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Old Oct 22, 2002, 1:59 PM   #1
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Default Image Stabilisation (IS)

I emailed the digital photography magazine which I subscribe to asking why so few digicams have IS when so many camcorders have it. Well here's the answer assuming it's correct that is. Makes interesting reading anyway.

Image stablisation works well for camcorders because it is based on a moving image system. What happens is that whenever the camcorder gets a focus lock it buffers frames until the viewpoint changes suddenly, as tends to happen when at the end of a telephoto zoom. While the camcorder tries to refocus on what it is now looking at, those frames in the buffer that are the most recent are recycled back into process so as to give what looks like a stable picture. The system works best when simply dealing with a shaky hand or a bit of wind, but essentially where the user is trying to video the same place.

So, why isn't it used in digital cameras? For a start, instead of talking about an image 640*480 resolution or lower in the case of video, you are talking about ones that are 2272x1712 or 2560x1920 in size for digital photography and those files are much bigger, require more processing power to cycle round a buffer, and obviously take much longer to be scanned to see if they are radically different from what has gone before. Just like video cameras, most digital cameras are constantly cycling frames through the CCD, they aren't just waiting for you to press the button, but they are doing it in low resolution for the benefit of the LCD monitor so you can have a real time view on it. The camera you are talking about that did have it, was only a 2.1Mp or 1600x1200 resolution device. Lower memory and processing overheads.

The other practical reason why image stabilisation isn't seen on most cameras is because digital video is a poor-quality medium, whereas digital stills have to be as high a quality as possible. The reason you would want image stabilisation is because the shutter speed is going to be too low and result in camera shake. If the amount of available light is quite low and you did have IS then the shutter speed wouldn't be fast enough for it to work properly. You would end up having to have the camera on completely automatic, just to let it get the shutter speed up high enough to get any stable pictures.

In other words, as camera resolutions increase, there is less chance of seeing it be implemented, but at some point in the future, processing speeds and chip sensitivities will be so advanced that I can see them catching up. In 10 years time your 20Mp SLR could well have fully functional image stabilisation.
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Old Oct 23, 2002, 4:55 AM   #2
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Makes sense!
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Old Oct 23, 2002, 9:09 AM   #3
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I've read that the C-2100 IS is mechanical, using gyros, not electronic. Also, the IS system is of use not only for low light but also for long zoom.
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Old Oct 23, 2002, 12:00 PM   #4
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My friend's Canon comcorder has mechanical IS (eats bats when on). This maybe the type Canon have patented and have withdrawn permissions to certain companies.
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Old Oct 23, 2002, 3:04 PM   #5
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Here's a page that shows how the mechanical gyro IS system works (from Canon):

http://www.canon.com/technology/opti...ift/index.html
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Old Oct 30, 2002, 6:54 PM   #6
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Steve...

Thanks for taking the time to share such a graphic explanation of digital camera IS. This is a question all of us ponder and tend to conclude without research. Your post cleared a lot of air and like one of the fellas simply said...'makes sense'.

Don
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Old Nov 1, 2002, 10:18 AM   #7
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'makes sense' indeed.

But, I think those stating that the 2100's IS system is also mechanical are right. The camera uses a hell of a lot less bateries when turned on, and also makes less noise (listen carefully, as this camera is very silent in any mode).

Additionally, unlike video, having multiple 'partial' frames then can be re-centred work for video, but not for still images.

If a 'shake' offsets a video frame 20 'lines' up, nobody will notice if the frame is electronically shifted, and the 20 lines are 'filled' with data from a frame that has 'base' position. This is because the resolution is so much lower so the 'seams' between the shifted image and the 'guestimated' part of the image wont be noticed (especially not since those IS's only work with mild shaking, so its only a couple of lines that's shifted, and the 'filled' blank caused by the shifting is outside of the 'visible area'.

However, for s 'still' image, you do need an exact single full frame as photographic camera's will have each pixel captured visible in the end result. Shifting and 'filling in the blanks caused by shifting' would always show.

The two methods of IS (image-shifting v.s. optical element shifting) are completely different in concept and both have their use.

What strengtens my suspicion that the 2100's is indeed both mechanical and gyro-based is the 'sluggishness' of how the view in the viewfinder 'follows' when panning with IS turned on. This effect does not show in 'image shifting' IS implementations (try panning with a C2100, and then with a IS videocam, you'll see what I mean).

Anyhow, just my 2ct's. And my guest is that cost, delicacy ('floating' elements), and taking up space inside the body of the cam are more likely reasons not to employ to much IS in digicams.

Additionally, why make a 6mp digicam with a 400mm IS lens to sell for (let's say) $2000 ????
I'll explain why not:
It's more profitable to make 6mp body's and keep selling the big 35mm size sensor oriented $6000 lenses.

Let's face it. What does a 2nd hand 2100 cost now? Compare this to the cost of a 35mm camera (doesnt even have to be digital) + a 400mm IS lens!!!!! Well, if you dont need to enlarge beyond 8x10''s, the difference in price is enourmous, while the difference in end-result and userfriendliness (lightweight) is propably in favor of the c2100. (yes I know, can't get 300dpi 8x10 out of 2.1mp, but the lens is pretty good, and some nifty technique is required to get to a decent 35mm negative at 400mm that enlarges to 8x10 better then the c2100's output).

again, just my 2ct's
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Old Nov 1, 2002, 3:34 PM   #8
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So far all of the digital still cameras have employed a true mechanical IS system. This is easy to see, just look at the size of the lens "snout" on the C-2100UZ, E-100RS, Pro90 IS, FD-91, FD-95, FD-97 and CD-1000. You need a big lens to house the gyro system that "floats" the optical lens inside.

Just food for thought.

-Steve
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Old Nov 1, 2002, 11:48 PM   #9
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What about the Panasonic Lumix DMC-FZ1...does that also have the mechanical system, because the lens looks pretty streamlined (unlike the C-2100).
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