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    Senior Member James0b57's Avatar
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    Quote Originally Posted by Joshua Cadmium View Post
    The chart is absolutely NOT for the 12K sensor - it's just an example of how a random lens performs on a random sensor. The numbers don't matter, just that there is always a point in the system where resolution is maximized and an f stop range where target resolution can be achieved.

    You could technically make a chart like that for the 12K sensor, but you would have to make one for every lens you use on it and it would not tell you anything about what the lens is actually doing to the image, except regarding pure resolution.

    In the words of Carl Sagan: "extraordinary claims require extraordinary evidence." Most of what I am posting is counter-intuitive, so I am trying to draw from whatever I can to prove my point.
    Oh, I was just curios about the chart specifically, because it mentions "4K" resolution, but that statement today is oddly nebulous. Getting a 4K from a bayer sensor that is just over 4 thousand pixels wide is technically "4K", but once it is processed to a full colour image, it invariably resolves more similar to HD. Wheres if a 4K image is derived from a 5.7K or 6K sensor, it can actually resolve a 4K image once processed.


    While, in my work, I don't obsess about resolution after 4K raw, I still do recognize that a 4K raw camera and a 6K raw camera would have different tolerances for lens "perfection".


    Idk, was just looking for a more anecdotal interpretation of that chart, since it is never really clear what the actual resolution of "4K" is when talking about the camera side of things. A TV generally will have around 4 thousand pixels, but cameras can just have 4 thousand photo sites and still be called 4K.


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    Quote Originally Posted by James0b57 View Post
    Idk, was just looking for a more anecdotal interpretation of that chart, since it is never really clear what the actual resolution of "4K" is when talking about the camera side of things.
    Well, that goes back to what you define as resolution.

    If you can capture 3840x2160 worth of pixels or 8.3 megapixels, you could call that 4K. Netflix basically would.

    Does a 4K Bayer pattern sensor actually capture 3840 lines or 1920 line pairs? No. It's going to do somewhere around 80% luma resolution and less than that on chroma resolution. That's why there's the whole 5K for 4K idea. That gives you about 100% luma, but still less chroma resolution. As you move up to higher Ks, you will get more chroma resolution and the extra luma resolution will downsample better and the fidelity of the image will look better.

    Then, on top of that, with a lens, you need to make sure that you are hitting that 4K target window if you actually want to image 4K worth of resolution. So you need to make sure - either from stopping down or avoiding too much diffraction, that you stay in that f stop range that actually gives you 4K worth of Airy Disks. Even if you are in a 5K or higher sensor resolution, you could still target that 4K because shooting at a higher resolution is just to counteract the limitations of the Bayer pattern and because while about 80% is luma resolution, the other 20% is false information that you could blur away with limited penalty.

    Despite everything I am saying, I definitely think this f stop window I am talking about matters much less, because I like how certain lens aberrations look - especially on anamorphic - and sometimes you want a softer, dreamier, romantic feel - or it is just such a slight difference that capturing slightly less than 4K Airy Disk just practically doesn't matter to what you are shooting. I mean, except for limited circumstances, no one is practically going to care if you aren't technically funneling 4K worth of Airy Disks into the sensor, if the image looks great and it meets certain basic resolution criteria (like just capturing 4K worth of sensor pixels).

    It's not like clients or Netflix is saying - hey, before every scene we need you to focus on a resolution chart to make absolutely sure 4K worth of resolution is properly imaged. But, I think it is helpful to know all this, in order to avoid going into a loss of sharpness that IS perceptual - the image doesn't look great - especially (and once again) if you are punching in or capturing a smaller slice of the image.


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    Also, as mentioned earlier in this thread, just because a sensor has a defined photsite count, doesn’t mean the size of those site are necessarily the same between another camera with the same resolution, meaning diffraction between two sensors of the same resolution may translate differently.

    But yes, none of this is particularly going to matter for an artist telling a story. Though, i still enjoy talking about it. Was trying to just get a more general idea what kind of theoretical “4K” resolution that chart was getting at. But no matter, not trying to make it a big deal or some absolute rule. Just chatting. ...but i suppose this discussion is destroying cinema. haha

    To be honest, i don’t think anyone is overthinking this, so much as exploring the concepts. It is much like the 2K vs 4K debate. At a certain point it doesn’t matter. The Mini LF looks amazing. The resolution isn’t the only variable i. Good or bad image capture. Also, i’ve seen novices with a good eye shoot better than old veterans of the trade.

    Dvxuser has long been no stranger to overly technical conversations, and it is a part of this forum that i’ve always enjoyed. Even if i know some of it won’t change my day to day, i’m still interested in how the tech is made. There is something enriching to understanding the physics of not just the cameras, but also the world around us, and that shapes our world view.... which ultimately effects how we think and create art.

    If we want to dumb things down to sell cameras, we’d all be on reduser.
    Last edited by James0b57; 10-26-2020 at 02:29 PM.


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