Olympus-OM
[Top] [All Lists]

Re: [OM] E-M5 question (IS)

Subject: Re: [OM] E-M5 question (IS)
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sun, 11 Nov 2012 05:53:25 -0500
I've been rethinking his comments about shutter speed.  The statement 
essentially said that, above the flash synch speed, the sensor is never 
fully exposed due to the shutter being a traveling slit.  As the speed 
approaches the sampling frequency it becomes more and more likely that 
the image strip exposed by the slit at sampling position B are not the 
same as position B *was* when the exposure was made at position A.  In 
other words, at higher speeds there's a greater probability for blur 
since each part of the sensor can see slightly different parts of the 
image at different times... um, well, yeah... that's the definition of 
what causes blurring whether over the full sensor or just part of it.

After rethinking this I've come to the conclusion that this is 
absolutely true but... meaningless with respect to shutter speed. 
Irrespective of the IS system's sampling speed (relative to shutter 
speed) the IS system's ability to compensate for camera motion is 
exactly the same whether the shutter speed is 1/60 second or 1/4000 
second.  So it remains true that a 1/4000 second exposure will show less 
blur than a 1/60 second exposure.  Whether or not the IS system is truly 
effective at 1/4000 second will be dependent on the sampling and 
response frequency of the system.  But regardless, the 1/4000 second 
exposure will have less blur than the 1/60 second exposure whether the 
IS system is fully compensating or not.  It can only make it better but 
not worse.

Thinking further, maybe the IS system should be left on when on a 
tripod. The camera on a tripod is still subject to ground vibrations and 
shutter/aperture vibrations.  Maybe the IS system can compensate for 
these as well.  If not, a smart system shouldn't make it worse.

Chuck Norcutt


On 11/10/2012 7:36 PM, Moose wrote:
> It's impossible to know about sampling frequency without knowing what it is 
> on various IS systems. Most of the rest
> either doesn't apply, we already know or is common sense.
>
<snip>
>
> My conclusion? Forgetting to turn off E-M5 IS on a tripod isn't such a bad 
> thing. The E-M5, six axis IS system is quite
> different from both 4/3 and preceding µ4/3 cameras, so I don't believe my 
> result is generalizable.
>
> As to turning it off for higher shutter speeds, I don't know. I would have a 
> problem with that in the field. One of my
> lenses goes out to 600 mm eq., which I use not infrequently. That requires 
> 1/600 without IS, more, really, with the
> ability to pixel peep if one might crop or print large.
-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz