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PostPosted: Sun Jun 24, 2007 12:31 pm 
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Maybe this is not a specific Olympus item, but I was triggered to write this after the remark made in de E510 review.

Like on many other sites or in magazines, the assumption was that lens based stabilisation would or could work better then camera based stabilisation. I have even read that camera based stabilisation would be less effective with long tele lenses.

I have read this many times, but always as a remark, never based on actual facts or tests. So is it true? To be honest I strongly doubt it. It seems to me, it has been said so many times that people actually start believing it and start repeating it.

So why do I doubt it?
Basically motion blur is caused by movement of the camera (and by the subject) and mostly by rotation (it's hard to point a camera at a fixed point). The amount of movement = angle x distance. So if the distance is 20 m instead of 10 m, the movement on the sensor will be double.

The fact is that tele shots should be taken at higher shutter speeds. The rule of thumb says: with a 200 mm lens the shutter speed should be 1/200 and with 400 mm it should be 1/400.

In other words, if the tele is double, the movement will be double, but because of the faster shutter speed, the motion on the sensor will be the same.

Conclusion: sensor based stabilisation will work just as well on wide angle as on tele lenses, it will reduce the shutter speed needed. If optical stabilisation will work better, remains to be seen. The motion to be compensated is still the same and if it will be compensated in the lens or in the body seems to make no difference.

Hans


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PostPosted: Sun Jun 24, 2007 2:33 pm 
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I'm quite sure that camera based anti-shake is driven by motion sensors in the cam. So if you move the cam a little the shake is then registered and the sensor moved in the other direction. But with a tele-lens the same amount of camera-shake makes for a much bigger jump in the picture, so the cam has to be aware of the focal length of the lens to compensate accordingly. If this compensation for focal length (plus perhaps the amount that the centre of mass is shifted with a bigger tele-zoom) is not correctly factored into the anti-shake calculation, then the body-based antishake will loose against an optimally adapted lens based sensor.

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PostPosted: Sun Jun 24, 2007 9:01 pm 
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tombomba2 wrote:
But with a tele-lens the same amount of camera-shake makes for a much bigger jump in the picture

This is true if you would consider the same shutter speed, but you are not.
Anti shake will give the opportunity to use 2 or 3 times longer shutter speeds, so with a 50 mm lens you will go from 1/50 to 1/10 or something like that and with a 500 mm lens from 1/500 to 1/100.

Hans


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PostPosted: Sun Jun 24, 2007 9:15 pm 
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Yeah, you're right Hans!
But with the shorter shutter speed the compensation has to occur faster.
So even when you "shake" say 10 pixels at 50mm in 1/50 sec you'll end up 10 pixels at 500mm in 1/500 sec. So you have to shift the sensor 10times as fast for the same amount of pixels.
And that's the real challenge for body based anti-shake :idea:

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PostPosted: Sun Jun 24, 2007 10:17 pm 
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I think you're both right. You would use faster shutter speeds at longer focal lengths, but whether they'd be sufficient to counteract the greater strains on the in-camera system's abilities and response time is the big question.

I'm currently doing some tests with the E-510 and a much longer lens to see how well the system scales and will report back in a future article...

Gordon

PS - Hans, I presume you've also seen this page, right?

http://www.cameralabs.com/reviews/Olymp ... 50mm.shtml


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PostPosted: Sun Jun 24, 2007 10:51 pm 
I remember reading a review of a Canon lens with IS which didn't performed as good as the non-IS version where they thought it might be because of the IS. I will try to see if I can find it again.

Edit: found it here


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PostPosted: Mon Jun 25, 2007 11:02 am 
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Gordon Laing wrote:
PS - Hans, I presume you've also seen this page, right?

http://www.cameralabs.com/reviews/Olymp ... 50mm.shtml

Yes, I've seen it.


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PostPosted: Mon Jun 25, 2007 11:15 am 
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tombomba2 wrote:
Yeah, you're right Hans!
But with the shorter shutter speed the compensation has to occur faster.
So even when you "shake" say 10 pixels at 50mm in 1/50 sec you'll end up 10 pixels at 500mm in 1/500 sec. So you have to shift the sensor 10times as fast for the same amount of pixels.
And that's the real challenge for body based anti-shake :idea:

That's not completely true.
Yes the time is faster, but the rotation to be compensated is less.
Let's say the rotation during 1/50 s is phi, then the movement at 10 m is 10phi and at 100 m (tele) it will be 100phi. During 1/500 s the rotation is 1/10phi. So 10 times as fast, but also 1/10 of the rotation.

Actually there will not be a fixed rotation, but a random movement (rotation) back and forth. If the IS is gyroscopically based, it would actually work better with fast movements in stead of slow movements.

Anyway, my point is: don't write that lens based IS works better, unless there are tests which confirm this.

I'm looking forward to the tests with the E-510 and a much longer lens. :)


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PostPosted: Thu Sep 20, 2007 4:08 pm 
here's a test on the difference between lens IS and body IS:
http://www.popphoto.com/cameras/4615/im ... shake.html

Gordon, I would love to see a review of the Oly 510 with a Leica Mega OIS 14-150 when it comes out.


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PostPosted: Thu Sep 20, 2007 11:36 pm 
Plus is a lot cheaper on the lens too for inbuild IS.


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PostPosted: Fri Sep 21, 2007 7:32 am 
After seeing how much extra an IS lens cost and that lens based IS is reducing the optical quality then I'm beginning to question which is better. If lens based IS is in generel not even better than camera based IS then the choice is even easier...


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PostPosted: Fri Sep 21, 2007 11:26 am 
LOL, if only it was that simple. For every one review you read for it there is one against it.

But I would prefer it on board camera.


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PostPosted: Sat Sep 22, 2007 1:34 am 
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Hi cderaaf, I will be testing the 14-150mm when it comes out, but haven't decided on the body yet. I'd have thought a non-stabilised body would be the best bet, as we've already seen how a lens with IS will not work with an IS-based body if both aren't aware of each other - and as I understand it, the E-510 isn't designed to work with IS lenses...

Not sure if you saw our article and video about what happens when you mount a stabilised lens on the E-510, but if you missed it, check it out here:

http://www.cameralabs.com/reviews/Olymp ... 50mm.shtml

Gordon


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PostPosted: Sat Sep 22, 2007 2:27 pm 
But if you have in built IS why would you be buying an IS lens?

At the end of the day as long as you can get a quality lens without the IS you are gonna save money, and the IS in the 510 does the job.


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PostPosted: Sat Sep 22, 2007 11:07 pm 
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Hi Wonda Boy, I think the question is whether the combination of in-body plus in-lens anti-shake could give you the possibility of double stabilisation! I believe this is possible if both systems are aware of each other and can work together - but sadly that's not the case for the E-510.


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