Exactly 20 years ago appeared in ColorFoto for the first time an article about the operating noise of cameras. Among other things, the volume was measured when rewinding a film. The author was the young editor Werner Lüttgens, who explained the advantages of the ultrasonic motor, which Canon has been using since then. There will be time for a re-presentation of the theme. Now it’s about the noise sources of digital SLR and system cameras.
The noise sources
Even if the rewinding noise of the classic film is no longer present, there is still enough noise, because the shutter, the mirror and the AF drive are still mechanically moving parts, and if something moves fast, this almost always produces mechanical vibrations Br>
Evaluation of noise
If these vibrations now have a membrane like the housing wall of a camera, they become sound, which is often perceived as disturbing. The camera manufacturers work on as quiet as possible devices. In the case of mobile phones that operate very quietly without mechanically moving parts, an artificial sound can not always be switched off.
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The measurement of the noise is similar to that of the visual, because different physical parameters are condensed into a sense impression. Usually the sound pressure is simply measured and evaluated with the so-called A-curve. Only in the frequency range of speech does the ear reach the maximum sensitivity, otherwise a lot of noise will be audible like the rumble of the bones while walking or the blood rushing in the veins.
The measurement
The specification in "dB A", however, only corresponds to the perceived loudness only with low noise. The so-called "psychoacoustical evaluation" can be approached much better by the human's sense of sound. Here, a relatively complicated calculation method is used, which as a result provides a loudness value, which is measured in the unit Sone. It takes into account the nonlinear ear sensitivity as well as the masking effect, which makes spectrally adjacent sounds appear less loud than their energy content corresponds to.
20 years ago the measured values in ColorFoto came from one of the first measuring devices, the loudness in Sone directly output and to the preferential price of 50,000 DM to be had. This can mean any PC with sound card together with a measuring microphone and the right software. We measure noise with Dr. Jordan Design's WinAudio MLS, a software package for almost all acoustic measurements. There is still a measuring microphone plus preamplifier. The measurement takes place at a distance of 30 centimeters from the test specimen.
The camera is placed on a tabletop, but is decoupled from it by foam. Since in normal rooms the background noises rise to low frequencies and the test objects in this area also hardly radiate sound, we have set the lower limit for the measurement to 200 Hertz. In our test the background level is about 2.5 Sone.
With the cameras the expectations are usually confirmed: SLRs are the pure genre, especially Nikons D800 shows a rich noise. In principle, larger camera housings have better prerequisites for emitting sound. But the Sony A99 shows that even large models are well damping. The Fujifilm X-Pro 1 and the Olympus OM-D E-M5 deliver the best performance with their well-cushioned clasps.
The mechanical shutter is still on board, because the electronic counterparts can produce serious image errors with moving objects - see box. With Panasonic you have the choice between both systems. When you set the GH2 on electronic shutter, the recording runs silently. The zoom (Lumix G Vario 3.5-5.6 / 14-42 mm Asph. OIS) also attracts attention, as the engine and the mechanical components can only be seen in the immediate vicinity.
The position of the various types of autofocus drives is complicated. The classic DC motors are out of fashion - they are crippled as spoils, because they are usually coupled to a gearbox. Ultrasonic and linear motors should be much quieter.
Buying advice The best mirrorless system cameras
However, as is often the case, the detail is important in detail: While the Fujifilm XF 2.8-4 / 18-55 mm is almost inaudible, the metallic click of the Pentax zoom SMC is 3.5-5.6 / 18 -55 mm DA AL II turn a lion's head at a distance of 300 meters. But here, too, a tenth of a millimeter of plastic would probably have sufficed on the stroke to provide peace of mind. But with this exception, all AF drives are quieter than the quietest camera.
In the diagrams the lower frequencies are located on the left, on the right the high ones, the time axis goes into the past. What appears dark blue in the plot is almost inaudible when the tips turn red, which means "quite loud."
The results
The differences between the tested cameras ranges from very quiet to disturbing. It is the Olympus OM-D E-M5 and the Fujifilm X-Pro 1. The two mirrorless system cameras are superior to the SLR competition.
With the SLRs P entax K-5 and Sony A77 are quieter than the competition of Canon and Nikon. For motifs without fast movement, an electronic shutter is the silent option. The AF engines are generally quieter than the cameras, and some of them work almost inaudibly, regardless of the system.
Conclusion
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