8K DSLRs

[roxics]

8K cinema is 8192 x 4320 (1.85:1) or 35.4 megapixels. If you wanted to fit that into a 3:2 ratio 36x24mm sensor, what would the full resolution of that sensor be and what would the photosite size on that sensor be? Sorry I'm not good with figuring this kind of math out.

But it seems to me like that would be the optimal resolution for both video and stills on a single camera Enough resolution for stills shooters and pixel perfect no crop size for less moire when shooting video.

 

[combatentropy]

A 35.4MP 3:2 sensor is 7,290 x 4,860. Pixels are 4.9 µm.
An 8K 3:2 sensor is 8,192 x 5,461. Pixels are 4.4 µm.
An 8K 1.85:1 sensor with the same diagonal (43.26 mm), and so still uses the same lenses, is 38.06 × 20.57 mm. Pixels are 4.6 µm.
An 8K 16:9 sensor with the same diagonal is 37.7 × 21.21 mm. Pixels are 4.6 µm.

 

[Bruce Watson]

8K cinema is 8192 x 4320 (1.85:1) or 35.4 megapixels. If you wanted to fit that into a 3:2 ratio 36x24mm sensor, what would the full resolution of that sensor be and what would the photosite size on that sensor be? Sorry I'm not good with figuring this kind of math out.

But it seems to me like that would be the optimal resolution for both video and stills on a single camera Enough resolution for stills shooters and pixel perfect no crop size for less moire when shooting video.

Don't confuse megapixels with actual optical resolution. Academy ratio S35 3-perf film, shot in a good camera with excellent lenses, doesn't even reach the equivalent of 4K. You can scan the film at higher pixel counts, but it won't show any more actual optical resolution, because it didn't record any more. And S35 film is quite sufficient for huge theater displays. There's no point in going any higher. It's a waste of resources.

Even full frame 135 format film, drum scanned, will only yield the equivalent of 4K worth of optical resolution. I've drum scanned a lot of frames, and done the experiments. There's just not much there over 4K, except for the slowest and finest grained B&W, shot with excellent technique (tripod, mirror locked, cable shutter release, and lots of practice), which can get you to around 5K. There are no film / developer / camera / lens combinations known to man that will get you 8K worth of resolution from your 135 format film camera. You can't get around the laws of physics.

That, and there's a lot more to image quality than just resolution. And most of those other qualities can be improved by larger pixel sizes. All other things being equal, you'll likely get significantly better shadow detail and increased dynamic range from a larger sized pixel, for example. You'll also get better low light performance from bigger pixels.

So no. I'm not buying into the 8k idea. I'm not even buying into the "full frame" idea. I think videos and motion pictures look better with a smaller sensor. S35 hits the sweat spot and is an excellent sensor size for cinema cameras and lenses. Full frame 135 format is too big for video, and too small for stills IMHO.

 

[roxics]

Thank you so much for the replies guys. Sorry it's been so long. Honeslty i forgot about this thread.
The idea here is just to imagine a camera that can be useful to both stil shooters and cinema. I have no illusions it will be a perfect camera for either. It's just a thought experiment.

That said, I have a few more questions. If we took this sensor "An 8K 3:2 sensor is 8,192 x 5,461. Pixels are 4.4 µm." which means that for stills shooters you have a 3:2 ratio at 44.7 megapixels. Great for landscapes. You can then crop the top and the bottom to get a 1.85:1 area that is the full width of the sensor and complies with the 8192 x 4320 resolution of 8K cinema.

Now what happens:
1. If you crop a 1.5(3:2) area of the center of that sensor, how much resolution is that? - for APS-C stills shooters
2. If you crop a 1.77:1 ratio out of #1, what resolution do you get? - for video shooters
3. If you crop a super 35mm 4-perf area out of that native 8K sensor, how much resolution is that? - for cinema shooters (anamorphic use)
4. How much of a crop would there be to get a native 1920x1080 image out of this native 8K sensor?

 

[j1clark@ucsd.edu]

At this point, I bought the Blackmagic Pocket Cinema Camera, 1/2 price sale cinched the deal... but even at full price of $995... I choise 1920x1080(almost 2K...) and 10 bit Apple ProRes over the GH-4 which is listed as supporting 4K...

For me the biggest issue with 'under $5K' cameras is bit depth, heavy compression, and resulting artifacts.

As noted Film film gives a resolution upto about 3-4K with the 'best' of scanning... any more and all one is doing is scanning the remains of the silver glumps... aka grain.

That said, one can take a 4k image, 'add grain like' noise, and cover such digitizing artifacts related to the use of a raster based sensor, which lead to 'jaggies' or 'aliasing'...

 

[roxics]

I agree. Resolution isn't everything. This is just a thought experiment on building a sensor that can cover photography uses like lanscapes down to cinema uses.

 

[David W. Jones]

We don't even have 4K portable field monitors, let alone HD field monitors which are truly 1920x1080.

 

[Guest]

I am all for resolution improvements and options. 50megapixel video? delicious! But I feel like 4k is the best compromise of bandwidth to quality and practicability ratios. 8K+ for cinema, IMAX etc, but most practical purposes are fine with lower resolutions. I wouldn't mind an 8K standard, but 4k seems more practical all around. Everything from cellphones to TV's and computers could all theoretically have the same pixel density. Some people argue that HD is enough, but I think 4K is the minimum for TV and computer interface. I don't get bothered by pixels on a 4K screen. Thanks Sony/AMC for switching! It makes a difference!

 

[j1clark@ucsd.edu]

This sort of thing is sort of like...

Why can't my 35mm negative 'look' like a 8x10 camera negative...

The Wife use to shoot 2 1/4 x 2 1/4 negs for her weddings, always for the Formals, and some amount of candids... but by 2003 time frame, we had not used the Hasselblad for 2 years... shooting everything with our 'puny' 6M pixels...

One could these days buy a digital Hasselblad... but it is almost unnecessary for most 'wedding' work, even when someone wants a 'reasonable' enlargement...

 

[Guest]

This sort of thing is sort of like...

Why can't my 35mm negative 'look' like a 8x10 camera negative...

+1 36megapixels is that point on a 35mm format that just stops the craving for more resolution for me. Not that it needs to stop there though.

 

[roxics]

For the sake of this discussion, lets assume the sensor is a native bayer pattern 8k sensor (described above) that downsamples in-camera to a 4K 4:4:4 video file, while still maintaining it's full 8k resolution for stills. Just so we can skip past the "is 8K video even usefulness/practical" question that some might get hung up on. I'm more interested in knowing if it's possible to create a full frame DSLR that is capable of great video (without moire/aliasing isses) along with high enough resolution stills to satisfy landscape photographers who seek high resolution. All in one camera.

Obviously some (if not most) people would say that an APS-C size sensor is preferred for video/cinema. While that may be true from an objective cinema lens selection perspective, I think on the whole it's a subjective choice on the part of the shooter. Just like Christopher Nolan for example would prefer to shoot everything on IMAX sized negatives if he could and many flocked to the 5DmkII for its full frame look. So again, that's another discussion by itself.

Right now I'm curious what resolution this sensor would end up with, with a 1.5x APS-C crop and a 16:9 crop of that. Along with a 4-perf super 35mm crop of the native sensor and what resolution that would produce. Just math stuff I can't seem to figure out how to do on my own.

 

[Guest]

For the sake of this discussion, lets assume the sensor is a native bayer pattern 8k sensor (described above) that downsamples in-camera to a 4K 4:4:4 video file, while still maintaining it's full 8k resolution for stills. Just so we can skip past the "is 8K video even usefulness/practical" question that some might get hung up on. I'm more interested in knowing if it's possible to create a full frame DSLR that is capable of great video (without moire/aliasing isses) along with high enough resolution stills to satisfy landscape photographers who seek high resolution. All in one camera.

Obviously some (if not most) people would say that an APS-C size sensor is preferred for video/cinema. While that may be true from an objective cinema lens selection perspective, I think on the whole it's a subjective choice on the part of the shooter. Just like Christopher Nolan for example would prefer to shoot everything on IMAX sized negatives if he could and many flocked to the 5DmkII for its full frame look. So again, that's another discussion by itself.

Right now I'm curious what resolution this sensor would end up with, with a 1.5x APS-C crop and a 16:9 crop of that. Along with a 4-perf super 35mm crop of the native sensor and what resolution that would produce. Just math stuff I can't seem to figure out how to do on my own.

Could you rephrase the question?

 

[roxics]

Could you rephrase the question?

Ok. So we have a native 8K sensor. It's full frame, 3:2 ratio with a full resolution of 8,192 x 5,461.
When we crop that sensor to 1.85:1 we get 8192 x 4320 which is the cinema spec for 8K video.
So you're using the full width of the sensor, just not the full height when shooting video. Because you're shooting wider.

What I want to know are four things:
1. If you crop a 1.5x (3:2) area of the center of that sensor, how much resolution is that? A windowed mode, like some Nikon cameras can switch between FX to DX mode.
2. If you crop a 1.77:1 ratio out of that already cropped 1.5x area(like you would with and APS-C sensor when shooting video), what resolution do you get?
3. If you crop a super 35mm 4-perf area out of full sensor size, how much resolution is that?
4. How much of a crop would there be to get a native 1920x1080 image out of this native 8K sensor?

Basically the reason I want to know this is, I want to know how close to 4K we get when we crop a sensor like this for APS-C (3:2) and super 35mm (4:3) and what a 1920x1080 native crop size would be. Doe sit comes close to 16mm or something?

The idea being, could we build one camera with a full frame 8K sensor that can also be used in 4K mode at APS-C/Super 35 frame size and HD with 16mm or broadcast lenses and a deep DOF. I highly doubt that's the case, but I'd like to know the cropped resolutions just to see how close they come.

 

[Guest]

Ok. So we have a native 8K sensor. It's full frame, 3:2 ratio with a full resolution of 8,192 x 5,461.
When we crop that sensor to 1.85:1 we get 8192 x 4320 which is the cinema spec for 8K video.
So you're using the full width of the sensor, just not the full height when shooting video. Because you're shooting wider.

What I want to know are four things:
1. If you crop a 1.5x (3:2) area of the center of that sensor, how much resolution is that? A windowed mode, like some Nikon cameras can switch between FX to DX mode.
2. If you crop a 1.77:1 ratio out of that already cropped 1.5x area(like you would with and APS-C sensor when shooting video), what resolution do you get?
3. If you crop a super 35mm 4-perf area out of full sensor size, how much resolution is that?
4. How much of a crop would there be to get a native 1920x1080 image out of this native 8K sensor?

Basically the reason I want to know this is, I want to know how close to 4K we get when we crop a sensor like this for APS-C (3:2) and super 35mm (4:3) and what a 1920x1080 native crop size would be. Doe sit comes close to 16mm or something?

The idea being, could we build one camera with a full frame 8K sensor that can also be used in 4K mode at APS-C/Super 35 frame size and HD with 16mm or broadcast lenses and a deep DOF. I highly doubt that's the case, but I'd like to know the cropped resolutions just to see how close they come.

Ok, yes, that is a dream camera. Let's play. Will update in a bit if someone doesn't beat me to it, and I hope they do.

 

[Guest]

phfx_SensorChart2014 by onesielaff, on Flickr

for reference. this image was made by Phil Holland. you can learn more about him here: http://www.artbyphil.com/cgi-bin/phfx_news.cgi?display=new

 

[Guest]

s16 - 12.5mmx7.41mm

s35 3perf - 24.89x12mm

s35 4perf - 24.89x18.67mm

ff35 - 36x24mm


and for references:
65mm 5perf - 52.51x23.07mm

APS-H/Dragon 6k (my favorite for verite') ~ 28.7 x 19mm (Canon) and 30.7x15.8mm (Red)

70mm IMAX 15perf - 70.41x52.62mm

 

[Guest]

Of any of the formats you mentioned, s35 "3perf" 4k is the most widely used, so we should start there for the formula:

So, if we start with standard 4k cinema dimensions:
24.89X12mm = 4K

multiply by 1.5 to get 6K:
37.335x18 = 6K

and then double to height and width of the s35 format to get 8K:
49.78x24mm = 8K

and halve the height and width of the s35 format to get 2k:
12.445x6mm = 2k




All together again with reference to standard dimensions (color coded dashes to match graphic above):

resolution to ~1.85-1.9:1 format (standardized format size for reference)

-2K = 12.445 x 6 mm (s16 = 12.5 x 7.41 mm)

-4K = 24.89 X 12 mm (s35 = 24.89 x 12 mm)

-6K = 37.335 x 18 mm (ff35 = 36 x 24 mm)

-8K = 49.78 x 24 mm (65mm = 52.51 x 23.07 mm)


If we start with s35 3-perf 4K as a base, the other resolutions come very close to a standard format. Makes you wonder why no one is doing it.

So, we can see that the s35/4k and the s16/2k is close, but the 8k would end up being larger than ff35, and more like motion picture 65mm 5-perf. So, 6k would have to be your ff35 equivalent.

I know I answered your question backwards, but I figured this was your end goal: getting a camera that scales formats and resolutions as close to standards as possible, matching a standard resolution to the closest possible standard format all on one sensor.


Hope that helps, hope that makes sense.

 

[combatentropy]

So we have a native 8K sensor. It's full frame, 3:2 ratio with a full resolution of 8,192 x 5,461. . . .
1. If you crop a 1.5x (3:2) area of the center of that sensor, how much resolution is that? A windowed mode, like some Nikon cameras can switch between FX to DX mode.

5461 x 3640

2. If you crop a 1.77:1 ratio out of that already cropped 1.5x area(like you would with and APS-C sensor when shooting video), what resolution do you get?

5461 x 3094

3. If you crop a super 35mm 4-perf area out of full sensor size, how much resolution is that?

5652 x 4260 (4-perf)
5652 x 3167 (3-perf)

4. How much of a crop would there be to get a native 1920x1080 image out of this native 8K sensor?

4.55x crop factor

---

The math:

A 1.5x 3:2 crop would be 24 x 16 mm (compared to 36 x 24 for full frame).
Each side is exactly 2/3 (or 0.67 rounded to two decimal places) of the full-frame side:
24 / 36 = 0.67
16 / 24 = 0.67
So multiply each side of your original resolution by 0.67:
8192 x 0.67 = 5461
5461 x 0.67 = 3640

A 1.77 ratio crop from the already 1.5 crop would be 24 x 13.6. So the horizontal resolution, 5461, stays the same. But the vertical side is of course a little shorter:
13.6 / 16 = 0.85
3640 x 0.85 = 3094

4-perf Super 35 is 24.89 mm × 18.66 mm
24.89 / 36 = 0.69
0.69 x 8192 = 5652
18.66 / 24 = 0.78
0.78 x 5461 = 4260

But 3-perf is about what the RED, Alexa, and other "S35" cameras are. 3-perf is the one with the 1.52 crop factor. 4-perf's diagonal is 31.1mm, so its crop factor is 1.4.
3-perf Super 35 is 24.89 x 14 mm.
14 / 24 = 0.58
0.58 x 5461 = 3167

Native 1920 x 1080:
1920 / 8192 = 0.23
1080 / 5461 = 0.20
36 x 0.23 = 8.28 mm
24 x 0.20 = 4.8mm
So the rectangle would be 8.28 x 4.8, and the diagonal would be about 9.5.
So the crop is 4.55. (43.26 is the diagonal of full frame. 43.26 / 9.5 = 4.55)
This is a little smaller than the 16:9 2/3" optical format, which is 9.6 x 5.4, or 11 mm diagonally, and whose crop is 3.93.

 

[combatentropy]

A more realistic way to reach what I think you're after is an S35 chip and a Micro Four Thirds mount, like the JVC GY-L300.

With a Micro Four Thirds mount, not only could you adapt it to almost any lens, but a SpeedBooster could bump it up to full frame. A SpeedBooster's crop factor is 0.7. This would make an S35 sensor have a FF35 angle of view (1.5 x 0.7 = 1.05).

As for resolution, if the chip is natively 5.2K, then it could be adapted to any format down to 2/3 with resolution that is at least acceptable:

Lens	Res	Mount
FF (135)	5.2K	speedbooster
S35	5.2K	adapter or native m43 (you can get lenses with m43 mounts that cover S35 or even full frame)
4/3	4.0K	adapter or native m43
S16	2.7K	adapter or native m43
16mm	2.3K	adapter or native m43
2/3	2.0K	adapter or native m43

A 5.2K sensor is realistic. The Canon 7D, for example, is S35 and 5.2K. It's also about 15 megapixels, for the still photographers out there.

(Since the JVC is "just" 4.5K, its resolution for the 2/3 format will be just 1.7K. Wah. But 16mm will be a tad over HD (1.99K).)

So: 5.2K, S35, m43.

(I said the same thing in this post in another thread. Although, actually I am not a resolution junkie and would be fine with even a 2K S35 m43. 2K looks just dandy, as the BMPCC has demonstrated. Not wanting to get into an argument, though.)

 

[Guest]

@combatentropy

One would presumably want at least one standard format combination, like 4K s35, rather than having to rescale every format in post (oh we have done it, opened pandora's box again )