Shutter Shock: My ep5 is bad. Would an em5 do better?

Started Jan 26, 2014 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: More test data with various settings, noticeable improvement.

skyglider wrote:

Anders W wrote:

I tried to find some additional literature on how these shutters actually work. What I have found so far is mainly patents (which are a bit time-consuming to read and understand). The one to which I link below, however, suggests that the Wikipedia article on focal-plane shutters that I have previously relied on is partly wrong.

It talks about "drive springs", which suggests that even modern shutters are in fact spring-loaded, with the coreless motor used for cocking/loading/charging the springs rather than for directly driving the shutter blades.

As to your questions: Not only can the first curtain be "cocked" before it is closed to prepare the sensor for exposure. If I understand things right, it must be "cocked" in order to move. Whether subsequent phases of shutter action are "cocked" only after the first curtain has made it first move or are somehow "precocked" is not yet clear to me.

Hi Anders,

Here's my current hypothesis of how the first curtain shutter works in the E-M1:

The first curtain shutter is made of two parts. One is a metal piece with substantial mass which is required for an electromagnet to pull it up. This metal piece is connected to the light first curtain shutter blade with springs.

When the shutter button is pressed, the electromagnet activates which pulls the metal piece up which in turn pulls the first curtain shutter up to the closed position. Because of the mass of the metal piece, the impact of it hitting the electromagnet causes substantial vibrations in the camera, resulting in substantial shutter shock.

When short release lag time is enabled it activates the electromagnet which pulls the metal piece up. This accounts for the "clunk" sound heard when short release lag-time is enabled. But the light shutter blade is still held in the down (open) position. The shutter blade is then "cocked" ready for release. --- When the shutter button is pressed, the first curtain shutter blade is released which allows the springs to pull the shutter blade up closing the shutter. --- Since the shutter blade is light, it can close very quickly and also results in substantially less vibration when it impacts at the closed position. Result is minimal shutter shock.

This short release lag-time hypothesis would explain why more battery is used and why Olympus warns against bumping the camera which can cause inadvertent release of the shutter blade, closing the shutter and causing the display to be lost on the screen or in the view finder.

What do you think?

Hi Sky,

I don't pretend to be an expert on the inner life of shutters. But if you ask me what I think at this point (without having had a whole lot of time to read up on the subject) that's not how I would guess it works. I don't think either of the curtains are operated by electromagnetic force in the manner you suggest or that they include any (relatively) heavy part.

Rather I think both curtains are very light (as light as they can be made without breaking) and that they might be driven by springs charged by one or more coreless micro motors. The shutter curtains of the E-P5 move with an average speed of about 5 m/s, which in turn implies forces large enough to cause problems even if the curtains are very light. Charging the mechanism may also put sufficiently large forces at play, and at least part of this charging apparently takes place after each exposure when the release lag-time is set to short whereas it takes place immediately before the shutter goes into action when the release lag-time is set to normal, thereby increasing the risk that it will affect the exposure.

That's just my provisional account at the moment and it may well be more or less wrong or incomplete.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
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