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ABOUT TRIPOD, HEAD AND VIBRATION

MARCH 2005

VIBRATION AMPLITUDE [um]

not the mirror down shock but the mirror up shock that affect the picture quality.

Everything Is Important

If you want to minimize vibration, you need to take everything into account. Virtually every- thing affects the picture sharpness. The perfor- mance of the whole system is determined by the weakest part. If the lens is not well built, especial- ly the cheap standard zoom lens, the lens itself can cause a lot of vibration. Generally speaking a manual focus lens is stiffer in construction and so much stable than an auto focus lens.

Assume that you are using a state-of-the-art Digi- tal SLR camera and if your ball head cannot hold the camera stable, then you are going to waste your money. Assume you put your tripod on a ground thickly covered with autumn leaves. If you don’t push the tripod’s feet deep to the ground with spikes, then you cannot expect a stable support.

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modules is inevitable.

In case of a teleport lens, the quality of photo is affected more because of the larger magnifica- tion, heavier mass and longer length. VR lens by Nikon or IS lens by Canon or something like that is to minimize the vibration effect by controlling the ray trace in a fashion that is just the opposite of the lens vibration. It is quite helpful in hand- held shot. But these lenses are based on rota- tional vibration measurement from built-in MEMS gyro sensors, the performance would be even better if the lens is supported by a tripod. As the sensor measures rotational vibration and controls the ray based on sensing data, it can do its best when vibration occurs only in rotational direc- tion.4

VIBRATION AMPLITUDE [um]

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[Nikkor 80-400mm VR lens with Nikon F100]

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[Standard zoon lens on Sigma SD9]

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Among many parameters considered for lens selection, the build quality related to vibration should also be included. And it is quite simple. Just push any positions of the lens and you can

Above is an example of a loosely assembled cheap zoom lens. In designing these kinds of lens, motor load has to be minimized without increas- ing necessary power and cost. The assembly is loose to minimize frictional load while focusing. This means that a lot of vibration inside the lens

4 You will see more data about vibration patterns in later chapters. And your vibration controlled lens sys- tem would work best if it gets a clean, nice, symme- trical pattern of vibration. By providing such environ- ment, you give the control system a simplest set of problem.

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easily tell the difference. Avoid lenses that show more movement.

Nowadays the medium format camera seems to draw more attention from someone who aims for a higher resolution photo. Anyway most of the medium format camera is for professional use. It means that it guarantees a better perfor- mance in most situations. The mirror size of them is bigger but the weight of the body is enough heavy to compensate the effect so that the re- sulting vibration in a medium format camera is quite small and in some cases outperforms the 35mm format camera.

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[Hasselblad 205FCC with standard lens]

However, from my 3 month experience with Pen- tax67, making a shot without the MLU function was almost impossible. For me, it was the biggest shock I’ve ever experienced as for the mirror shock.

As you found here, this document contains a lot of graphs. For the people who are not accus- tomed with graphs or numbers, it would be bet- ter to have one number in mind as a reference. A common film scanner has a scanning resolu- tion of 4000dpi. This can be interpreted as a min- imum pixel size of 6.35 x 6.35um2 (0.00635 x 0.00635mm2) which is less than 10 micron in di-

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