达清夫发现，对于大多数地震来说，震中附近的时间间隔都很短；震中指的是地表上震动最强烈的地方。

For most earthquakes, Wadati discovered, the interval was quite short near the epicenter; the point on the surface where shaking is strongest.

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但另一方面，镜片震动相对于曝光时间短得可以忽略不计，因此，反光镜锁定对夜间摄影并非必要。

On the other hand, mirror shake is negligible for exposures much longer than this; therefore MLU is not critical for most night photography.

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由此，镜面翻转造成的震动就有时间在曝光开始前缓和下来。

This way, any vibrations induced by the mirror have time to settle down before the exposure begins.

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Here is the pitch in--of--a string an octave higher so you can see it this way. As you probably know, if you take a long string and pluck it, it's going to take that long string a long time to pass that sort of cycle, if you will, just one pass through that cycle.

这也是个音高,一个高八度的音弦,你可以这样这样看 你们可能知道,如果你拨动长弦,长弦要经过很长时间,才能完成一个震动周期,如果你想,可以尝试下

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