Luminous Landscape Forum
Site & Board Matters => About This Site => Topic started by: John Camp on January 25, 2007, 01:44:26 pm
-
I didn't know what was the appropriate forum for this, but since Michael reviewed the G7 and there was a long discussion about the missing RAW on this one, I post it here...
The Askey forum has a news note on a new Olympus P&S, the SP550, which has an 18x (!!!) zoom lens -- 35mm equivalent of 28-504 -- with image stabilization, which it probably desperately needs at the long end. Anyway, the length of the zoom made me laugh. Other stuff is pretty interesting: 7.1 mp chip, which meant that they stayed clear of the MP race, and some of the 7 mp chips have been really good. Also, it has RAW. If the high ISO capability is there, and it could be (has settings for ISO 50-5000) with the slightly larger pixels of the 7mp chip, and if the glass is up to Olympus' higher standards...it could be a contender.
On the downside: electronic view finder.
JC
-
I didn't know what was the appropriate forum for this, but since Michael reviewed the G7 and there was a long discussion about the missing RAW on this one, I post it here...
The Askey forum has a news note on a new Olympus P&S, the SP550, which has an 18x (!!!) zoom lens -- 35mm equivalent of 28-504 -- with image stabilization, which it probably desperately needs at the long end. Anyway, the length of the zoom made me laugh. Other stuff is pretty interesting: 7.1 mp chip, which meant that they stayed clear of the MP race, and some of the 7 mp chips have been really good. Also, it has RAW. If the high ISO capability is there, and it could be (has settings for ISO 50-5000) with the slightly larger pixels of the 7mp chip, and if the glass is up to Olympus' higher standards...it could be a contender.
On the downside: electronic view finder.
JC
[a href=\"index.php?act=findpost&pid=97518\"][{POST_SNAPBACK}][/a]
The CCD is a 1/2.5", so I'd take the ISO 5000 with a big grain of salt. Also, the IS is CCD-shift rather than lens element, so it's effects would be less at that really extreme range. The 15fps feature is interesting, though. I wonder if it combines with the ISO 5000?
I'm sure it'll be a success, though. It has all the high numbers and right buzzwords.
-Lars
-
The "downside" is not the electronic viewfinder; it's the size and bulk of the thing. You might as well carry a small dslr. It might turn out to be a nice camera for the post p&s / pre-dslr market but slipping it into a pocket would present a challenge.
My G7's secure.
-
The "downside" is not the electronic viewfinder; it's the size and bulk of the thing. You might as well carry a small dslr. It might turn out to be a nice camera for the post p&s / pre-dslr market but slipping it into a pocket would present a challenge.
My G7's secure.
[a href=\"index.php?act=findpost&pid=97582\"][{POST_SNAPBACK}][/a]
It is a chubby little thing; it's 4/10s of an inch longer, 3/10s taller, but almost an inch an a half thicker. It's not for the pocket but I think it might be okay for a briefcase. Main question will be image quality. I'll stick with my G7 as well. Wonder if somebody could hack a RAW option?
JC
-
The CCD is a 1/2.5", so I'd take the ISO 5000 with a big grain of salt. ... The 15fps feature is interesting, though. I wonder if it combines with the ISO 5000?
[a href=\"index.php?act=findpost&pid=97527\"][{POST_SNAPBACK}][/a]
The ISO 5000 and the 15fps are both at lower resolution than the full 7MP, so some kind of down-sampling or binning are used. That could make the ISO 5000 useful to salvage situations where only small images are needed (for web pages or 4"x6" sized prints?) under low light conditions.
-
Also, the IS is CCD-shift rather than lens element, so it's effects would be less at that really extreme range. [a href=\"index.php?act=findpost&pid=97527\"][{POST_SNAPBACK}][/a]
According to the news item at Dpreview, the camera boasts a 'Dual Image Stabilisation". Does this mean a combination of optical IS and sensor shift, something that was considered unworkable in another thread here recently, or does it mean a combination of optical IS and 'pixel' shift, which video cameras tend to use, or are these concepts one and the same?
It's perhaps interesting to note that at the widest aperture, at the longest reach of 500mm, F4.5, such a tiny sensor produces an equivalent DoF on 35mm format of f27.
With a zoom lens such as the 100-400 IS and 1.4x extender on the 5D (a slightly greater reach than the SP-550, but not by much) F27 produces shots almost as sharp as the sharpest apertures of f11-f22.
I would expect any half decent 35mm lens to be very much diffraction limited at f27. For the SP-550 to produce sharp results at 500mm, the lens would have to be diffraction limited at f4.5. It is very doubtful that it would be.
-
According to the news item at Dpreview, the camera boasts a 'Dual Image Stabilisation". Does this mean a combination of optical IS and sensor shift, something that was considered unworkable in another thread here recently, or does it mean a combination of optical IS and 'pixel' shift, which video cameras tend to use, or are these concepts one and the same?
[a href=\"index.php?act=findpost&pid=98195\"][{POST_SNAPBACK}][/a]
My recollection is that the "dual" is a reference to the ccd shift (fine) and that b.s. about futzing with the ISO (not fine).
-
My recollection is that the "dual" is a reference to the ccd shift (fine) and that b.s. about futzing with the ISO (not fine).
[a href=\"index.php?act=findpost&pid=98203\"][{POST_SNAPBACK}][/a]
The specifications shown on Dpreview clearly state that IS is optical.
-
My recollection is that the "dual" is a reference to the ccd shift (fine) and that b.s. about futzing with the ISO (not fine).
[a href=\"index.php?act=findpost&pid=98203\"][{POST_SNAPBACK}][/a]
I'm pretty sure that's the case, too. The description "Enjoy double protection against camera shake with Dual Image Stabilization. Even at high magnifications or when capturing fast-moving objects, this technology ensures results are significantly sharper" also seems to indicate this, as lens shift would do nothing for fast-moving objects. DPReview's own description calls it CCD-shift stabilization.
-Lars
-
I'm pretty sure that's the case, too. The description "Enjoy double protection against camera shake with Dual Image Stabilization. Even at high magnifications or when capturing fast-moving objects, this technology ensures results are significantly sharper" also seems to indicate this, as lens shift would do nothing for fast-moving objects. DPReview's own description calls it CCD-shift stabilization.
-Lars
[a href=\"index.php?act=findpost&pid=98303\"][{POST_SNAPBACK}][/a]
Where's the 'dual' and where's the 'optical'. It's fair to mislead in advertising, apparently, as long as you don't tell blatant lies.
-
Here's a link to Phil Askey's rant on this topic...
http://www.dpreview.com/news/0701/07010501...abilization.asp (http://www.dpreview.com/news/0701/07010501notimagestabilization.asp)
-
Here's a link to Phil Askey's rant on this topic...
http://www.dpreview.com/news/0701/07010501...abilization.asp (http://www.dpreview.com/news/0701/07010501notimagestabilization.asp)
[a href=\"index.php?act=findpost&pid=98412\"][{POST_SNAPBACK}][/a]
Tim,
The rant does not address the SP-550's claim of optical image stabilisation. The specifications clearly state this lens has optical image stabilisation. We all understand what that means. If they go further and claim 'dual' image stabilisation, which they have done, then we might wonder what this means.
-
It doesn't say dual OPTICAL stabilization. The marketing types are claiming there are 2 ways to stabilize 1: CCD shift and 2: automatically bump up the ISO. They're just using double speak to say there are 2 ways to reduce camera induced blur, with one being the amazing technique of increasing the shutter speed - WOW how's that for innovation. Phil's rant is directed at the marketing hype claiming that bumping up the ISO is some kind of stabilization.
Regardless of the shadiness of the practice surely there's no mystery surrounding what they mean after you cut through the hype.
Or maybe your issue is their claim that ccd shif is "optical"?
-
It doesn't say dual OPTICAL stabilization. The marketing types are claiming there are 2 ways to stabilize 1: CCD shift and 2: automatically bump up the ISO. They're just using double speak to say there are 2 ways to reduce camera induced blur, with one being the amazing technique of increasing the shutter speed - WOW how's that for innovation. Phil's rant is directed at the marketing hype claiming that bumping up the ISO is some kind of stabilization.
Regardless of the shadiness of the practice surely there's no mystery surrounding what they mean after you cut through the hype.
Or maybe your issue is their claim that ccd shif is "optical"?
[a href=\"index.php?act=findpost&pid=98438\"][{POST_SNAPBACK}][/a]
Of course the specs do not say 'dual optical stabilisation'. There would seem to be no point in that. You either have optical image satbilisation or you don't. Reading the Dpreview specs, they mention optical image stabilisation. Elsewhere they mention 'Dual image Stabilisation'.
I'm simply putting 2 and 2 together. Is it dual or not? If it's dual, then it's dual because it combines optical with some sort of CCD shift. If it doesn't, then what is it?
-
I'm simply putting 2 and 2 together. Is it dual or not? If it's dual, then it's dual because it combines optical with some sort of CCD shift. If it doesn't, then what is it?
[a href=\"index.php?act=findpost&pid=98446\"][{POST_SNAPBACK}][/a]
I just can't imagine sensor-shift and optical IS working together; there is just too much detail in communication needed to keep them both from correcting the same thing! Two corrections = 1 error.
Most likely, one of the "stabilizations" is just high-ISO and fast shutter speeds automatically selected when there is a lot of camera movement for the focal length; more than the mechanical IS alone can combat.
-
Most likely, one of the "stabilizations" is just high-ISO and fast shutter speeds automatically selected when there is a lot of camera movement for the focal length; more than the mechanical IS alone can combat.
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=98595\")
Indeed, with a possible additional wrinkle of binning to control noise.
Olympus gives the details at [a href=\"http://www.olympus-europa.com/corporate/presscentre_presscentre.cfm?artID=41256904004CCF43AEDC67BB51548D5CC125726C006032B1]http://www.olympus-europa.com/corporate/pr...125726C006032B1[/url]
In summary, the two modes are
a. sensor shift stabilization
b. Selection of high ISO speeds (probably using "BrightCapture Technology" to control noise in exchange for reduced resolution; see below).
Some of us "serious photographers" might get snooty about it, but having auto-exposure modes that choose ISO speed in the way that they traditionally choose shutter speed and/or aperture seems a perfectly reasonable strategy to help control motion blur in "point and shoot" operation of a digital camera. It is basically a recognition of the new reality that digital cameras have three readily adjustable exposure parameters rather than just the two of a film camera.
Here is a description of BrightCapture from http://www.dpreview.com/news/0601/06012602olympus_720sw.asp (http://www.dpreview.com/news/0601/06012602olympus_720sw.asp)
BrightCapture Technology ... is also brought into play to improve picture results in certain scene modes where, as well as increasing ISO values and adjusting the shutter speed, the output of the CCD is read as Super Pixels. This means that information from every single one of the pixels on the CCD is used, but read out in blocks of nine as Super Pixels, each of which has an average reading of the nine pixels that it is comprised of. After the picture has been taken, this Super Pixel information is expanded to a higher resolution by Olympus’ TruePic algorithm. When dividing the CCD into blocks of nine pixels, an average colour and brightness reading is calculated. This ‘averaging out’ eliminates any extraneous noise within the block and makes colour gradation from one Super Pixel to the next smooth and natural.
Ignoring the interpolation to a "higher resolution", this sounds like binning to allow increased ISO to come at the cost of reduced resolution rather than increased noise.
-
In that case, it certainly is misleading to describe a choice of high ISO as 'optical image stabilisation', but not of course wrong. High shutter speeds do stabilise the image and the image is of an optical nature.
-
High shutter speeds do stabilise the image and the image is of an optical nature.
[a href=\"index.php?act=findpost&pid=98624\"][{POST_SNAPBACK}][/a]
High shutter speed does not stabilize an image. Maybe the reference is to a tripod socket.
-
In that case, it certainly is misleading to describe a choice of high ISO as 'optical image stabilisation', but not of course wrong. High shutter speeds do stabilise the image and the image is of an optical nature.
[a href=\"index.php?act=findpost&pid=98624\"][{POST_SNAPBACK}][/a]
The ccd shif is the OPTICAL stabilization, the ISO is the second non-optical stabilization, so there are 2 ie "dual" stabilizations happening, one is optical and one is not.
-
High shutter speed does not stabilize an image. Maybe the reference is to a tripod socket.
[a href=\"index.php?act=findpost&pid=98625\"][{POST_SNAPBACK}][/a]
Howie,
I've always found that, lighting conditions and high ISO performance permitting, high shutter speeds tend to stabilise the (captured) image.
-
The ccd shif is the OPTICAL stabilization, the ISO is the second non-optical stabilization, so there are 2 ie "dual" stabilizations happening, one is optical and one is not.
[a href=\"index.php?act=findpost&pid=98630\"][{POST_SNAPBACK}][/a]
As I said, this term is misleading. By 'optical image stabilisation' I understand that the lens has some shifting elements. In the context of that definition, CCD shift should not be described as 'optical image stabilisation'.
In fact it's still not clear to me what CCD shift means. This is presumably different from anti-shake where the whole sensor moves. Is it another name for 'pixel shift' which video cameras have used for years?
-
As I said, this term is misleading. By 'optical image stabilisation' I understand that the lens has some shifting elements.
[a href=\"index.php?act=findpost&pid=98661\"][{POST_SNAPBACK}][/a]
Ray, you may understand "optical image stabilization" to mean doing it the way that you arwe familiar with from your Canon SLR system, but there is nothing in the combination of words that implies movement of one part of the optical system (lens elements) rather than another (sensor).
Practically, the result is about the same: the image of a particular part of the scene continues to fall on the same part of the sensor throughout the exposure time despite camera movements, reducing blurring due to camera motion at a given shutter speed. And this is essentially different from other approaches to reducing camera motion blur, which require higher shutter speeds, higher ISO, fixing the camera in place with a tripod etc.
Perhaps it would be useful for us to concentrate on the facts (like how the pictures look in the end) and stop worrying or debating so much about what is the right and wrong way to use words like "optical stabilization", "enlargement", "lens speed" or "sensor speed". Or even "depth of field".
-
Ray, you may understand "optical image stabilization" to mean doing it the way that you arwe familiar with from your Canon SLR system, but there is nothing in the combination of words that implies movement of one part of the optical system (lens elements) rather than another (sensor).
[a href=\"index.php?act=findpost&pid=98715\"][{POST_SNAPBACK}][/a]
Quite true, and I said as much on the previous page. I don't think anyone could take Olympus to court for using a phrase outside of any generally more accepted meaning, but still within the fundamental meaning of the words.
Nevertheless, when companies do use expressions in this manner, outside of their usual meaning, some confusion inevitably results. Doing a quick Google search on Optical Image Stabilization I came across the following distinction made with respect to the use of these terms with video cameras.
What's EIS/DIS?
Electronic Image Stabilization and Digital Image Stabilization are completely electronic means for correcting image shake. As the shaky image hits the CCD chip, these systems reposition the active area of the chip (the location on the chip that the image is read from) to compensate for it, by re-addressing the area of the chip that they're reading from. If you've seen Rocky & Bullwinkle (a US cartoon involving a moose and a squirrel), think of Bullwinkle running back and forth with the bucket of water to catch Rocky after Rocky jumps from the high diving board (of course, Bullwinkle winds up in the water, but that's another story).
The EIS/DIS controllers look for motion vectors in the image (typically a widespread displacement of the entire image) and then decide how to "reposition" the image area of the chip under the image to catch it in the same place. The actual repositioning is done in one of two ways: one is to enlarge (zoom) the image digitally, so that the full raster of the chip isn't used. The controller can then "pan and scan" within the full chip raster to catch the image as it moves about. The other is to use an oversize CCD, so that there are unused borders that the active area can be moved around in without first zooming the image.
The zoom-style pan 'n' scanner can be detected quite simply: if the image zooms in a bit when EIS/DIS is turned on, then a zoom-style pan 'n' scanner is being used. Unfortunately, such methods reduce resolution, often unacceptably.
All EIS/DIS systems suffer from several problems. One is that, because the actual image is moving across the face of the chip, image shakes induce motion blur. Even though the position of an image may be perfectly stabilized, you can often notice a transient blurring of the image along the direction of the shake. Sometimes it's quite noticeable. To get around this, many EIS/DIS systems close down the shutter a bit to reduce blur. This reduces light gathering capability. You can't have everything, you know.
Another problem is that the motion-vector approach to stabilization can be easily fooled. If the area of the image being scanned doesn't have any contrasty detail that the processor can lock onto, the stabilization can hunt, oscillate, or bounce. This looks like a mini-earthquake on the tape, and it can occur at the most annoying times.
Also, the stabilization can work too well. Often when one starts a slow pan or tilt with EIS/DIS engaged, the system will see the start of the move as a shake, and compensate for it! Eventually, of course, the stabilizer "runs out of chip" and resets, and the image abruptly recenters itself.
The big advantage of EIS/DIS is that it's cheap.
What's optical stabilization?
Optical stabilization such as "SteadyShot" is descended from Juan de la Cierva's 1962 Dynalens design, a servo-controlled fluid prism used to steer the image before it hits the CCDs (in the '60s, of course, it steered images onto film or onto tubes!). In the late '80's and early '90's, Canon and Sony updated this technology for use in consumer gear, and it worked so well that Canon now offers a SteadyShot attachment for some of their pro/broadcast lenses.
The fluid prism is constructed of a pair of glass plates surrounded by a bellows and filled with fluid so that the entire assembly has a refractive index comparable to a glass prism. The angle of the prism is changed by tilting the plates; one plate can be rotated vertically, moving the image up or down, and the other rotates horizontally, steering the picture right or left.
Rotation rate sensors detect shake frequencies and tilt the front and back plates appropriately. Position sensors are also used so that in the absence of motion the prism naturally centers. The position sensors also detect when the prism is about to hit its limit stops, and reduce the corrections applied so that shake gradually enters the image instead of banging in as the prism hits its limits.
Optical stabilization of this sort is expensive, tricky to manufacture and calibrate, and must be tuned to the lens. Adding a wide-angle or telephoto adapter to a SteadyShot lens screws up SteadyShot; the processor doesn't know about the changed angle of view (all it knows is the current zoom setting) and thus over- or under-compensates for shake.
But for all that it works brilliantly: because the image is stabilized on the face of the CCDs, there is no motion blur; because rate sensors are used, the system isn't fooled by motion in the scene or by lack of detail; because a physical system has to move to reposition the image, there are no instantaneous image bounces or resets as can happen with EIS/DIS.
[It's interesting to note that on the XL-1, Canon added image motion-vector detection to the rate gyros on their optical stabilizer. As a result, the system seems to "stick" on slow pans and tilts just like an EIS/DIS system, although the recovery is more fluid and less jarring. On the other hand, it really does a superb job on handheld lockdowns.]
-
I don't think anyone could take Olympus to court for using a phrase outside of any generally more accepted meaning, but still within the fundamental meaning of the words.
[a href=\"index.php?act=findpost&pid=98778\"][{POST_SNAPBACK}][/a]
Your evidence for lens-based as the "generally more accepted meaning" of optical stabilization is really just evidence that this is the oldest and more widely used version, for the obvious reason that it is the only version that was usable with film. Taking the oldest or more common example of something to be the best or only correct version is a fallacy (I am tempted to say, very conservative or even reactionary thinking!) A bit like ideas that one particular aspect ratio or frame size common in the film era is inherently the best or correct one under all circumstances.
-
A bit like ideas that one particular aspect ratio or frame size common in the film era is inherently the best or correct one under all circumstances.
[a href=\"index.php?act=findpost&pid=98904\"][{POST_SNAPBACK}][/a]
Surely you wouldn't accuse me of that degree of narrow-mindedness, BJL, after all the discussions we've have on the topic of aspect ratios .
The only issue I have with this apparent abuse of terminology (by Olympus and others) is that the negative aspects of one form of image stabilisation compared with another, might be glossed over.
I get the impression that the 'pixel shifting' approach can reduce over-all resolution. I certainly got this impression when I first used a Panasonic videocam, which I foolishly bought some years ago because it was on special and boasted broadcast quality. I was so disappointed in the resolution and dynamic range, I never used it again after the first few weeks.
-
I get the impression that the 'pixel shifting' approach can reduce over-all resolution.
You're confusing electronic stabilization, where a smaller area of the sensor is used and the "crop area" is moved around via bit-fiddling, versus Olympus' optical stabilization, which physically moves the entire sensor chip around, and has no resolution penalty.
-
Wonder if somebody could hack a RAW option?
JC
[a href=\"index.php?act=findpost&pid=97599\"][{POST_SNAPBACK}][/a]
Exactly. Surely the RAW function is purely a matter of firmware? Presumably Canon could issue an update to add RAW if they wanted to? Any point in leaning on them?
Pete
-
You're confusing electronic stabilization, where a smaller area of the sensor is used and the "crop area" is moved around via bit-fiddling, versus Olympus' optical stabilization, which physically moves the entire sensor chip around, and has no resolution penalty.
[a href=\"index.php?act=findpost&pid=98984\"][{POST_SNAPBACK}][/a]
Exactly my point, Jonathan. Even I'm confused, and that can't be good. .
I get the impression from the 'dcresource' preview that the SP-550 actually employs 3 types of image stabilisation; the sensor shift, the high ISO/big aperture approach and 'pixel shifting' for video mode.
-
Panasonic are now offering RAW on an established digicam which sport harware vibration reduction.
http://luminous-landscape.com/forum/index....showtopic=14577 (http://luminous-landscape.com/forum/index.php?showtopic=14577)
-
The only issue I have with this apparent abuse of terminology (by Olympus and others) is that the negative aspects of one form of image stabilisation compared with another, might be glossed over.
I get the impression that the 'pixel shifting' approach can reduce over-all resolution.
[a href=\"index.php?act=findpost&pid=98951\"][{POST_SNAPBACK}][/a]
If people are indeed subject to confusions (like you confounding of pixel shift post-procxeesing so physically moving the sensor), the solution surely is to look at results, not buzz-words.
At least read reviews of how a particular camera handles low shutter speed hand-holding, or better yet test it oneself. I suggest a double espresso first, to intensify the challenge to the technology.
-
If people are indeed subject to confusions (like you confounding of pixel shift post-procxeesing so physically moving the sensor), the solution surely is to look at results, not buzz-words.
[a href=\"index.php?act=findpost&pid=99465\"][{POST_SNAPBACK}][/a]
Absolutely, and I shall look forward to viewing comparisons between the the SP-550 at 500mm equiv focal length and model XX-xxx at 500mm which employs true 'lens shift' optical image stabilisation.
-
... true 'lens shift' optical image stabilisation.
[a href=\"index.php?act=findpost&pid=99516\"][{POST_SNAPBACK}][/a]
where by "true", you mean little more than "the type that I am familiar with, and which used to be the only type since it was the only type that worked with film"? You have totally failed to show that physically moving the back end of the optical system (the sensor) is any more or less "truly optical" than moving parts further forward (lens elements), so why are you persist in declaring that any other approach is "false"?
-
You have totally failed to show that physically moving the back end of the optical system (the sensor) is any more or less "truly optical" than moving parts further forward (lens elements), so why are you persist in declaring that any other approach is "false"?
[a href=\"index.php?act=findpost&pid=99648\"][{POST_SNAPBACK}][/a]
I don't have the means to 'show'. All I can do is draw inferences from the discussions I see on the net. With long telephoto lenses, lens shift appears to be more effective than sensor shift. Is this not the case?
-
I don't have the means to 'show'. All I can do is draw inferences from the discussions I see on the net. With long telephoto lenses, lens shift appears to be more effective than sensor shift. Is this not the case?
[a href=\"index.php?act=findpost&pid=99654\"][{POST_SNAPBACK}][/a]
Ray, you have completely ducked the point. I was not discussing which works better, I am discussing you unjustified use of the wording "real optical stabilization" to apply only to lens wiggling and not sensor wiggling.
But as to those discussions about how well the different methods work with long lenses, I find them seriously lacking in quantitative basis. All they seem to show is that sensor wiggling might require grater sensor movements for longer focal lengths, but that gives no comparison to how well it compares to lens wiggling.
More important, it is the real focal length that matters, not the "35mm equivalent".
If you need enough sensor movement to keep up with camera movement before the exposure starts as well as during, the amount of movement needed (in mm) depends on the actual focal length, independent of the format. This is because a given angular twist of the cameras moves the image relative to the sensor by about (focal length)/(angle). In the Olympus digicam under discussion, the maximum true focal length is about 80mm, small relative to the focal lengths of interest in Sony and Pentax sensor stabilized cameras. (And I expect compact digicam lenses to stay under about 100mm.)
Sensor based stabilization might struggle with real 500mm lenses.
Life is even easier with "just in time" stabilization that is only active during exposure, not during composition. My estimate is that
1. Without stabilization, decent sharpness needs the image motion across the sensor during exposure to be 1/1000th or less of the sensor width, and a smaller fraction for higher resolution needs: maybe no more than about two pixel widths.
2 This presumably happens at traditional hand-holdable shutter speeds.
3. To get four stops of stabilization requires handling 16 times that traditional hand-holdable shutter speed, a situation where without stabilization the image might move as much as 16/1000's of the way across the sensor, but not more than about that.
4. So sensor moving stabilization only needs that much sensor movement during the exposure. For a compact digicam sensor, this means less than 0.2mm of movement. For a 35mm format sensor, it would mean less than 0.5mm.
And for any format, the amount of sensor movement needed during exposure does not depend on focal length or angular field of view! It depends only on how many stops you want to go beyond the hand-holdable limit.
-
Ray, you have completely ducked the point. I was not discussing which works better, I am discussing you unjustified use of the wording "real optical stabilization" to apply only to lens wiggling and not sensor wiggling.
If lens shift as opposed to sensor shift does not have any inherent advantage, then it really does not make any difference which terminology is used. The only issue I see here is the possibility that consumers might be misled into believing they are getting a better image stabilisation system than they actually are getting in practice.
More important, it is the real focal length that matters, not the "35mm equivalent".
If you need enough sensor movement to keep up with camera movement before the exposure starts as well as during, the amount of movement needed (in mm) depends on the actual focal length, independent of the format. This is because a given angular twist of the cameras moves the image relative to the sensor by about (focal length)/(angle). In the Olympus digicam under discussion, the maximum true focal length is about 80mm, small relative to the focal lengths of interest in Sony and Pentax sensor stabilized cameras. (And I expect compact digicam lenses to stay under about 100mm.)
I find it difficult to reconcile this statement with the 1/35FL rule for a reasonably sharp hand-held shot enlarged to 8x10" print size. You are not suggesting, are you, that without image stabilisation, sharp images are possible using 1/7th sec exposure with the average P&S using a 'standard' focal length?
-
If lens shift as opposed to sensor shift does not have any inherent advantage, then it really does not make any difference which terminology is used.
[a href=\"index.php?act=findpost&pid=99740\"][{POST_SNAPBACK}][/a]
Perhaps we should leave it at that, instead of using prejudical wordings like "real optical image stabilization".
find it difficult to reconcile this statement with the 1/35FL rule for a reasonably sharp hand-held shot enlarged to 8x10" print size. You are not suggesting, are you, that without image stabilisation, sharp images are possible using 1/7th sec exposure with the average P&S using a 'standard' focal length?
[a href=\"index.php?act=findpost&pid=99740\"][{POST_SNAPBACK}][/a]
Be careful to distinguish absolute distance that the image moves (in mm) from angular distance or the number of pixels that the image moves across, which is more in line with how much blur one would get without stabilization. Angular movement, or pixels of movement, depends on the angular FOV of the lens, and so depends roughly on "35mm format equivalent focal lengths", but actual distance moved depends mainly on "true focal length". Of course, the same distance of image movement will cause different amount of image blurring in different formats due to the different degree of enlargement needed to get the same sized print.
The reason I estimated movement distance (in mm) was to estimate how much sensor movement is needed to compensate for it. It seems to be that the physical limitation on sensor stabilization (do you approve this wording?) is mostly how much sensor movement is needed. With smaller sensors perhaps having the advantage of lower weight, so that moving over equal distance requires less forces and energy, while large sensors and pixels having the advantage that the movements can be less precise.
By the way, several reviews of Panasonic's OIS lens stabilization indicate that it achieves somewhat better image quality in "mode 2", where stabilization is done only during the exposure, than in "mode 1", where stabilization operates also during composition (so also stabilizing the VF image.) Maybe because in mode 2, exposure starts with the stabilizing elements waiting in the optimal central position, rather than risking already being pushed to the limits of their movement during wobbly composition as could happen in mode 1. If so, the same could apply to leaving the sensor in central position until the shutter release starts.
An experiment I did: with my narrowest FOV lens, 200mm in 4/3" format, I see the VF image move around by about 1/10th of the frame width, which means about 2mm across the frame (which is 18mm wide), so about 1/100th of the focal length. I propose as a cautious rule that "mode 1" sensor stabilization that operates during composition probably needs to be be able to move the sensor about 1/50th of the focal length. That is only a couple of mm for "super-zoom" digicams with their sub-100mm maximum focal lengths, but maybe up to a cm or so with super-telephoto SLR lenses at 400mm and up.
-
BJL,
Maybe this all boils down to one type of image stabilisation technology being more practical to implement in a particular type of camera design, perhaps sensor shift being more suitable for the smaller camera and lens shift more suitable for the larger camera.
I notice that Canon are claiming a 3 stop advantage with their new 70-200L F4 IS, as they do with the 24-105 IS. Building image stabilisation into the lens, allows for improvements without upgrading the whole camera. This wouldn't be a concern with a P&S camera.
Doing a bit of Googling on the subject, I notice that some photographers take multiple shots in continuous mode when trying to get a sharp shot with IS and slow shutter speeds. It seems to be often the case that, whilst most of the shots might be substandard with regard to sharpness, the odd one or two might be very acceptably sharp.
I'll try employing this technique. I have noticed that 1/13th exposure with my 24-105mm IS at 24mm (using the 5D) is a bit risky and 1/6th even more so, yet a 3 stop advantage would convert 1/6th sec into the equivalent of 1/50th, which should be fast enough for 24mm.
-
BJL,
Maybe this all boils down to one type of image stabilisation technology being more practical to implement in a particular type of camera design, perhaps sensor shift being more suitable for the smaller camera and lens shift more suitable for the larger camera.
I notice that Canon are claiming a 3 stop advantage with their new 70-200L F4 IS, as they do with the 24-105 IS. Building image stabilisation into the lens, allows for improvements without upgrading the whole camera. This wouldn't be a concern with a P&S camera.
Doing a bit of Googling on the subject, I notice that some photographers take multiple shots in continuous mode when trying to get a sharp shot with IS and slow shutter speeds. It seems to be often the case that, whilst most of the shots might be substandard with regard to sharpness, the odd one or two might be very acceptably sharp.
I'll try employing this technique. I have noticed that 1/13th exposure with my 24-105mm IS at 24mm (using the 5D) is a bit risky and 1/6th even more so, yet a 3 stop advantage would convert 1/6th sec into the equivalent of 1/50th, which should be fast enough for 24mm.
[a href=\"index.php?act=findpost&pid=99946\"][{POST_SNAPBACK}][/a]
OPINION
It may be that Canon uses IS in the lens, not as a practicle measure, but with a mind toward backfitting IS to older camera bodies. Perhaps similar to autofocus motors in the lens instead of the body.
-
OPINION
It may be that Canon uses IS in the lens, not as a practicle measure, but with a mind toward backfitting IS to older camera bodies. Perhaps similar to autofocus motors in the lens instead of the body.
[a href=\"index.php?act=findpost&pid=99949\"][{POST_SNAPBACK}][/a]
No, Howard. There's no compatibility between Canon's newer autofocus, IS lenses and older pre-autofocus bodies, just as there's no compatibility between the older Canon FD lenses and the newer bodies supporting autofocus.
This has always been considered a disadvantage of the Canon system in relation to a Nikon system which allows the use of older lenses, even though autofocus is disabled.
-
BJL,
Maybe this all boils down to one type of image stabilisation technology being more practical to implement in a particular type of camera design, perhaps sensor shift being more suitable for the smaller camera and lens shift more suitable for the larger camera.
[a href=\"index.php?act=findpost&pid=99946\"][{POST_SNAPBACK}][/a]
Maybe so.
Building image stabilisation into the lens, allows for improvements without upgrading the whole camera.
[a href=\"index.php?act=findpost&pid=99946\"][{POST_SNAPBACK}][/a]
That cuts both ways:
- to get the newest lens-based stabilization, replace each lens that you want stabilized, use existing bodies,
- to get the newest sensor-base stabilization, replace each body (one for most of us) and use all existing lenses with stabilization.
By the way, I am with Howard on the idea that for Canon and Nikon, lens-based stabilization has some advantage of backward compatibility with many SLR's already in use, film and digital. This compatibility goes back about twenty years for Canon, even if it fails with truly ancient pre-EOS bodies. But it could also be simply that they already have good lens-based stabilization technology, and so have less incentive to invest in developing a different one, like sensor-based. (A bit like designing DSLR's for at least partial and transitional compatibility with their substantial lens systems.)
-
That cuts both ways:
- to get the newest lens-based stabilization, replace each lens that you want stabilized, use existing bodies,
- to get the newest sensor-base stabilization, replace each body (one for most of us) and use all existing lenses with stabilization.
Right! It does cut both ways. In fact, in the absence of any inherent superiority of one system over the other, sensor based stabilisation is more efficient since it applies to all lenses that fit the camera. Since camera bodies are developing and improving at a faster rate than lenses, there's more potential perhaps to lever a greater all-round improvement simply by making a body with a better anti-shake sensor, especially in situations where the total value of all one's lenses is far greater than the cost of the latest body.
I guess one can't have everything . I recall when I upgraded from my D60 to a 20D, I felt I had acquired at least a 2 stop image stabilisation advantage for all my lenses, since performance at ISO 1600 with the 20D is at least as good as ISO 400 on the D60. In fact, it was better than a mere 2 stop advantage because higher ISO also allows the opportunity to prevent motion blur in the subject.
If Canon had previously adopted a sensor-based image stabilisation system and had been able to provide an additional stop of IS in the 20D body as well as much improved performance at high ISO, then that would have been just super .
Which brings me back to Howard's suggestion that Canon's reason for choosing lens shift IS as opposed to sensor-shift IS is perhaps a means of ensuring backwards compaitibility to older bodies. How can this be? It's another of 'Howie opinions' that doesn't make sense to me. The Canon lens-based IS system was born in the days of film, long before Canon released it's first DSLR, the D30. I had actually switched from Minolta to Canon primarily because of Canon's IS system before I had an inkling that Canon was soon to release a 3mp DSLR. Howard as an engineer should appreciate that an anti-shake film based system would not have been an option.
The only good reason I can now see for Canon to switch to a sensor-based IS system (for its DSLRs) is if it were possible to provide an improvement over the lens-shift system. If Canon were to come out with a camera body that offered such improvement, there could hardly be any complaint from people who already own IS lenses. They would simply switch off the IS function in their IS lenses and enjoy the improved results from the camera body's internal IS.
-
I don't see how a sensor-shift IS system would work well with really long lenses (400mm on up). The sensor would have to move a pretty large fraction of its size quite fast to be effective. I think jiggling a lens element a few mm in the lens somewhere is a more advantageous approach, as it can work on a lens of any focal length.
-
I don't see how a sensor-shift IS system would work well with really long lenses (400mm on up). The sensor would have to move a pretty large fraction of its size quite fast to be effective.
[a href=\"index.php?act=findpost&pid=100832\"][{POST_SNAPBACK}][/a]
You may be right, but I am not sure, as I hinted in my earlier posts. (Remember the camera that started this is a digicam with maximum focal length of about 80mm.)
A summary of my earlier calculations.
1) If sensor stabilization is active during composition as well as during exposure, it might need up to 1cm or more of movement with 400mm, which might be difficult. However, if I remember right, Konica-Minolta said that its DSLR sensor stabilization system had over 1cm of movement. (I would not worry much about the sensor moving out of the image circle: super-telephoto lenses typically project an image circle distinctly larger than needed, and certainly can be designed that way at no additional cost if needed for optimal stabilization performance.)
2) If stabilization is activated only as shutter release starts (as in one mode of Panasonic OIS), long lenses are probably not a problem, as sensor movement only has to keep up with camera movement during the exposure time, plus a bit of "getting up to speed" time. To get about four stops of improvement over un-stabilized performance (16 times the shutter speed) the sensor movement needed during the actual exposure is no more than sixteen times the tolerable amount of image movement across the sensor in un-stabilized operation. Estimating the latter to be at most 1/1000th of sensor width, the sensor needs to move no more than 16/1000ths of sensor width during the exposure to get four stops of stabilization, regardless of focal length.
How much "up to speed" time is needed, and how much more movement does this require? It seems likely that a stabilization system need to handle changes in direction of camera movement within the exposure time, so it must have a "reaction time" no greater than exposure time. If so, the up to speed time would not need to be more than the exposure time. So double the time that the sensor needs to be in movement, and double the needed movement to about 32/1000ths of sensor width; only about 1mm for four stops in 35mm format.
-
Ray and Jonathan in particular,
what about the following dual stabilization approach for DSLR's?
- Some stabilized lenses, particularly at longer focal lengths where this technology might be the best option.
- Sensor stabilization working with all other lenses, including ones like wide angles where stabilization can occasionally be useful, but stabilized lenses are unlikely to be offered.
- Only one system used at as time, unless clever coordination can be worked out.
Pentax and Sony in effect have this dual option to a small extent, due to Sigma's stabilized OS lenses [correction: Sigma's only OS lens so far is not yet available in Pentax or Sony mount], and I am guessing that the FourThirds system will also have this soon, via Panasonic OIS lenses and new Olympus bodies.
-
Ray and Jonathan in particular,
what about the following dual stabilization approach for DSLR's?
- Some stabilized lenses, particularly at longer focal lengths where this technology might be the best option.
- Sensor stabilization working with all other lenses, including ones like wide angles where stabilization can occasionally be useful, but stabilized lenses are unlikely to be offered.
[a href=\"index.php?act=findpost&pid=100893\"][{POST_SNAPBACK}][/a]
I'm all for that approach. One of my most used lenses is the Sigma 15-30 with no IS. Since I try to use exposures that are at least 1/FL with IS switched on, (which is often possible with good lighting even at f11 and ISO 100, and if not, an increase in ISO fixes that), I should by the same standards be using 1/4FL with my Sigma 15-30. I'm afraid for some reason I don't keep to those same standards.
However, whilst this idea of a dual image stabilisation approach would be very attractive for the consumer, I think Canon would be reluctant to implement it because it might give a competitive edge to other lens manufacturers, such as Sigma. There would be many owners of a Canon DSLR system who would have considered the purchase of a cheaper third-party lens, having read perhaps it is optically on a par with the more expensive Canon equivalent, but have finally been dissuaded from such a purchase due to the lens not having image stabilisation. In situations where the more expensive Canon lens has IS and the cheaper 3rd party equivalent doesn't although it's optically as good, it's almost a no-brainer as to which lens to get, unless you are one of those who always uses a tripod.
-
I didn't know what was the appropriate forum for this, but since Michael reviewed the G7 and there was a long discussion about the missing RAW on this one, I post it here...
The Askey forum has a news note on a new Olympus P&S, the SP550, which has an 18x (!!!) zoom lens -- 35mm equivalent of 28-504 -- with image stabilization, which it probably desperately needs at the long end. Anyway, the length of the zoom made me laugh. Other stuff is pretty interesting: 7.1 mp chip, which meant that they stayed clear of the MP race, and some of the 7 mp chips have been really good. Also, it has RAW. If the high ISO capability is there, and it could be (has settings for ISO 50-5000) with the slightly larger pixels of the 7mp chip, and if the glass is up to Olympus' higher standards...it could be a contender.
On the downside: electronic view finder.
JC
[a href=\"index.php?act=findpost&pid=97518\"][{POST_SNAPBACK}][/a]
There are a lot of High Zoom Electronic Viewfinder cameras that shoot RAW. Most of them look like a DSLR but are just a bit smaller and less expensive. They do have their advantages, but they are NOT pocket sized. Panasonic Lumix and Leica seem to be the only pocket sized cameras I know of that shoot RAW. However, "Word on the street" is that these models have noisy sensors.
If anyone knows of a widely available pocket sized camera with up to date features and which shoots RAW, I would love to know about it, but I have looked a lot and not found one, other than Panasonic and Leica. (Which I won't buy).
In the interim I plan to get a Fuji S30d for about $300 or maybe $350 and wait for the ideal camera to come along. There is one other option I have Found: Fuji E-900. It shoots RAW at 9 MP and has a 2" LCD on the back. menus on the screen are similar to Canon pull down style on the digital rebel series - which is not as appealing as the Nikon P&S use. In th eideal world, Fuji would add a 3" screen + a viewfinder and clean up the user interface, but its probably a good camera.
Anybody who has experince with these models would be really good to hear from, but the best advice from members is always welcome.