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So the camera is not actually 8k then?

F65 sensor 8k

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#1 Freya Black

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Posted 30 January 2013 - 03:17 PM

From the new Red Shark article about the Sony F65:

"The 20 megapixels quoted actually refer to the number of photosites on the sensor itself. Interpolation then allows us to increase the number of output pixels for 8K to 33 megapixels."

So it's not actually an 8k sensor, and it doesn't actually record in 8k, am I right in thinking that means the camera isn't actually 8k then? Dunno, I'm still trying to work out where the holes are in this "3perf" camera!

Sometimes I wish companies had more confidence in their products, theres certainly a fair percentage of the people who have shot on the F65 who have loved the images, can't the products stand for themselves? (Probably a very naive thing to be thinking but this kind of stuff does seem really silly)

Freya

Edited by Freya Black, 30 January 2013 - 03:17 PM.

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#2 Brian Drysdale

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Posted 30 January 2013 - 04:01 PM

Sony claim it to be true 4K, http://pro.sony.com/...shtml#/f65t1_1.

I expect this is a reaction to the 4k Bayer sensors, which don't have a 4k resolution when you measure it.
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#3 Freya Black

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Posted 30 January 2013 - 04:18 PM

Sony claim it to be true 4K, http://pro.sony.com/...shtml#/f65t1_1.


Yup that's the latest one. The 3perf thing was just for a while after it came out I think. Maybe someone realised it was really, really silly.

I expect this is a reaction to the 4k Bayer sensors, which don't have a 4k resolution when you measure it.


Well yes but now they are going to do something similar with the camera to allow it to record in "6k", I wonder what the 6k mode is then? Is that the "Fake 6k" mode if the 4k is true 4k? I suspect it won't be somehow!

This is all of course what they refer to as "Marketing".

I sometimes wonder tho, if confusing people is just as likely to put them off buying as make a sale? Dunno.

Edited by Freya Black, 30 January 2013 - 04:20 PM.

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#4 Victor Nhat Nguyen

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Posted 04 February 2013 - 05:10 PM

when are we going to stop chasing resolutions?
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#5 David Mullen ASC

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Posted 04 February 2013 - 05:54 PM

Because the Sony sensor is rotated 45 degrees there are actually 8K green photosites horizontally but overall 6K worth of total photosites... So Sony can definitely call this a "true" 4K image, otherwise they refer to the recorded file as 16-bit RAW, not "8K". Not sure that it matters now that it has more or less surpassed 35mm movie film resolution, which even though should ideally be scanned at 6K generally measures less than 4K even in ideal situations. Most charts I've seen hit closer to 3.5K if that, which is one reason why the 2.88K Arriraw file from an Alexa seems so close to matching 35mm resolution and in some situations looks sharper (knowing that "sharper" is a loaded word...)
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#6 Matthew W. Phillips

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Posted 04 February 2013 - 06:03 PM

Because the Sony sensor is rotated 45 degrees there are actually 8K green photosites horizontally but overall 6K worth of total photosites... So Sony can definitely call this a "true" 4K image, otherwise they refer to the recorded file as 16-bit RAW, not "8K". Not sure that it matters now that it has more or less surpassed 35mm movie film resolution, which even though should ideally be scanned at 6K generally measures less than 4K even in ideal situations. Most charts I've seen hit closer to 3.5K if that, which is one reason why the 2.88K Arriraw file from an Alexa seems so close to matching 35mm resolution and in some situations looks sharper (knowing that "sharper" is a loaded word...)


David, we have discussed this years ago and I have never followed up with you on this. What are your opinions of Spectra film and others that offer HD scans of Super 8? Do you believe they are, more or less, selling a fountain of youth, snake oil, etc? If not, how can you claim 35mm maxes out at 4k?
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#7 David Mullen ASC

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Posted 04 February 2013 - 06:29 PM

Because I've seen many line resolution charts photographed on 35mm color negative film and none that I've seen show 4K, they show slightly less than that. Someone show me a chart shot on 24mm wide piece of 35mm color negative (Super-35) that shows otherwise, please.

Doesn't mean that there aren't benefits to scanning at 4K if not 6K, you want the sampling rate to be higher than the original. For my own work I can see more detail with a 4K scan of 35mm over a 2K scan and there are plenty of examples that show that 35mm negative has more than 2K worth if detail and thus has more resolution than 1080P HD.

Just saw the ASC/PGA assessment tests, all finished and projected at 4K... And just judging by eye, Sony F65 was the most detailed followed by the Red Epic and then 35mm and the Alexa were tied for third.
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#8 Keith Walters

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Posted 05 February 2013 - 08:25 PM

I hesitate to put this old record on again, but what exactly do you mean by "4K"?
Do you mean, shooting a chart consisting of 2,048 black lines on a white background, that is, 2,048 white and 2,048 black vertical lines (or 2,048 line pairs).

OR do you mean the maximum number of lines it is possible to accurately resolve with a 4K scanner, that is 1,024 black lines on a white background, or 1,024 white and 1,024 black vertical lines (or 1,024 line pairs).

The only way you can make a "4K" display actually show 4,096 (or whatever) vertical lines is to get a computer to display a 4K wide bitmap (or GIF, PNG or some other "lossless" encoder). It is not possible to do that shooting a 4K test chart.*

JPEG, MPEG, and just about any other compression format will emphatically NOT put out 4,000 lines from a "4K" file. They will only ever put out a maximum of 2,000 lines. Same with 1920 x 1080, the maximum it can output is 960 vertical lines. The math in the decoder simply will not support any more!

*Edit for clarity: If you try to display anything above 2,048 vertical lines on a 4K display, what you actually will get is a mess of patches of 4K resolution fading in and out to grey.
By "patches of 4K resolution" I mean small areas, which, if extrapolated across the entire screen width would produce exactly 4096 vertical lines.
If you feed the display with exactly 4,096 lines, then yes, every other column of pixels will be either dark or light and you will get 4096 lines.

The question makes certain people get abusive and stop posting is as follows.

"OK, we've got an image consisting of 4096 vertical lines; 2048 at 25% brightness level, and 2048 at 100% brightness level, so every other line is 25% or 100%, giving a fine pattern on vertical lines.

"Now: What series of values would you apply to the lines to make it display 4094 lines?"
The answer is, there is no such series of values because the pixel columns can only ever have one brightness value across their widths. That is the little illuminated dots can't be light on one side and dark on the other!
The closest you can get to that situation is to have each line spread across two two dots, which means the maximum number of actual vertical lines a 4K display can faithfully display is 2048.

Here's where we run into the fundamental difference between film and a video camera. Fine-grain 35mm film is certainly capable of resolving more than 4,000 lines across its width, but you need a really good lens, stopped well down, and you also need to rack through the focus point as it's really hard to see that resolution in the viewfinder. The point is, film will be able to image 4096, 4095, 4094 etc lines all the way down to zero, with no aliasing or other artifacts.

In theory a 4K sensor might (just) be able to image a 4,096 line chart, but between there and 2048 lines would be just a mess of rubbish artifacts.


(I use the display analogy because it's easier to visualize, but exactly the same principles apply to image sensors).
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#9 Freya Black

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Posted 06 February 2013 - 06:57 AM

Because the Sony sensor is rotated 45 degrees there are actually 8K green photosites horizontally but overall 6K worth of total photosites...


Ah! Thankyou so much David! I was genuinely wondering where the whole 8k sensor thing originated from in the first place. I'm glad that it's not entirely just something made up in marketing.

I'm going to now ask what might have been a historically contentious question, that I'm hoping will be okay to ask these days, but is it 8k then in the same way that the red one was 4k? Or is this different? I understand that the F65 is using a non bayer pattern so it might be hard to make a comparison. Also if it has 8k horizontally as a result of this, does it suffer a corresponding loss in resolution vertically or how does it work?

Freya

Edited by Freya Black, 06 February 2013 - 06:58 AM.

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