M43 System Practice
How to test for image blur due to shutter shock
Introduction There has been ongoing discussion in M43 user forums about the vexed issue of image blur apparently or possibly or allegedly due to a hypothesised mechanical shock imparted by the first (closure) movement of the quadruple acting mechanical shutter of a M43 camera. This issue is not confined to M43 or mirrorless cameras generally. Any camera in which some mechanical part activates immediately before or during sensor exposure could potentially be prone to some kind of shock effect.
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| This is my standard Lens test target. I use the whole frame for lens tests. Many M43 lenses, even budget zooms, can, at optimum aperture, resolve all the words on the chart, even into the corners. The test target is very useful for comparing one lens with another, but of course doesn't give MTF figures or L/mm. |
DSLR vs Mirrorless It has long been known that the flipping mirror of a DSLR camera can cause "mirror slap" leading to blur at certain shutter speeds. The fix for this has been for makers to provide for some kind of mirror lock up facility. Modern DSLR's in "live view" [a.k.a. monitor view] have the mirror locked up, of course, but their shutter has to switch from the the standard two step (open-close) action in OVF view to a four step (close-open-close-open) sequence just like a mirrorless camera. Thus they could potentially be subject to the same issues with shutter shock as mirrorless cameras.
Cameras comparedI have recently been testing the Nikon D5200 DSLR, Lumix G6 and Nikon 1 V2 cameras, each with a 10-11x superzoom lens. I found that neither of the Nikons showed blur which might have been attributable to shutter shock on my tests. The D5200 only has a mechanical shutter but the first (close) action of the shutter in live view apears to be well damped, making a swishy, sliding sound. The V2 also appears to have a well damped mechanical shutter which makes a soft blp...blp... sound. The mechanical shutter of the G6 (and other Lumix cameras) makes a sharper, louder sound, possibly indicating more potential for transmission of a shock through the camera and lens. Whatever the reason the G6 does exhibit blur attributable to shutter shock (eliminated by using the E-shutter) with several lenses. The problem, when it occurs, appears to be specific to a particular camera/lens/focal length/shutter speed combination.
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| This is the G6 with Lumix 45-150mm lens on tripod, 2sec timer, at about 100mm, f5.5, 1/100 sec, ISO 800, Mechanical shutter. You can easily see it's not sharp. That's shutter shock. |
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| Now the same camera and lens, same tripod, 2sec delay, same aperture, focal length and shutter speed but with E-Shutter active. Oh, Look, now it's sharp. No mechanical shutter, no shutter shock |
The test My test procedure is quite simple. I set up a test target against a wall. This is my standard lens test target, but for shutter shock testing I just use a small portion of the center of the target. I put the camera on a tripod, select a focal length and make the following settings:
* OIS/VR off.
* 2sec timer delay or other form of wired or wireless remote shutter activation.
* Shutter Priority Mode, Auto ISO.
* I use a shutter speed range from 1/10 to 1/400 sec. I make an exposure at each 1/3 step, thus: 1/10, 1/13, 1/15, 1/20.......etc, making 17 exposures per run.
* I make the first run of exposures with the mechanical shutter active and the second run with the E-Shutter active.
* Then I download the files to the computer and inspect them at 100% on screen. Any deviation from sharpness is readily seen.
Other tests It can also be instructive to run similar tests with a hand held camera to evaluate the effect of OIS/VR On/Off and E-Shutter vs Mechanical shutter.
Results I have found that many M43 camera /lens combinations exhibit some degree of blur at one or more shutter speeds in the 1/20-1/200sec range. The worst offender I have yet encountered was the Lumix 45-175mm tele zoom which I tested two years ago and hastily sent back to the vendor. But most other lenses which I have tested, especially budget tele zooms with no OIS switch on the lens barrel ( I don't know what the significance of this might be) , show the effect to some degree.
Strategy To deal with the issue I usually switch the E-Shutter ON for general photography. For sport/action I set the shutter speed to 1/400 or faster and use the Mechanical shutter. For shutter speeds longer than 1 second (not currently available with the Lumix E-Shutter) I set Shutter Delay, which works like Olympus Anti Shock.
Hopes for the future I do so hope that sometime real soon the M43 manufacturers will save us from all this nonsense of messing around with E-Shutter/Mecha Shutter/Anti Shock/Shutter Delay and deliver a fully featured E-Shutter (like the one in the Nikon1 V2) without all the restrictions on ISO, shutter speed and flash use. Or deliver unto us the much awaited, possibly mythical, frequently spoken of in hushed tones, Global Shutter, which, if properly implemented, should eliminate the mechanical shutter altogether and make all us M43 users perpetually happy little vegemites.