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Old Jan 15, 2008, 10:08 AM   #1
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Kodak Z812 IS, Z1275, V1253 three different cameras, surely one produces better video than the other; right?

Here are some general questions I have about digital image capture:

What does the camera's sensor do and why does one size at a certain MP perform better than another at the same MP? Could 10 MP look better than 12 MP on the same sensor?

Does the size of the sensor affect video quality? (Z812is, Z1275, and V1253 all take 720p @ 30fps, should one be better than the other?)

Regarding image quality, doesn't the size of the lens make a difference? (the Z812is lets in more light than the Z1275 which lets in more light than the V1253. Wouldn't this also affect video quality?)

I recently purchased the V1253 and have been happy with the videos it's produced, but I can't help but wonder if one of the other kodak cameras would produce something better. I've only shot using the 720p HQ setting which I believe records at a 13mbps bitrate, not really clear on what that means (less compression?), on a 2GB Extreme III that reads and writes upto 20MBps. The Z812is and Z1275 record at 10mbps at best, what difference should that make in the video produced?

I also have always disabled the digital image stabilization when ever I use the camera as I understand it reduces the quality of the image. Is that true?

I've owned several Kodak digital cameras and currently use a C875 as my main camera for everyday picture taking. I bought it when it was first introduced and have been very happy with the pictures it takes, so it'll continue to be my primary picture taking camera. The V1253 is not as ergonomically designed and doesn't feel as secure in hand, but I purchased it strictly for economical HD video capture. I initially tried the Aiptek A-HD, but the plastic lens produced a soft picture, the video recorded in hand was shakey, and it didn't do well with panning or action. In my opinion the V1253 performs much better.

I'm not looking for professional quality video, I can't afford it. I'm just looking for the best HD that records to SD cards in the price range I can afford, which right now happens to be under $300.

I'm considering the Z1085 IS as it looks as though it would be easier to grip, similar to my C875, and it has optical IS. I wonder if it's going to have the 720p HQ option like the V1253.
Thanks,
Gerry
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Old Jan 17, 2008, 7:07 AM   #2
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gerrydsjr wrote:
Quote:
What does the camera's sensor do and why does one size at a certain MP perform better than another at the same MP? Could 10 MP look better than 12 MP on the same sensor?
First, different companies make image sensors, and so there are variations between the products of different companies. Second, all companies make multiple sensors, some physically larger than others, so there will be variations from one model sensor to another. Third, when different companies put the same sensor in their cameras, the image processing they each do will create variations between cameras.

But, all other things being equal, a 12MP image sensor will always produce a better image than a 10MP image sensor.

gerrydsjr wrote:
Quote:
Regarding image quality, doesn't the size of the lens make a difference? (the Z812is lets in more light than the Z1275 which lets in more light than the V1253. Wouldn't this also affect video quality?)
A larger aperture lens will let in more light, and so will allow correct exposure in lower light. But a larger aperture lens is also tougher to make, so a bad onewould actually decrease image quality. Good large aperture lenses are expensive, and so usually don't show up in P&S digicams.

gerrydsjr wrote:
Quote:
I recently purchased the V1253 and have been happy with the videos it's produced, but I can't help but wonder if one of the other kodak cameras would produce something better. I've only shot using the 720p HQ setting which I believe records at a 13mbps bitrate, not really clear on what that means (less compression?), on a 2GB Extreme III that reads and writes upto 20MBps. The Z812is and Z1275 record at 10mbps at best, what difference should that make in the video produced?
Video really doesn't tax a camera verymuch.For instance, your V1253 is a 12MP digicam. It iscapable of taking still images at a resolution of 4000x3000. When you use it to shoot video, even at 720p HQ, that's a resolution of less than 1MP. over 90% of the data that the image sensor is capable of collecting is being ignored when you make a video. Granted, it must transfer that data to the flash memory card at 30 fps, but that doesn't tax the camera at all, only the flash memory card and interface. A larger buffer means that if your camera has a slower throughput and you're using a slow memory card, you can take longer continuous video clips, but it won't affect the quality.

gerrydsjr wrote:
Quote:
I also have always disabled the digital image stabilization when ever I use the camera as I understand it reduces the quality of the image. Is that true?
Because of the way that DIGITAL image stabilization works, ithas the potential of degrading the image. Butthat degradation isusually less noticeable in video thanthe camera shake it is designed to correct.
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Old Jan 17, 2008, 6:39 PM   #3
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For the record the 8MP Z812 has a 1/2.5 sensor. The Z1275 and the V1253 have a larger 1/1.72 sensor. The Z812 has optical image stabilization. The to be released V1273 and Z1085 are slated to have OIS as well.
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Old Jan 24, 2008, 2:41 PM   #4
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Thank you, TCav and ac.smith for taking the time to respond to my post.
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Old Mar 27, 2008, 2:47 PM   #5
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I had to post, because I think I disagree with each of these points.



gerrydsjr wrote:
Quote:
What does the camera's sensor do and why does one size at a certain MP perform better than another at the same MP? Could 10 MP look better than 12 MP on the same sensor?
Quote:
First, different companies make image sensors, and so there are variations between the products of different companies. Second, all companies make multiple sensors, some physically larger than others, so there will be variations from one model sensor to another. Third, when different companies put the same sensor in their cameras, the image processing they each do will create variations between cameras. But, all other things being equal, a 12MP image sensor will always produce a better image than a 10MP image sensor.
Depending on what you mean by "all other things being equal." If the sensor die is at a fixed size, it is often the case that lower megapixel counts are much better. To make high megapixel counts, the individual pixels are made very small. Since each pixel needs a certain amount of support circuitry, the light gathering area gets much smaller, and the overall performance of the pixels gets much worse. Further, many other optical and electronic effects get horrible as the pixel size gets too small. The megapixel race is hopefully ending. Given a fixed size of a sensor, using megapixels as a metric of image quality is like using slice-count as a metric of bread quality. We are already at the bag-of-crumbs stage for most sensors.

gerrydsjr wrote:
Quote:
Regarding image quality, doesn't the size of the lens make a difference? (the Z812is lets in more light than the Z1275 which lets in more light than the V1253. Wouldn't this also affect video quality?)
Quote:
A larger aperture lens will let in more light, and so will allow correct exposure in lower light. But a larger aperture lens is also tougher to make, so a bad one would actually decrease image quality. Good large aperture lenses are expensive, and so usually don't show up in P&S digicams.
A smaller F#. A larger aperture doesn't matter by itself.

gerrydsjr wrote:
Quote:
I recently purchased the V1253 and have been happy with the videos it's produced, but I can't help but wonder if one of the other kodak cameras would produce something better. I've only shot using the 720p HQ setting which I believe records at a 13mbps bitrate, not really clear on what that means (less compression?), on a 2GB Extreme III that reads and writes upto 20MBps. The Z812is and Z1275 record at 10mbps at best, what difference should that make in the video produced?
Quote:
Video really doesn't tax a camera very much. For instance, your V1253 is a 12MP digicam. It is capable of taking still images at a resolution of 4000x3000. When you use it to shoot video, even at 720p HQ, that's a resolution of less than 1MP. over 90% of the data that the image sensor is capable of collecting is being ignored when you make a video. Granted, it must transfer that data to the flash memory card at 30 fps, but that doesn't tax the camera at all, only the flash memory card and interface. A larger buffer means that if your camera has a slower throughput and you're using a slow memory card, you can take longer continuous video clips, but it won't affect the quality.
Video is very taxing. The data rates, processing requirements, storage bandwidth, storage size all go way up. The sensor gets hot and it is hard to get good quality out of a hot sensor. It uses more battery power.

gerrydsjr wrote:
Quote:
I also have always disabled the digital image stabilization when ever I use the camera as I understand it reduces the quality of the image. Is that true?
Quote:
Because of the way that DIGITAL image stabilization works, it has the potential of degrading the image. But that degradation is usually less noticeable in video than the camera shake it is designed to correct.
Digital image stabilization, depending on how it is done, can improve image quality. Some cameras even use it on still images. You can combine information from multiple frames to get better image quality. Badly done digital stabilization, of course, can hurt image quality.
If you are trying to fix hand shake, a tripod and more light will always be great if you can have that stuff. As digital gets better, it could potentially do as well or better than optical.


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Old Mar 27, 2008, 4:06 PM   #6
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Nice first post Amnon...

Let the flood gates open...

the Hun

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Old Mar 27, 2008, 8:12 PM   #7
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I agree - nice going Amnon.

I would suggest that however well the digital stabiliztion works, a tripod (or at least a monopod) is a really good idea for video. No image stabilization will get rid of the kind of motion that can lead to sea sickness when watching home video.
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Old Mar 27, 2008, 10:17 PM   #8
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Amnon wrote:
Quote:
I had to post, because I think I disagree with each of these points.



gerrydsjr wrote:
Quote:
What does the camera's sensor do and why does one size at a certain MP perform better than another at the same MP? Could 10 MP look better than 12 MP on the same sensor?
Quote:
First, different companies make image sensors, and so there are variations between the products of different companies. Second, all companies make multiple sensors, some physically larger than others, so there will be variations from one model sensor to another. Third, when different companies put the same sensor in their cameras, the image processing they each do will create variations between cameras. But, all other things being equal, a 12MP image sensor will always produce a better image than a 10MP image sensor.
1) Depending on what you mean by "all other things being equal." If the sensor die is at a fixed size, it is often the case that lower megapixel counts are much better. To make high megapixel counts, the individual pixels are made very small. Since each pixel needs a certain amount of support circuitry, the light gathering area gets much smaller, and the overall performance of the pixels gets much worse. Further, many other optical and electronic effects get horrible as the pixel size gets too small. The megapixel race is hopefully ending. Given a fixed size of a sensor, using megapixels as a metric of image quality is like using slice-count as a metric of bread quality. We are already at the bag-of-crumbs stage for most sensors.

gerrydsjr wrote:
Quote:
Regarding image quality, doesn't the size of the lens make a difference? (the Z812is lets in more light than the Z1275 which lets in more light than the V1253. Wouldn't this also affect video quality?)
Quote:
A larger aperture lens will let in more light, and so will allow correct exposure in lower light. But a larger aperture lens is also tougher to make, so a bad one would actually decrease image quality. Good large aperture lenses are expensive, and so usually don't show up in P&S digicams.
2) A smaller F#. A larger aperture doesn't matter by itself.

gerrydsjr wrote:
Quote:
I recently purchased the V1253 and have been happy with the videos it's produced, but I can't help but wonder if one of the other kodak cameras would produce something better. I've only shot using the 720p HQ setting which I believe records at a 13mbps bitrate, not really clear on what that means (less compression?), on a 2GB Extreme III that reads and writes upto 20MBps. The Z812is and Z1275 record at 10mbps at best, what difference should that make in the video produced?
Quote:
Video really doesn't tax a camera very much. For instance, your V1253 is a 12MP digicam. It is capable of taking still images at a resolution of 4000x3000. When you use it to shoot video, even at 720p HQ, that's a resolution of less than 1MP. over 90% of the data that the image sensor is capable of collecting is being ignored when you make a video. Granted, it must transfer that data to the flash memory card at 30 fps, but that doesn't tax the camera at all, only the flash memory card and interface. A larger buffer means that if your camera has a slower throughput and you're using a slow memory card, you can take longer continuous video clips, but it won't affect the quality.
3) Video is very taxing. The data rates, processing requirements, storage bandwidth, storage size all go way up. The sensor gets hot and it is hard to get good quality out of a hot sensor. It uses more battery power.

gerrydsjr wrote:
Quote:
I also have always disabled the digital image stabilization when ever I use the camera as I understand it reduces the quality of the image. Is that true?
Quote:
Because of the way that DIGITAL image stabilization works, it has the potential of degrading the image. But that degradation is usually less noticeable in video than the camera shake it is designed to correct.
4) Digital image stabilization, depending on how it is done, can improve image quality. Some cameras even use it on still images. You can combine information from multiple frames to get better image quality. Badly done digital stabilization, of course, can hurt image quality.
If you are trying to fix hand shake, a tripod and more light will always be great if you can have that stuff. As digital gets better, it could potentially do as well or better than optical.


Now it's my turn to disagree. I've numbered Amnon's comments for reference.

Comment 1) I think we can agree that with the same sensor technology smaller pixels degrade S/N ratio. We also should be able to agree that the more pixels the greater the enlargement that can be done before pixelization becomes apparent. Obviously two conflicting factors to IQ. Inresolution comparisons I'veseen at DPReview where the same camera is "upgraded" to a new model by replacing the sensor with a same sized higher MP sensor the tested resolution has increased in spite of DPReview's railings about noise and/or detail lost to noise reduction. An example case illustrating this is the Canon S3 (6 MP) vs. S5 (8 MP). The S5 lens (sames as S3) demonstrates higher resolution. Another point, the optimal aperture of the S5 was found to be f/4, the theoretical diffraction limit for a 1/2.5 sensor vs. an optimal aperture of f/4.5 for the S3.

Related point - the pixel size on an 8 MP 1/2.5 sensor is about the same as 12 MP with a 1/1.72 sensor.

Comment 2) I'm not reallythe point to be madehere. TCav's point was that you won't find an F/2 12x (or 3x for that matter) lens on a P&S. I also believe TCav's use of the term aperture isentirely correct.

Comment 3) Video is not taxingthe sensor on a Z812 orZ1275/1285. It is already producing a higher resolution video stream continuously to run the LCD/EVF viewing systems. Producingan actual video may increase the load on the CPU to run the compression and the data writing subsystem, but not the sensor which was TCav's point.

Comment 4) Wikipedia does have a short explanation on at least a couple of methods of digital image stabilization. Its purpose in video is not to enhance detail but rather to keep constant framing (avoid viewer fatigue and motion sickness). Well implemented it does seem to work. Applying this same general technology to still images has generally been criticized by trusted reviewers as causing excessive loss of detail. That some manufacturers apply both optical and digital stabilization to still images should not be taken as a sign that digital stabilization is a good technology for still images, just a marketable one.

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Old Mar 28, 2008, 10:31 AM   #9
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At least in my palmcorder (Canon DC210) digital image stabilization (DIS) does little or nothing for the slow motion sickness kind of wobble/tilt. It does do a good job on high frequency jitter of the kind shooting from a moving car produces.

DIS does reduce resolution since it must reserve some of the pixels along the edges to work. By 20% in my case (from 0.45 to 0.34Mpixels).
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Old Mar 28, 2008, 11:06 AM   #10
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Bill:

Hey, thanks for some real evaluation of dis in camcorders. I appreciate the feedback.

A. C.


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