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By Marco Tecno · Posted
These shots are very nice (and those guys look absolutely groovy) -
By HockeyFan12 · Posted
You'd think so. So did I. But we're dealing with more complicated systems than "divide by two." Frequency in the Nyquist-relevant sense is a sine wave. With sound, the appearance and sound of a lone fundamental sine wave are well-known to anyone with a background in subtractive synthesis. In terms of images, however, we usually think in square waves. Compare the images I posted of a sinusoidal zone plate and a standard square wave plate. Resolution charts generally represent square waves, which contain infinite higher order harmonics and thus are theoretically of infinitely high frequency at any given high contrast edge. In theory, a square wave resolution chart is liable to alias at any given frequency, and in practice it might alias at low fundamental frequencies if the contrast is great enough (see Yedlin's windows on the F55). Yes, the higher the acquisition resolution the less aliasing there is in general, but the "oversample by two" dictum works so well more because it lets the B and R in the Bayer grid reach full resolution than because it fulfills the specific terms of the Nyquist theorem in a monochrome sense. As you correctly state, 4k pixels can represent a maximum of 2k line pairs: one black pixel and one white pixel per line pair. But 2k line pairs times two lines per pair equals 4k lines. And I think we can agree that one black pixel and one white pixel are two distinct pixels... so 4k linear pixels can represent 4k linear pixels... which still only represents 2k cycles (line pairs). Nyquist holds true. And in practice, a 4k monochrome sensor can indeed capture up to 4k resolution with no aliasing... of a sinusoidal zone plate. When you turn that zone plate into square waves (black and white lines rather than gradients) you can induce aliasing sooner because you're introducing higher order harmonics. NOT because the fundamental is surpassing the 2k cycle threshold. Again, 4k image resolution measures pixels. 2k line pairs measures pairs of pixels. Nyquist holds true. But the reasons why you see aliasing on those test charts with the C300 Mk II and not the F65 are not because Nyquist demands you oversample by two (it's really more like Nyquist converts pixel pairs to signal cycles), but because those test charts' lines represent infinite order harmonics and that oversampling in general helps prevent aliasing at increasingly high frequencies. As predicted by math and science. -
Some of you may interested, i tested my Feiyu MG V2 gimbal with my 5D Mark II + 24-105 F4 L The max payload for the gimbal is 1630g, the camera + lens is 1520, and it worked perfectly. I i didn't even tuned to motors yet. I used ML RAW with 1856x928 at 23,976 fps. The focus was fixed (the AF is terrible with live view on the 5D2) The gimbal was calibrated with the lens set to 35mm. After that at the 24/50/70/105mm there was no recalibration the motors handled perfectly the unbalanced setup. Colorgraded in Davinci Resolve with Cinelog and Ektar 100 Advanced LUT from hyalinejim 5D2 on Feiyu MG V2 gimbal
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Balloon juice? Do you mean debunking folks hoaxing UFOs with balloons or something political? If the later, do your own research and be prepared to accept what may at first appear to be unacceptable- ask yourself why you are rejecting it when all the facts show otherwise. You will be truly free when you accept the truth, more so when you start thinking about how to help repair the damage that has been done and help heal the world. Regarding generative compression and what will someday be possible: have you ever studied DNA? Would you agree that it's the most efficient mechanism of information storage ever discovered in the history of man? Human DNA can be completely stored in around 1.5 Gigabytes, small enough to fit on a thumb drive (6×10^9 base pairs/diploid genome x 1 byte/4 base pairs = 1.5×10^9 bytes or 1.5 Gbytes). 1.5 Gbytes of information accurately reconstructs through generative decompression, 150 Zettabytes (10^21)! (1.5 Gbytes x 100 trillion cells = 150 trillion Gbytes or 150×10^12 x 10^9 bytes = 150 Zettabytes (10^21)). These are ballpark estimates, however the compression ratio is mind-boggling. DNA isn't just encoding an image, or a movie, it encodes a living, organic being. More info here. Using machine learning which is based on the neural networks of our brains (functioning similar to N-dimensional gradient-descent optimization methods), it will someday be possible to get far greater compression ratios than the state of the art today. Sounds unbelievable? Have you studied fractals? What do you think we could generate from this simple equation: Z(n+1) = Z(n)^2 + C, where Z is a complex number? Or written another way Znext = Znow*Znow + C? How about this: From a simple multiply and add, with one variable and one constant, we can generate the Mandelbrot set. If your mind is not blown from this single image from that simple equation, it gets better: it can be iterated and animated to create video: And of course, 3D (Mandelbulb 3D is free): Today we are just learning to create more useful generative systems using machine learning, for example efficient compression of stills and in the future video. We can see how much information is encoded in Z^2 + C, and in nature with 1.5Gbytes of data for DNA encoding a complete human being (150 ZettaBytes), so somewhere in between we'll have very efficient still image and video compression. Progress is made as our understanding evolves, likely through advanced artificial intelligence, to allow us to apply these forms of compression and reconstruction to specific patterns (stills and moving images) and at the limit, complete understanding of DNA encoding for known lifeforms, and beyond! -
By Nicholson Ruiz · Posted
@MountneerMan last weekend I was shooting outside. At times it would be cloudy and other times the sun would show it's face. I was trying to lock my iso, shutter speed etc. when it was cloudy so that the sun doesn't affect my image. I was shooting in manual mode but couldn't lock my settings using the AEL button. I even changed it in Key Mapping option. After messing with the camera after my shoot, I've discovered you can lock exposure in Aperture Priority but you cannot changed the shutter speed. Thanks for the reply. @BopBill and @IKSLIM thanks also for the reply.
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