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#21
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Image Stabilization vs Noise
jpc wrote:
On Thu, 21 Dec 2006 10:44:48 -0800, Phil Wheeler wrote: jpc wrote: Based on some published information from a review site, IS point and shoot camera seem to be more noisy than non IS camera. This I'm blaiming on electrical pickup from the piezo motors used to move either a lens element or the sensor. Anyone have any experience or comments on this topic It would help if you provided a link to the review site. Yesterday was a busy day, so I didn't get a change to get back to anyone's post. The review site I'm using is imaging-resource.com. While I believe they mentioned high noise in a review of a Canon IS P&S, what I've done is use the DaveBox images to do my own noise analysis. If you take the trouble to extract the information, these images are a treasure trove of information on camera performance since the imaging-resource people have been taking pictures of the same target under the same lighting conditions for the last 12 years. Here is my procedure if you want to duplicate the data I have on my screen right now. Go to the Canon 5D, Canon S3IS and Oly SP350 reviews. Download the 200 and 400 ISO low light (11lumen) davebox images of all three cameras. These are at the end of the review and are the one's I've been using since 11 lumens is roughly the light level you'd see at night on a lighed city street. Next Google ImageJ and go to the NIH website for a free download. ImageJ is an excellent image analysis package that will do many things but the only thing you have to do is hit the line icon on the tool bar and drag a line down the grey scale section on the right central part of your davebox images. Then hit Cnrl-K and a staircase graph will pop up. You'll see the value (0-255) for each step in the grey scale with the noise superimposed on the steps. The Canon5D is our standard. Notice how all the noise is low and all the steps are easily seen. (The bumpiness near the bottom is a target problem). Also notice how the noise stays constant. Next look at at SP350 graph--one of the tiny pixel (5 square microns) camera that many in the news group like to trash. It's noise is 3 time worse than the 5D, which is exactly what you'd expect since the sensor area is 9 times smaller. And like the 5D the noise is pretty much constant as you move down the graph Now look at the S3IS graph. Not only is the noise not even close to being constant, it's over 10 time worse than the 5D in the dark area of the grey scale and 3-4 times worse that the SP350. Note--I'd argue that since ISO numbers are just gain settings to compare the sensor noise in cameras, you should start at lowest and X1 gain-- no matter what the marketing folks decided to call that setting -- and count up gain steps. So my numbers are from comparing the 200 ISO graphs of the 5D and Sp350 (both cameras start at ISO50) with the 400 ISO of the S3IS. If you disagree and compare graphs labeled with the same ISO numbers, the results are the same, just a little less obvious. So what going on? Since Canon does know how to make good low noise cameras, I'm guessing the problem is caused by electrical pickup from the piezo motors. With the sensor ouputs measured in microvolts and the piezo motors being hit continiously at much higher voltages the design must be a noise-engineer's nightmare. What you're seeing has absolutely nothing whatever to do with IS. It has to do with the sensor size, type, and the signal amplificatino required to eek data out of much smaller sensor points. The full frame on the 5D has comparatively HUGE points, which are naturally capable of gathering more light...meaning less need to amplify the signal. This is one of many reasons why small sensor point-and-shoots can't compete with DSLRs in terms of noise adn high ISO performance. Again... NOT an IS issue. I have three IS cameras and four IS lenses for my DSLR. None of these types of noise has been an issue. I wouldn't expect to see this on a DSLR using IS lens since the piezo motors are much farther away from the sensor electronics. Any comments? jpc -- Images (Plus Snaps & Grabs) by Mark² at: www.pbase.com/markuson |
#22
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Image Stabilization vs Noise
Skip wrote:
"jpc" wrote in message ... Based on some published information from a review site, IS point and shoot camera seem to be more noisy than non IS camera. This I'm blaiming on electrical pickup from the piezo motors used to move either a lens element or the sensor. Anyone have any experience or comments on this topic jpc I'm guessing it's because the p&s IS cameras have "digital" stabilization, which, in many cases, is merely a bump up for ISO and shutter speed, which, of course, results in more noise... If he's talking about non-optical IS, then that's a different story altogether, and has little or no relation to optical IS lenses attached to DSLRs... -- Images (Plus Snaps & Grabs) by Mark² at: www.pbase.com/markuson |
#23
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Image Stabilization vs Noise
On 22 Dec 2006 12:46:57 -0800, DougL wrote:
We spend several days and a lot of words trying to establish exactly who has what. As far as the thread participants were concerned, we ended up concluding that point and shoot cameras did NOT have OIS. Can you supply a pointer that says otherwise? Would be interesting to know who really does image stabilization (either CCD-shift or optical) in a point-and-shoot. Yes, "moving mirror" was my shorthand. "Moving optic" would have been more accurate. After a brief search, the cheapest camera I could find with a real optical stabilizer (using a lens-shift system) is the Panasonic LZ3, $160 at B&H. Plenty of other P&Ss, from a whole slew of makers, use real mechanical stabilizers. -dms |
#24
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Image Stabilization vs Noise
On 22 Dec 2006 12:53:21 -0800, DougL wrote:
As I said, these inexpensive cameras just have DIS, and there isn't anything moving in this "stabiliztion system". Not even electrons between pixels. Go to http://www.dpreview.com/reviews/panasoniclz2/page5.asp and look at the sample images on that page. It's a real lens-shift stabilizer. This year's version of the same camera goes for about $150ish, which definitely puts it in the 'inexpensive' category. Never heard of moving the sensor. As in moving the CCD? Engineering-wise, that would be pretty challenging. The stabilizer system that Sony inherited from Minolta is a sensor-shift system, as is the stabilizer that Pentax uses in their DSLRs. -dms |
#25
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Image Stabilization vs Noise
On Sat, 23 Dec 2006 01:50:14 -0800, "Mark²" mjmorgan(lowest even
number wrote: jpc wrote: On Thu, 21 Dec 2006 10:44:48 -0800, Phil Wheeler wrote: jpc wrote: Based on some published information from a review site, IS point and shoot camera seem to be more noisy than non IS camera. This I'm blaiming on electrical pickup from the piezo motors used to move either a lens element or the sensor. Anyone have any experience or comments on this topic It would help if you provided a link to the review site. Yesterday was a busy day, so I didn't get a change to get back to anyone's post. The review site I'm using is imaging-resource.com. While I believe they mentioned high noise in a review of a Canon IS P&S, what I've done is use the DaveBox images to do my own noise analysis. If you take the trouble to extract the information, these images are a treasure trove of information on camera performance since the imaging-resource people have been taking pictures of the same target under the same lighting conditions for the last 12 years. Here is my procedure if you want to duplicate the data I have on my screen right now. Go to the Canon 5D, Canon S3IS and Oly SP350 reviews. Download the 200 and 400 ISO low light (11lumen) davebox images of all three cameras. These are at the end of the review and are the one's I've been using since 11 lumens is roughly the light level you'd see at night on a lighed city street. Next Google ImageJ and go to the NIH website for a free download. ImageJ is an excellent image analysis package that will do many things but the only thing you have to do is hit the line icon on the tool bar and drag a line down the grey scale section on the right central part of your davebox images. Then hit Cnrl-K and a staircase graph will pop up. You'll see the value (0-255) for each step in the grey scale with the noise superimposed on the steps. The Canon5D is our standard. Notice how all the noise is low and all the steps are easily seen. (The bumpiness near the bottom is a target problem). Also notice how the noise stays constant. Next look at at SP350 graph--one of the tiny pixel (5 square microns) camera that many in the news group like to trash. It's noise is 3 time worse than the 5D, which is exactly what you'd expect since the sensor area is 9 times smaller. And like the 5D the noise is pretty much constant as you move down the graph Now look at the S3IS graph. Not only is the noise not even close to being constant, it's over 10 time worse than the 5D in the dark area of the grey scale and 3-4 times worse that the SP350. Note--I'd argue that since ISO numbers are just gain settings to compare the sensor noise in cameras, you should start at lowest and X1 gain-- no matter what the marketing folks decided to call that setting -- and count up gain steps. So my numbers are from comparing the 200 ISO graphs of the 5D and Sp350 (both cameras start at ISO50) with the 400 ISO of the S3IS. If you disagree and compare graphs labeled with the same ISO numbers, the results are the same, just a little less obvious. So what going on? Since Canon does know how to make good low noise cameras, I'm guessing the problem is caused by electrical pickup from the piezo motors. With the sensor ouputs measured in microvolts and the piezo motors being hit continiously at much higher voltages the design must be a noise-engineer's nightmare. What you're seeing has absolutely nothing whatever to do with IS. It has to do with the sensor size, type, and the signal amplificatino required to eek data out of much smaller sensor points. The full frame on the 5D has comparatively HUGE points, which are naturally capable of gathering more light...meaning less need to amplify the signal. As I stated in my follow-up post to David Taylor the 5D has a pixel size of ~70 sq microns and an active sensor size of ~45 sq microns. The Oly SP350--a much underrated camerra I ended up buying--has an active sensor size of ~5 sq microns. Photon shot noise, Poison noise, or the random way Momma Nature tosses light into your lens is "roughly" determined by pixel size. The real parameter is pixel well depth--something the camera manufactures have decided not to tell us about. Since Momma Nature noise is determined by the sq root of the number of photo electrons collected and the square root of 9 is 3, the SP350 has a S/N 3 time worse than the 5D in the regions where Momma Nature noise dominates. This is what theory predicts, this is what the data from Imaging- resourse shows and most important to me--this is how the SP350 I bought performed when I tested it. So I've lost a stop and a half of signal to noise by buying a camera that some in this group automatically trash .But since I paid 20X less that a 5D with lens the price /performance ratio is definately in my favor. And of couse, I can carry around my camera outfit--camera, batteries, cards, telephoto and wide angle extender lens, even a mini tripod-- in my coat pocket. That's something you can not say about a 5D and its collection of lens. This is one of many reasons why small sensor point-and-shoots can't compete with DSLRs in terms of noise adn high ISO performance. Again... NOT an IS issue. The Imaging-resouce noise data for the S3IS does NOT follow the theory and physics of Momma Nature noise. The noise in the dark patches--the shadow areas in low light photography where S/N is most important-- is 4 X worse than it should be. From that I can draw two conclusions. The first is that image stabization in a high end P&S is not the solution to all problems like the camera sellers want you to believe when you plop down your $400. The second is that the S3IS is overall a lousy camera. So if anyone who own a IS P&S is willing to spend a couple hours of their life to help answer this burning question, I'm willing to offer advice and comentary. If I'm wrong, I'm wrong. But if I'm right, 2 bucks worth of chain vs 400 bucks worth of camera makes for an excelent price/perfomance ratio jpc |
#26
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Image Stabilization vs Noise
"jpc" wrote: As I stated in my follow-up post to David Taylor the 5D has a pixel size of ~70 sq microns and an active sensor size of ~45 sq microns. The Oly SP350--a much underrated camerra I ended up buying--has an active sensor size of ~5 sq microns. Photon shot noise, Poison noise, or the random way Momma Nature tosses light into your lens is "roughly" determined by pixel size. The real parameter is pixel well depth--something the camera manufactures have decided not to tell us about. Since Momma Nature noise is determined by the sq root of the number of photo electrons collected and the square root of 9 is 3, the SP350 has a S/N 3 time worse than the 5D in the regions where Momma Nature noise dominates. This is what theory predicts, this is what the data from Imaging- resourse shows and most important to me--this is how the SP350 I bought performed when I tested it. So far so good, but... So I've lost a stop and a half of signal to noise by buying a camera that some in this group automatically trash .But since I paid 20X less that a 5D with lens the price /performance ratio is definately in my favor. Oops. No. SNR vs. ISO stops don't work that way. An exposure at ISO 100 captures twice as many photons as ISO 200, so cutting the sensor area in half means your ISO 100 has the same SNR ratio as the larger pixel's ISO 200. (That is, a one stop higher ISO has 1.414 times the noise, not twice the noise.) (The price/performance ratio is still in your favor, thoughg.) So you've lost _more than three_ stops of SNR ratio. The 5D at ISO 800 looks better than the P&S at ISO 100. And the 5D user has f/1.4 and f/2.0 lenses if s/he wants, which are non-existent and rare in the P&S world nowadays. This is one of many reasons why small sensor point-and-shoots can't compete with DSLRs in terms of noise adn high ISO performance. Again... NOT an IS issue. The Imaging-resouce noise data for the S3IS does NOT follow the theory and physics of Momma Nature noise. The noise in the dark patches--the shadow areas in low light photography where S/N is most important-- is 4 X worse than it should be. I don't know if this is wrong (due to the above mistake) or not, but it might be. David J. Littleboy Tokyo, Japan |
#27
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Image Stabilization vs Noise
On Sat, 23 Dec 2006 01:46:34 -0800, "Mark²" mjmorgan(lowest even
number wrote: jpc wrote: Based on some published information from a review site, IS point and shoot camera seem to be more noisy than non IS camera. This I'm blaiming on electrical pickup from the piezo motors used to move either a lens element or the sensor. Anyone have any experience or comments on this topic Comments? Yes: Complete ********. See my reply above. I'm talking physics, data, and proceedures for evaluating the data if anyone wishes to confirm what I'm saying. I'm even willing to cheerfully admit I'm wrong if anyone can come up with an alternate and better explanation to the conclusions I've drawn from the data. What more can you ask. jpc |
#28
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Image Stabilization vs Noise
On Sat, 23 Dec 2006 23:44:29 +0900, "David J. Littleboy"
wrote: "jpc" wrote: As I stated in my follow-up post to David Taylor the 5D has a pixel size of ~70 sq microns and an active sensor size of ~45 sq microns. The Oly SP350--a much underrated camerra I ended up buying--has an active sensor size of ~5 sq microns. Photon shot noise, Poison noise, or the random way Momma Nature tosses light into your lens is "roughly" determined by pixel size. The real parameter is pixel well depth--something the camera manufactures have decided not to tell us about. Since Momma Nature noise is determined by the sq root of the number of photo electrons collected and the square root of 9 is 3, the SP350 has a S/N 3 time worse than the 5D in the regions where Momma Nature noise dominates. This is what theory predicts, this is what the data from Imaging- resourse shows and most important to me--this is how the SP350 I bought performed when I tested it. So far so good, but... So I've lost a stop and a half of signal to noise by buying a camera that some in this group automatically trash .But since I paid 20X less that a 5D with lens the price /performance ratio is definately in my favor. Oops. No. SNR vs. ISO stops don't work that way. An exposure at ISO 100 captures twice as many photons as ISO 200, so cutting the sensor area in half means your ISO 100 has the same SNR ratio as the larger pixel's ISO 200. (That is, a one stop higher ISO has 1.414 times the noise, not twice the noise.) Agreed. Half the photoelectrons in the pixel well, 1.4 times more noise (The price/performance ratio is still in your favor, thoughg.) So you've lost _more than three_ stops of SNR ratio. The 5D at ISO 800 looks better than the P&S at ISO 100. Right,again. My mental miscalculation ISO 400 (2 stops and 4X gain) gives 2X noise. ISO 800 (3 stops and 8X gain) give 3X noise. Which is what the imaging-resource data says--a 3X noise difference between the two camera. And the 5D user has f/1.4 and f/2.0 lenses if s/he wants, which are non-existent and rare in the P&S world nowadays. This is one of many reasons why small sensor point-and-shoots can't compete with DSLRs in terms of noise adn high ISO performance. Again... NOT an IS issue. Agreed-partially. If we're talking about photon noise--the noise source where sensor size is an issue--it doesn't matter is you fill the pixel well in a 1/1000 of a second or a 1/10 off a second. The S/N is still the same until you reach a shutter speed where thermal noise becomes a problem. A f1.4 lens obviously will fill the pixel well in a 1/4 the time as a f2.8 lens under identical conditions. So my buddy's $5000 colection of camera and lens will beat my $225 camera, it's heavy weigh vs light weigh, but I don't think lens speeds have much to do with my question. The Imaging-resouce noise data for the S3IS does NOT follow the theory and physics of Momma Nature noise. The noise in the dark patches--the shadow areas in low light photography where S/N is most important-- is 4 X worse than it should be. I don't know if this is wrong (due to the above mistake) or not, but it might be. Here's my question restated. The SP350 and S3IS have roughly similar size pixel and should have roughly 3-4X more photon noise than the 5D. The S3!S has 10-12X more noise. Where is the extra noise coming from? jpc |
#29
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Image Stabilization vs Noise
"DougL" wrote in message ps.com... Skip wrote: "J. Clarke" wrote in message ... On Thu, 21 Dec 2006 14:43:06 -0800, DougL wrote: Skip wrote: "jpc" wrote in message ... Based on some published information from a review site, IS point and shoot camera seem to be more noisy than non IS camera. This I'm blaiming on electrical pickup from the piezo motors used to move either a lens element or the sensor. Anyone have any experience or comments on this topic jpc I'm guessing it's because the p&s IS cameras have "digital" stabilization, which, in many cases, is merely a bump up for ISO and shutter speed, which, of course, results in more noise... -- Skip Middleton www.shadowcatcherimagery.com www.pbase.com/skipm Exactly right, as finally concluded in this long thread over the last two days. http://tinyurl.com/yj7mpq Turn it off, if you can, if you don't need it. Note too that digital image stabilization (DIS) has neither a stabilization sensor, nor does any image motion. Just ISO bump up, which amplifies system noise as well. We finally concluded that calling this IS was quite misrepresentative. Optical image stabilization (OIS) has a tilt sensor, and a moving mirror to shift the image. Charge motion image stabilization has a tilt sensor, and shifts the image digitally in the pixels electronically. Inexpensive consumer cameras just have DIS. No sensor, no piezo motors, no nothing. Oh, GAWD. First most point and shoot cameras with image stabilization have optical image stabilization just like Canon and Nikon DSLRs. It's only the Fuji and possibly some other other cheap POS cameras that pretend that they do by increasing the ISO. Second, optical image stabilization does not use a "moving mirror", one of the elements in the lens moves, those elements all being lenses unless its a catadioptric. -- --John to email, dial "usenet" and validate (was jclarke at eye bee em dot net) The Oly FE-170 I was flummoxed into buying for my daughter for Christmas has "digital image stabilization," not an expensive camera, at $150, but from a respected mfr. I won't argue your other points, (moving mirror?), but some of them move the sensor, don't they? -- Skip Middleton www.shadowcatcherimagery.com www.pbase.com/skipm As I said, these inexpensive cameras just have DIS, and there isn't anything moving in this "stabiliztion system". Not even electrons between pixels. Never heard of moving the sensor. As in moving the CCD? Engineering-wise, that would be pretty challenging. Several DSLRs have that feature, now, the Sony A100, for one. -- Skip Middleton www.shadowcatcherimagery.com www.pbase.com/skipm |
#30
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Image Stabilization vs Noise
jpc wrote in message ...
On 22 Dec 2006 12:53:21 -0800, "DougL" wrote: Never heard of moving the sensor. As in moving the CCD? Engineering-wise, that would be pretty challenging. Agree with that 100 %. Here's my version of camera shake correction---AKA IS Take a five foot length of light chain, attach it to a 1/4-20 bolt and screw into the tripod mounting hole of the camera. Wrap the camera strap around your neck and arm like it is a rifle sling. Frame your shot, step on the chain, and pull the camera taunt. Instant tripod. After some practice, I been able to take some reasonable hand held pictures with 1/4 to 1/2 exposure times. Don't know how this stacks up against the fancier version but I bet it's in the ball park. jpc I've carried around a length of light nylon twine with a bolt for 20 years, works well in a pinch, but not as well as IS or a tripod. -- Skip Middleton www.shadowcatcherimagery.com www.pbase.com/skipm |
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