. A focus sweetener, so to speak.
They have a lot of irons in the fire and autofocus isn't really a professional cinema type of tool yet. So I understand.
 
How would people react if I released a software tool that tells you your footages actual resolution ?
Would it spoil the fun ?
 
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