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ABOUT TRIPOD, HEAD AND VIBRATION

MARCH 2005

ABOUT

This article is an update of my previous writing about vibration in camera support. It was first published on-line in January 2004 and this is the 4th major revision.

March 2005 Written by Charlie Kim Copyright ©1 by Charlie Kim and Markins

October 2007: Minor corrections and copyright information is revised.

INTRODUCTION

[Testing tripod-head vibration at the Markins of- fice using Nikon D2H, laser vibrometer and data acquisition system]

Even with some decades of advancement in camera technologies, stable support with tripod is the most promising way to get a sharper pic- ture. Even with fancy control algorithms for vibra- tion reduction, using tripod is the only practical solution that gives us freedom in photography.

I begin this article showing two most common and well known examples of camera related vibrations. One is about MLU (Mirror Lock Up Function) and the other is about the need for a higher shutter speed.

True understanding is about a different manner of doing something. When you understand how much you lose by not using tripod, you may not be able to make a single shot without one.

1 All rights reserved in all countries. No part of this ar- ticle may be reproduced in any form or by any elec- tronic or mechanical means including information storage and retrieval systems without permission in writing from the author, except by a reviewer who may quote brief passages in a review.

Mirror Lock Up

Mirror and shutter are the main moving parts in- side the camera. If there is no external vibration, those are the only sources of camera vibration. The vibration caused by mirror collision is quite big in most cameras. 2 Following graphs suggest how much the vibrations caused by it would be.

For this measurement Hasselblad 205FCC with

Contact information: charlie@charliekim.com http://www.markins.com/

2 John Shaw said that the camera without MLU is not a camera.

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standard 80mm lens was used.3

VIBRATION AMPLITUDE [um]

40

mirror up

1st curtain stop

20

35.4um

2nd curtain stop

0

  • -

    20

  • -

    40

0.1

1/8 sec

mirror down

0.2 0.3 TIME IN SECOND

0.4

0.5

VIBRATION AMPLITUDE [um]

40

20

0

  • -

    20

  • -

    40

0.0

1st curtain stop

2nd curtain stop

5.1um

1/8 sec

mirror down

0.1

0.2 0.3 TIME IN SECOND

0.4

You can see the start and stop signs of every event. If your camera has a MLU function, there is no reason not to use it. If not, your camera should provide a really nice breaking mechan- ism to reduce the mirror shock. When it comes to a mirror shock issues, some cameras are good, some are bad. But it should be noted that it’s

3 It should be noted here that the signal level was big due to an improper floor-spike combination. All the vibration energy provided by mirror shock was bounced from the hard laboratory basement floor. But I still want to present this data because it shows the patterns of shock and vibration in detail. You can see the typical response of my Hasselblad 205FCC in later part of this document.

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