Hi Chuck and all,
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
>Does the IS on the E-M5 need to be disabled when on a tripod or
>partially disabled when using a monopod?
In short, according to my experience, the E-M5 IS is _always_ helpful --
even on a tripod.
When I did manual lenses' testing with the GF1, focusing was usually a
_very_ hard task, even on tripod -- the hand induced motion was affecting
the highly enlarged live view. But now, with the E-M5 and it's IBIS
available for adapted lenses (even before the exposure) all is MUCH easier.
This was the main justification for the E-M5 purchase, and so far I've been
really satisfied.
However, I've noticed something: if the _lens_ itself is mounted on a
tripod (and not the camera body) the IBIS seems somewhat _less_
effective... but helpful anyway, and definitely much better than turned
OFF. Probably the shift of the oscillation axis confuses the IBIS a bit...
>The instructions for the Canon 70-200/2.8 IS lens say to turn off the
>IS function when shooting in Bulb mode
Anyway, the E-M5's IS is't available for Bulb/Time exposures -- but it is
for manual times up to 60"!
There is a GPS accessory for the Pentax K-5 and other DSLR models that
couples with the IBIS and is able to do some _tracking_ for
astrophotography -- actually compensating the Earth's motion on a tripod!
It does have some limitations and it isn't always 100% effective but an
interesting feature anyway.
I believe that, if the camera's motion is within the _amplitude_ limits of
the system, the IS would compensate even for rather long exposure times.
From: Jim Couch <zuikoholic@xxxxxxxxxxx>
>I first noticed a problem with IS when shooting on a tripod with my E3
>and wide angle lens (9-18) corners were extremely soft.
Another observation: since the IBIS is shifting the sensor and thus getting
a somewhat larger image circle, it may increase the effect of some
aberrations at the extreme corners -- or some of them. I have noticed some
asymmetrical vignetting with my zooms on the E-M5.
>While the details are different, most of the basics apply to most
>stabilization systems, well worth a read:
><http://www.bythom.com/nikon-vr.htm>
Thanks for the link, it's an interesting read! I see Nikon's VR is said to
be 'smart enough' to detect panning properly... well, here's a difference
with the E-M5's system: it doesn't :-( Should you try to track a moving
object with a slowish shutter speed _and_ the IS fully enabled, you may end
with a blurred subject... and a perfectly sharp background -- been there,
done that.
Fortunately, it has the partial IS options: vertical or horizontal only.
But if you track some diagonally moving subject, the only way is turning
the IS totally OFF.
From: Moose <olymoose@xxxxxxxxx>
>None of this applies at all to in-body IS.
Certainly. And probably less to the multi-axis system...
>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.
Agreed, and matches my experience. I keep IS 'ON' all the time.
>As to turning it off for higher shutter speeds, I don't know.
Shouldn't make a big difference, but still helpful for manual focus. I'm
looking now at a 100% enlarged view of a 200mm shot at 1/2000 (from the OM
85-250/5 with tripod collar, mind you) and I cannot see any blurring. FWIW,
my main tripod is this one: <
http://www.flickr.com/photos/zuiko21/5657476067/>
>I seem to be finding that relying on the old 1/shutter speed rule is
>giving me sharper results, with IS on, than relying
>on the IS to give me a couple of extra stops.
I¡ve been VERY impressed with some results from the E-M5 at surprisingly
slow speeds. From my experience, the motion's _amplitude_ affects more than
exposure time... but then, a longer time increases the chance of the camera
getting off the 'shiftable' area.
What the IS seems to do then is to slow down the motion, thus going very
slow will show some blurring.
>Extra long simply puts more strain on IS?
With long lenses in silent environments, I can actually _hear_ the sensor
hitting the corners while trying to correct outside its range ;-) It's good
to keep the camera as steady as possible anyway.
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
>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.
Well, the blurring happens when _several_ parts of the image hit the _same_
sensor area within the exposure time... the effect you described of a focal
plane shutter would cause some _distortion_ of the picture but, if the
effective speed is fast enough, won't have noticeable blur.
This is hardly an issue with modern cameras, but it does show on some
cellphones, some stills-cameras when doing video... and it was the norm for
the oldest focal plane shutters on _large_ format cameras, like the Speed
Graphic -- the cartoonish cliché of a fast moving car obliquely distorted
seems to be based on actual images produced from such cameras:
<http://www.artfuldancer.com/Lessons/topics/DanceProduction/Shutters.htm>
>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.
No control system will keep zero error all the time... and with the
perceived effect of the IS actually _slowing_ down the camera's motion, the
benefit of a higher shutter speed remains.
>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.
Certainly. And if manually focusing, from the hand, too.
>Maybe the IS system can compensate for
>these as well. If not, a smart system shouldn't make it worse.
It definitely shoud, and I think it does.
Some _videocameras_ use electronic 'closed-loop' IS systems, which actually
"look" at the picture and try to shift the image to keep the objects around
the same place along the frames... those IS systems definitely _must_ be
turned off on a tripod, because they may try to follow a moving object...
But those on still cameras seem to be a sort of 'open-loop' system: they
just measure the camera's motion and, having into account the lens' focal
length, compute how much the projected image will shift and move the sensor
(or the extra element in on-lens) to compensate.
That's why you mustn't keep *both* IS systems (in-body and Panny lenses'
in-lens OIS) on at the same time: they'll detect the same camera's motion
and both will apply pretty much the same compensation... Final result: x-2x
= -x or, in other words, the recorded motion's direction will be
_reversed_, which in terms of blurring will be the same as *no* IS at all...
From: jeff keller <om-list@xxxxxxxxxxx>
>Some of the tests I saw for the 75-150 M.Zuiko showed pretty severe shake.
>I suspect the optics in the relatively loose, long telescoping AF zooms can
>move. Maybe the IS can compensate...
Do you mean the classic OM Zuiko 75-150/4, or any Micro Four Thirds
(M.Zuiko) current lens?
As for long telescopic AF zooms, I think the M.Zuiko 14-150/4-5.6 is a good
sample ;-) Despite the lightweight plastic construction, it seems pretty
decently made (at least, it didn't look "disgusting" to a Canon-L user
pro-photographer I know ;-) without the usual play of cheap kit zooms...
however, I think the E-M5's IS is less effective with this lens than, say,
with the Panny 12-35/2.8... or any adapted manual prime, I'd say. Not sure
if it's the combination of low weight, long focal and moderate speed... or
the inaccuracy of the transmitted focal lenght. Due to the 'logaritmic'
zoom scale, the highest figures just read 80-90-100-120-135-150mm, without
any intermediate values.
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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