moonlit

We were pretty excited to see how the Sony A7S would perform when it was announced last spring during the NAB trade show. The A7S had tons more processing power, could handle 4K video capture and had an ISO range of 50-409,600—putting it on-par with the Nikon D4s.

This video, released last week by Carbon Studios, puts the sensitivity of the A7S to the test and shows that the camera performs great in incredibly low light situations. The moonlit video was captured on Sept. 8 from 12:30 a.m.- 2 a.m. The first scene was shot at 1/25, f/1.4 with a 25,600 ISO; the second shot at 1/25, f/1.4 with a 32,000 ISO and the rest of the footage at 1/30, f/1.4 with a 12,800 ISO.

We can’t wait to put the Sony A7S through a full Pop Photo test.

The post Video: Sony A7S Moonlight ISO Test appeared first on Popular Photography.

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Say you’re tuning a radio to a station with a weak signal. You turn up the volume and hear static. Why? By amplifying the signal, you’re also amplifying unwanted stray electronic bits: audio noise.

Electronic noise in digital photos has the same cause: Amplify a weak signal from an imaging sensor too much, and you also amplify stray electrons in the sensor or elsewhere in the circuitry. It shows up in your pictures as coarse grain (sometimes okay) or color mottling (often pretty ugly).

A digital sensor is basically an array of tiny light meters, called pixels. Each pixel reads the light level at its spot on the sensor, and this measurement is bundled with those from the other pixels to make a picture file. (We’re skipping several steps for simplicity.) But if the tiny meters get too little light, the signal they send will be too weak unless—yep—you amplify the signal. And by doing that, you turn up the volume on the noise.

The volume dial on your digital camera is the ISO setting. Crank up the ISO, and you can shoot in less light—at a cost. Most DSLRs now have acceptable noise levels up to ISO 3200. Compacts do not.

Like radio receivers, some sensors are better at producing a clear signal. The major issue is pixel size. If you think of a pixel as a light bucket, a bigger pixel gathers more light than a smaller one. Which means you need less amplification of the signal. Which means the good signal will be proportionally much greater than the noise (called the signal-to-noise ratio).

DSLR sensors, with much greater area than compacts, can fit bigger pixels. Example: The Nikon D3S’s 12MP full-frame sensor employs comparatively huge 8.45-micron pixels (0.00845mm), while a 12MP pocket camera will have pixels of about 1.5 micron.

Other factors can influence noise and there are some effective strategies for reducing it. But there’s still no substitute for big pixels.

The post How To: Understand Noise appeared first on Popular Photography.

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Andrew Schär put together this demonstration after reading a document calling for the use of ISOs that are multiples of 160 when shooting video with his Canon DSLR, which prompted him to test just how much the simulated ISOs in between full steps make a difference. Using his Canon 60D, he recorded a full range of ISOs, and found something that’s pretty different to the assumed proportional relationship between ISO number and noise levels. His test showed that ISOs that were multiples of ISO 160 (160, 320, 640) were far and away the best, then the multiples of 100, and the multiples of 125 were muchworse.

Try it on your DSLR.

Testing Canon’s ISO noise in Video mode on the 60D from Andrew Schär on Vimeo.

One possible explanation is to do with which of these ISOs is native, and which simulated. Normally, the multiples of 100 are the standard ones, and to get the in between numbers you have to either increase or decrease the gain. Martin Zahuta commented on the original test, and summarized it well:

Similarly, when set at ISO 160, the camera actually already goes for ISO 200 and applies NEGATIVE GAIN, making the image darker and thus hiding a lot of the noise.

[Wiegärtner Films, via Giz]

The post The Best ISOs For Shooting Video Come In Multiples Of 160 appeared first on Popular Photography.

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