Tech

Alexei’s articles about the technology of digital cinema.

HDx35 B4/PL Optical Adapter Test

July 29, 2012
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HDx35 optical adapter on the Arri ALEXA

ABOUT THIS TEST The HDx35 is an optical adapter that allows you to use B4 lenses, which were originally designed for the 2/3″ HD format, on a PL-Mount camera. The HDx35 is one of those products that looks really good on paper, and gets your creative juices flowing; “hey, I can get a 10x zoom on my ALEXA and stick it on my shoulder, and basically use it like an ENG camera. Or I get the equivalent of a 24-290 Optimo on my Alexa for a tiny fraction of the cost.” Hello, documentary shooting, here we come. I did this test to see how practical the adapter is to use in real-world situations, and what are the compromises and tradeoffs we face by putting another piece of glass between the lens and the camera…similarly, I wanted to get a feel for the adapter so I can decide whether or not to recommend it to my clients, and to find out what shooting situations would call for it. This test...

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Replacing Stolen 17″ MacBook Pro – Time For A Retina?

July 24, 2012
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Easy question: Which more painful? Losing your computer or losing your data? I’ll tell you what’s more painful than either: stupidly falling asleep with your front door wide open, waking up to find that you’ve been robbed. Now you’ve lost your computer and your dignity…for you suddenly realize, while walking around in your underwear chewing on a handful of almonds, that in spite of promising yourself to lock the door before going to bed, you not only forgot, but you closed your bedroom door and blasted the AC all night, sleeping the deep dreamless sleep of a real-life Homer Simpson. DOH! Luckily for me, a mere two days before this practically self-inflicted home robbery, during which the ballsy thief made off with my MacBook Pro and my Nikon D700, I realized that I needed to back up six month’s worth of work files sitting on my laptop. In the intervening week since it happened, I’ve managed to reconstruct most of what was lost, with a few paltry exceptions that will cost...

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Alexei’s Dream Camera

May 5, 2012
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the Arri Alexa seen beside the JVC falcon for comparative size.

I’m totally beyond excited – I’m the proud new owner of an Arri Alexa! I look forward to offering this excellent tool to my clients. This all started back in 2006 when I was on retainer with JVC as a “consultant.” I was an owner/operator of the then-exciting GY-HD101, the new generation of HDV cameras. Did a lot of shooting with that camera, a lot of which I’m quite proud of. At the time, Panavision and Sony had just come out with the Genesis (i.e. F35), Arri had the D20, Phantom had one high-speed camera, Dalsa was still making noise, and the RED 1 was still vaporware. It seemed obvious that Digital Cinema was around the corner. I gave a presentation to the head of sales China and the head engineer of JVC camera global, in which I proposed that JVC jump into the fray. I went ahead and designed a camera. Of course, not being an engineer, I couldn’t say exactly how the electronics would function, but I had some...

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To IR or not to IR?

April 11, 2012
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To IR or not to IR?

To IR or not to IR? The Arri ALEXA’s low-pass filter pack includes UV and IR-cutoff filters. According to Arri’s promo literature, you don’t need additional filters: The IR and UV cut-off filters let only those light frequencies reach the sensor which can be converted into a meaningful image. As with the D-21, the IR filter is specifically designed for the spectral response of the camera’s sensor, so no additional IR filter in front of the lens is required.(emphasis added) According to Arri’s FAQ (under “Exposure Questions / Can I use traditional ND filters with ALEXA?”), the story is a little different: While the close match between ALEXA’s custom designed IR filter and the sensor’s spectral response makes this issue less critical in contrast to some other digital camera’s, it is in general a good idea to only use traditional film ND filters up to an ND 0.9. So according to the promo materials Alexa doesn’t need IR-Cut ND filters. According to the FAQ however, you need ND/IR-Cut at...

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4k vs. 2k vs. HD (part 3 of 3)

April 3, 2012
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2K-vs-HD-vs-Super35-sm

More Art than Science There is more to watching a movie than being presented with a clear picture of fully-lit objects and people in perfect focus. The audience’s involvement in the story has to be more important than any of these technical considerations. I think there’s an audience psychology to consider. The film plays, and the story lives in the audience’s consciousness, sub-conscious and imagination. The audience participates in the film when they are left guessing. The audience is doing the “mental math” to connect the pieces together. For example: We see a shot of a man at his desk. We hear a noise of a glass breaking. The man looks up. Next shot: a closeup of a woman at the door, horrified. She looks down at something on the ground. Next shot:  the man gets up from his desk and approaches the camera. Next shot: a wider shot of the woman and someone walks into frame…but it is not the man we have seen at the desk, it...

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4k vs. 2k vs. HD (part 2 of 3)

April 3, 2012
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Is 2k Enough? Our eye is not the resolution king in the world of nature. Eagles have a much higher density of rods and cones in their eyes and can see details that are invisible to us. For an eagle, 2k looks like SD does to us; blurry. But our eye is very good with extremes of light and dark. Sensitive enough to read a book by moonlight, but hardy enough to pick out details in the edge of a cloud backlit by the sun. Our eye can see a contrast range of something like 20 photographic “stops.” That’s 20 doublings of light intensity, or a contrast ratio of 1,000,000:1. To our eye, contrast is more important than detail. I remember the first time I saw an image out of a RED ONE (pre-MX). I was stunned. It was displayed on two side-by-side 20″ Apple Cinema displays and the image went right off the edges of the screen. But what’s funny is that I’ve been in a lot of...

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4k vs. 2k vs. HD (part 1 of 3)

April 3, 2012
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4k vs. 2k vs. HD (part 1 of 3)

“Immersive” vs. “Involving” experiences. The 2k spec, for all intents and purposes, is 2048 x 1152, for a total of 2.36 million pixels. HD is 1920 x 1080, for a total of 2.07 million pixels. In other words, HD has 88% of the area (total pixels) that the 2k spec has. On a linear measurement, the difference is only 128 pixels…which only as big as that checkerboard over there. That edge-to-edge resolution difference between HD and 2k is only 6%, which most mortals can’t really see. The 2k spec comes from the digital scanners that scan a film negative from edge to edge. The reality is that Super 35 is, for example, “over-scanned” and the 2048-pixel width of the scan includes some material out of frame, like edge numbers and so on. The total image area of a 1.85:1  aspect ratio is closer to 1850 x 1000 pixels…or 1.85 million pixels total. So film scanned at 2k for digital intermediate results in an image somewhat less than HD, but...

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