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Looking at this forum, I have seen many posts wondering why Image Stabilisation (I.S.) is not available on all modes on the Sony Ericsson K800i!
The issue seems to be that people are confusing I.S. on a Video camera to I.S. on a Still Camera. Both have different goals; in the case of Video, we are talking "intra-frame" movement stabilisation, whilst in a still camera we are looking at motion blur within the frame itself. In essence in video you are trying to "smooth" the jittery motion across many frames that occurs from a shaky hand or other vibrations. In a still photo, you are trying to reduce the motion blurring that occurs in a single frame, from the same sort of vibrations.
As a photographer (and videographer) I am going to write a little bit about my experiences of I.S., and why SE's offering is actually quite adequate.
In a video camera, IS is used to reduce the appearance of a shaky video on the final recorded item. A video camera has a shutter speed of 1/50 (PAL) or 1/60 (NTSC) or faster. Image stabilisation prevents camera shake from appearing between the different Frames. Thanks to the high frame rates, motion blur on each FRAME is already reduced, therefore "interframe" image stabilisation techniques are not necessary.
In still photography, there is only one "frame" there is no need to compensate between different frames. However sometimes there is a need to take photos with longer exposure times, such as low light, or to blur the water in the "waterfall".
In still photography (digital and film) IS is used to help prevent motion blur in long exposure shots. A long exposure shot typically has a shutter speed significantly slower than 1/60 sec (typically from 1/15 to 30 seconds, with even longer exposures used to capture stars) and are used to allow more "light" onto the film/sensor to take clear low ISO pics in low light situations. However, long exposures make the camera more susceptible to motion blur, when not used with a tripod. IS helps reduce motion blur, allowing you to use up to 2 or 3 times slower shutter speed (Eqiv to EV.2) than would be possible without, and therefore gives greater flexibility with the ISO and Exposure settings. However, please note, at a shutter speed of anything faster than 1/30 or 1/60, motion blur is pretty low anyway, unless you are really not holding your camera right.
There are Three ways of doing Image Stabilisation.
(See
http://en.wikipedia.org/wiki/Image_stabilisation for more information)
The cheapest and most effective method is simply use a flash, or increase the lighting. Using a flash effectively "freezes" an image, and also provides more reflected light to the sensor, reducing required exposure time by huge amounts, effectively stopping motion blur.
The K800i has a flash sync of 1/250 (which is higher than my Canon EOS 350D which syncs at 1/200). At that sort of shutter speed, motion blur is virtually impossible, and Image stabilisation is NOT NEEDED AT ALL!
Its that simple, More light = faster shutter speed = reduced motion blur. Using a flash, or increasing the available light is perfect for 95% of shots, especially pictures of YOUNGER people, who cannot stay still. It helps freeze motion, and can cope well if the object being photographed is moving. IT doesn't matter whether you have an expensive DSLR, or a cheap camera phone, you need light, and lots of it. The K800 provides a flash, which is more than adequate for most situations. The K800i also provides a "Twighlight Portrait Mode" which was very surprising. This mode does uses the flash to "freeze" the person you are taking, but then holds the shutter open to capture as much light from the background as possible, to give a more natural picture. Despite the slower shutter speed, there is little need for Image Stabilisation, as the Flash effectively froze the image. There may be some blur in the background, but that may actually be a more pleasing effect, as it helps to make the much sharper foreground stand out.
Another form of image stabilisation is Optical (OIS). In this system, either there is a moving lens, or the sensor itself moves, in response to movement of the camera. This is an effective technique, and can help allow a photographer to use a longer shutter than normally possible when taking hand-held shots (it has very little effect when using a tripod, unless you are using extremely long shutters). Optical IS does not eliminate blur where the object itself is moving, an may even cause an effect where the background stationary objects are sharp and the moving object is blurred.
OIS is ideal for landscape photos, where focus is near infinity. However, it still requires you to hold the camera as still as possible. Its certainly not a miracle cure. When used with a flash and short exposure times, its pointless, as the flash is vastly more effective. With longer exposure exposure times and flash, OIS MAY help reduce the blur on the BACKGROUND. In fact the use of flash pretty much eliminates the use of optical IS. Fitting OIS is probably too complex on a camera phone the size if the K800i.
The third and final form of I.S. is digital Image Stabilisation. This is what exists in the K800. Digital IS works by using less of the sensor to capture the image. Effectively it has a smaller "virtual frame" within the sensor. As the camera itself moves, Imaging electronics continually takes "pictures" at high speed. each picture is analysed with the previous picture. Using key points in the picture, the electronics decide which part of the picture to take, effectively simulating a moving sensor. This technique is very effective in Video cameras, as they do continuously take separate frames of video. In a still camera its not so effective. Firstly, for it to work, it needs to take MANY pictures at short exposure times. Each picture is analysed, and then trimmed to eliminate the movement. Then finally they are combined (added) on top of each other to give the effect of a longer exposure image. This technique is cheap, and simple to produce but has many disadvantages:
- reduced picture size, as a border is "wasted" in trying to simulate a moving sensor
- Cannot be used with flash, unlike Optical IS
- increased picture taking time. IT may take up to 1 second to take a shot, that simulates a .5 sec exposure, making it difficult to work with moving objects, such as people. It is harder to make them stay still for One second, as opposed to half a second.
AS you can see, This form of IS is pointless for when you are taking people, or moving objects. It induces artefacts of its own. Therefore the only places where it would be useful is when taking pictures of landscapes, in low light. (Landscapes in good light does not need IS).
I hope this demystifies what IS means in still cameras, and also explains why its only available in certain modes. Not because Sony Ericsson's want you to buy a more expensive camera, but simply because its pointless in other modes, especially where they have given the ultimate image stabiliser, the Flash!
If you are still getting blur when using a flash, this may be down to poor focus, rather than motion blur. Try and focus on a high contrast area first.
[Edited to clean up my grammar, this is what happens when you post from work!]
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Owned (order of purchase): Nok 8110, Nok 6150, Nok 8210, Nok 6210, Eric r320s, Eric T68m, SE T300, SE P800, SE T610, SE S700i, Mot V3i, SE K800i
[ This Message was edited by: janahan on 2007-02-20 12:13 ]
[ This Message was edited by: janahan on 2007-02-20 12:23 ]
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Posted: 2007-02-19 13:52:44
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That's a great post. Thumb up for you.
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Posted: 2007-02-19 15:04:00
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As a photographer using bigger cams, I agree. The only true image stabiliization is the gyrpscopic stabilization, and of all cams I tried, the Panasonic FZ50 has the best implementation of IS. Canon's S2IS/S3IS have got the worst, I must say, while Sony H2/H5 are somewhere in between.
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Posted: 2007-02-19 15:16:52
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Wow guys! I am moved. I am glad that esato is not only about bashing non SE brands but educational as well! Great posts!
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Posted: 2007-02-19 15:20:42
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very useful and helpful post. this should become a sticky post sooner or later.
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"Piracy, not. MP3, hell yeah!"
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i've 
myself[ This Message was edited by: tranced on 2007-02-19 14:25 ]
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Posted: 2007-02-19 15:24:07
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Quote:
On 2007-02-19 15:16:52, IRFCA_WDG-3A wrote:
The only true image stabiliization is the gyrpscopic stabilization.
x2 to that.
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Posted: 2007-02-19 16:45:45
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A very useful post indeed, definitely enlightened me regarding many aspects of IS. Good one, @janahan!
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Posted: 2007-02-19 16:52:05
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Very useful indeed, will have a proper read when I get home!
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Posted: 2007-02-19 17:27:41
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Very interesting. Thanks for that janahan
Kwiksta
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Posted: 2007-02-19 19:26:37
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really helpfull and professional!!
OFFTOPIC-janahan...so how happy are you with the k8?i mean being a pro photographer,wats you opinion on the SE Cyber-shot camera?
R
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Posted: 2007-02-19 19:32:15
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