You’ve probably heard of cameras that can detect wavelengths of light that human eyes can’t, and also cameras that can detect heat in a scene, but have you ever heard of one that can capture sound? That’s right: scientists at the Korea Advanced Institute of Science and Technology have created a portable sound camera that’s sensitive to sound waves.
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Photographer Zack Arias created this video titled Signal vs. Noise to help his fellow photogs refocus their lives and careers. His advice: “Look for the signal in your life, and not the noise.” Arias writes,
As 2012 was coming to an end [...] I felt as though my brain was full. There wasn’t any more room in it. I can’t take any more information. My head was filled with noise and trying to find anything of any substance was difficult. I would do my best to remember what I was going to the store to buy, but when I walked in the door I couldn’t remember. I’d sit in meetings with my studio manager where she would ask about the direction for the new year and I’d draw a blank. “I don’t know.” My mind was filled with thoughts but I couldn’t string them together in a coherent way to save my life.
Each year I take the month of December off from social media. I like to disappear, go work on stuff, and come back feeling fresh. Nearing the end of 2012 I knew I needed to leave all of that behind sooner than December and most likely stay off of it until the spring. My mind was stuck on static and the volume was set to eleven.
Arias has developed a number of strategies for strengthening signal and killing noise. Head on over to Scott Kelby’s blog for the whole shebang.
It’s Guest Blog Wednesday featuring Zack Arias! [Scott Kelby's Photoshop Insider]
Astrophotography enthusiast Don Marcotte wanted to find out whether the Canon 6D or Canon 5D Mark III was more suitable for his area of photography, so he pitted the two cameras against one another in a few noise tests at his local camera store. He simply shot long exposures without any light (the cap was on) in order to see how much noise would show up in the frame.
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Canon made a splash earlier this month by announcing its first EF pancake lens, the Canon 40mm f/2.8 STM. If you’re considering this lens, one thing you should know is that the autofocus noise may interfere with your videos unless you use an external mic. In his review of the lens, photographer Dan Carr writes,
Here then is probably the biggest problem with this lens. With any other Canon lens, if you think the AF motor is making too much noise you can either switch to manual focus mode to disengage the focus motors or with Canons l-series lenses and their ultrasonic motors you simply just turn the focus ring manually yourself and it doesn’t engage the noise producing AF motor. Unfortunately though, the STM motor works in a different way [...] Even when you switch to manual focus mode, rotating the the focus ring engages the STM motor to move the lens elements as the whole thing is a focus by wire system. This means that there is absolutely no way for you to get a silent video. Whether you let the camera do the focusing, as with the new cameras like the 650D/T4i , or whether you do it yourself, you are going to get the background hum as demonstrated in my video
It’s an interesting quirk, since the STM technology is meant to provide smooth and quiet focus for video recording. It may be quiet (here’s a comparison with the 50mm f/1.8 II), but you can’t eliminate it completely. On the flip side, the lens is attracting rave reviews.
(via Dan Carr via Foto Actualidad)
The first sample images of the Nikon D3200 have just come out of Nikon France; and although they look great for the most part, the one low-light image confirms suspicions that Nikon may have gone too far putting 24.2-megapixels in the camera. More noticeable on the full-resolution photographs, you can tell that once the ISO is cranked up to about 1600, noise begins to play a significant role. Read more…
Japanese website mono-logue released this short 30-second video comparing footage from the Canon 5D Mark II and the new 5D Mark III captured at ISO 12,800. The difference in noise levels is remarkable (be sure to watch it full screen and in HD).
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If you’re a fan of learning things through Khan Academy, then you might enjoy learning about how ISO works in this similar-styled tutorial by Dylan Bennett. Bennett might not have Salman Khan’s soothing voice, but he does his best to break down the magic of digital camera sensors into easy to understand ideas. For a more detailed and comprehensive understanding of how things work, check out Cambridge in Colour’s excellent tutorials.
Want to see how far DSLRs have come in the past decade? Lee Morris of Fstoppers published these two photos taken at Super Bowl halftime shows. The crop on the left was captured in 2001, possibly with the Nikon D1H at 2.7 megapixels and ISO 800 (state of the art specs at the time). The slice on the right was from this past weekend, and was shot with a Nikon D3s at 12MP and ISO 12,800.
Image credits: Photographs by Lonny Krasnow/AP and FilmMagic
Last Friday an anonymous poster on the photography board of 4chan sparked a discussion that rippled into the blogosphere after freezing their camera to see whether ISO performance improves at lower temperatures.
They stuck their Sony A350 into the freezer for 15 minutes, and posted the following before and after comparison of noise at ISO 3200:
Regardless of whether or not these results were fabricated, it has long been (though perhaps not widely) known among photographers that digital cameras have better ISO performance (i.e. less noise) at lower temperatures, which is why sensors are often cooled for astro-photography. Other photographers also report improved ISO performance when shooting in very cold environments.
Zodiac Light did an interesting experiment in which a Canon 350D was cooled, and the amount of noise measured. They found that cooling the sensor resulted in a 40% drop in the amount of noise.
Obviously you shouldn’t freeze your nice camera to test this out yourself, but it’s an interesting fact to know, and could be useful if you’re interested in long exposure photography.
(via The Phoblographer)
Thanks to Nathan Yan for briefing us on thermal noise.
Image credit: Don’t drop your camera! by Island-Life and used with permission.
Something you may have noticed when adjusting your camera’s ISO setting is that as you increase ISO, the number of remaining shots you have decreases. This is because the size of each photograph increases with ISO, and thus less of them can be stored in the available space of your memory card.
So why does the file size increase as you increase ISO? The answer has to do with image noise and file compression. First we’ll discuss the noise element.
You probably know already that a higher ISO number leads to more noise in the resulting image. This is because digital cameras achieve the same behavior of “more sensitive film” by amplifying the image signal the camera receives when it captures a photograph. This amplification also amplifies the noise that exists in every image regardless of ISO, and therefore higher ISOs have highly amplified noise.
To demonstrate, I captured the following photograph at both ISO 100 and ISO 3200:
Here’s a side by side comparison of crops from the two images:
The noise should be pretty obvious. The RAW file of the ISO100 version is 10.2MB in size, while the ISO3200 version is 14.7MB. In this case, the higher ISO leads to a 44% larger file.
An interesting property of digital cameras is that there is more noise in darker regions of photographs than brighter regions. The opposite is true for film. This means that the file size difference discussed here will be far less when shooting with more light, such as when you’re photographing outdoors.
As an example, here is another scene that I photographed first at ISO100, and then at ISO3200:
Though there is still a significant amount of noise in the image, the ISO100 photo has a 15.8MB file size, while the ISO3200 photo is 16.7MB. This means that for this outdoors shot, the higher ISO only caused a 5.7% increase in file size. There’s other factors that will cause this percentage to fluctuate, such as the complexity of the scene, but in general the percentage should be less when photographing with more light.
Now that we’ve shown the increased image noise that comes with higher ISO numbers, we’ll discuss why this causes the file size to increase.
Regardless of whether you’re shooting RAW or JPEG, it’s likely your photographs are stored in a compressed format. While some cameras allow you to choose whether and how files are compressed, RAW images (i.e. Canon’s CR2 format) are usually compressed using a lossless algorithm, meaning the exact original data can be reconstructed from the compressed data. On the other hand, JPEG is lossy, so the more you work with JPEG files, the less data you’ll have as the compression throws out more and more data.
Here is a sequence of images from Wikipedia showing lossy compression (with PNGs):
The image on the right is the most compressed, and therefore has the least information. There is no way to recover the original detail from the compressed image to reconstruct the original (on the left), since the information was thrown out in order to save space when compressing the file.
The reason noise increases file sizes is because image compression relies on repetition, or patterns. In images with less noise, there are more areas of consistent patterns (i.e. the clear blue sky) that can be compressed. On the other hand, when noise is introduced, these adjacent areas that could have been grouped together and compressed must be split and stored separately, since the noise introduces randomness that cannot be compressed.
Here are four different 100×100 JPEG squares, saved with the same image quality:
On the left is a square with solid blue, which affords maximum compression and therefore the smallest file size. The second square has two shades of blue, alternating by row, while the third square alternates by column. Due to the way the JPEG format compresses images, the second square can be compressed more efficiently than the third, even though both contain exactly the same number of pixels of each shade. Finally, the last square has artificial noise added in using Photoshop. This noise introduces randomness, which results in the least compression and the largest file size.
Now, for a super simplified example of compression, consider the following “photo” with 3 “pixels”:
Since all three pixels are the same, instead of storing the data for all three, one possible way I could “compress” the photo would be to store the color information once and just remember that the entire range of pixels is that color. (i.e. Pixel 1-3 = Blue)
Now, lets say some “noise” is introduced, which changes the image to the following:
Now I can’t specify a single range and a single color, since the sequence has been interrupted. The best I could do might be to say (Pixel 1 & 3 = Blue, Pixel 2 = Yellow), which obviously takes more information to represent.
This isn’t exactly how image compression works, but hopefully you get the point that randomness interferes with compression.
In this post we showed that increasing ISO causes increased noise, which in turn causes larger file sizes due to inefficient file compression. Many of you more advanced photographers might have known some (or all) of this already, but hopefully it was illuminating for some of you.
