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04-30-2009, 03:20 PM   #31
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QuoteOriginally posted by mutedphotos Quote
I'm not an expert on sensors so I may be completely wrong here, but my understanding is that the S/N ratio has nothing to do with the size of the sensor itself, only how big the pixels on that sensor are. A 6mp sensor of any size will have a better S/N ratio than a 12mp sensor of the same size, because the 12mp sensor has to use smaller pixels to fit them all in.
Read this:
http://www.dxomark.com/index.php/eng/Insights/More-pixels-offsets-noise!

04-30-2009, 03:47 PM   #32
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QuoteOriginally posted by mutedphotos Quote
I'm not an expert on sensors so I may be completely wrong here, but my understanding is that the S/N ratio has nothing to do with the size of the sensor itself, only how big the pixels on that sensor are.
No not correct but for fun read this:
Depends on what you are trying to optimize: Open Talk Forum: Digital Photography Review
one finds that image S/N is only very weakly dependent on pixel size -- not nearly as much as one might conclude on the basis of viewing 100% crops, which display a smaller portion of the image for smaller pixels (and smaller image scales are invariably noisier), thereby skewing the comparison.
But read more, it gets quite interesting...
04-30-2009, 03:51 PM   #33
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QuoteOriginally posted by Philippos Quote
We don't know what the future holds for us. Maybe someone will make a new type of sensor that can produce ten times more pixels with ten times less noise in an even smaller area(something like the single-pixel sensor).
BBC NEWS | Science & Environment | Debut for world's fastest camera
Single pixel sensor...............
What is more, the camera works with just one detector, rather than the millions in a typical digital camera.

Dubbed Serial Time-Encoded Amplified imaging, or Steam, the technique depends on carefully manipulating so-called "supercontinuum" laser pulses.

These pulses, less than a millionth of a millionth of a second long, contain an enormously broad range of colours.

Two optical elements spread the pinprick laser pulses into an ordered two-dimensional array of colours.

It is this "2-D rainbow" that illuminates a sample. Part of the rainbow is reflected by the sample - depending on light and dark areas of the illuminated spot - and the reflections travel back along their initial path.
04-30-2009, 03:52 PM   #34
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Wow!

As for the question whether sensor size or pixel size matters ... Gimbal said it all.

I may even simplify the answer even more:

First, let me make sure that we all understand that the video output will be produced via downsampling. There is no center area cropped.

My question only was if the downsampling is via sub- or supersampling. Where I explained the terms in the second post.

Now, here we go (video = 1080p fixed size video):
  • for Supersampling, the sensor size will determine noise in video.
  • for Subsampling, the pixel size will determine noise in video!
Point is, while the dSLR sensor is much bigger, its pixels aren't, compared to a HD camcorder.

QuoteOriginally posted by Philippos Quote
I agree that the entire surface of the sensor should (and I'm sure it will) be used - otherwise it's meaningless.
If someone knows how the burst mode in K20d works, I believe we will have our answer.
Well, just accidentily, I once posted the most detailed analysis of the K20D burst mode in this forum.

It is here:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/21941-k20d-burst-m...esolution.html

The result is rather shocking: The K20D subsamples 768x1024 from the full sensor, i.e., it picks 3 colors from an array of 6x3 pixels. And it does it badly, producing unnecessary chromatic aberration artifacts.

So, in short: K20D uses subsampling

My earlier analysis is one reason why I am now critically questioning the quality of video to be expected from a dSLR...

Of course, subsampling is allright for LV.

QuoteOriginally posted by nixcamic Quote
Even sub-sampling will still give better noise than your average camcorder
I computed it above: Only if camcorder uses a sensor SMALLER than 1/2.3" ...

QuoteOriginally posted by Philippos Quote
Unfortunately, it is not only a matter of size, it is also a matter of good electronics.
Don't expect wonders.
Noise (at the pixel level) is the sum of read-out noise (the electronics) and Shot noise (from counting a discrete number of photons). The former is already rather low in modern cameras. The latter is only determined by two factors: pixel surface and quantum efficiency. The latter is already rather good as well (>50% in scientific devices). So, there is no other way than larger pixels. Sorry that physics is so unforgiving (and forget the black silicon exaggerations).


Last edited by falconeye; 04-30-2009 at 03:57 PM.
04-30-2009, 07:36 PM   #35
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Thanks for all the links guys, maybe I'm in a bit over my head here
04-30-2009, 10:57 PM   #36
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Falconeye, you think very conservatively. I'm taking about a major paradigm shift - that's why I mentioned the single-pixel sensor. Kind of what happened when we replaced our vidicon / saticon cameras to CCD ones.

Even when compared to film, modern sensors deal with noise / grain very well. The fastest film I have used is the TMY3200 which of course is BW and creates thick "artistic" grain - the same thing we would perceive as sensor noise on a DSLR. I have never even seen a color film available at these speeds. This however should not disencourage us from wanting more (you know, like the Sisters Of Mercy song...).


To return to our subject, K-7 & video that is, I have to say that I'm pretty sure it will be of superior quality to most (if not all) commercial camcorders, plus the real bonus for me is that I get to use my lenses for videography, something only Canon shooters could do (with the XL-1) until DSLRs got video recording capabilities.
04-30-2009, 11:46 PM   #37
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What concerns me most is the memory used. If indeed the sensor is capable of full HD. Will it be normal SDHC. ????? there are camcorders on the market that support full HD on SDHC. but how does that work?, will the image be so compressed that that is the only way it will work? Will there be a recoding cap when the buffer runs out.
You know that DDR800 is very cheap now. Very very cheap. I suppose the whole thing can be stored in buffer at a higher bitrate. 4GB buffer could be used. or at least 1gb. I would be very happy with an uncompressed format. One that would obviously require lots of SDHC 32GB cards.
Compact flash...... not likley as that is not the way Pentax have gone.
How about the first device to market with support for SDXC???? Also not likley but possible.
Then again we may be looking at this the wrong way.
The latest Canon has 1080p support at 20FPS. I would not imagine that it would be too difficult to make it 24FPS. ????? surely Pentax can support it in a product that will cost at least twice that.
Anyway, Anyone else concerned by SDHC,
compression on 1080p?
Codec used?
Anything I'm missing

04-30-2009, 11:59 PM   #38
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Steelski, a decent Class 6 SD is good enough for full HD video.
05-01-2009, 01:30 AM   #39
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Let’s say we will have subsampled video, then at least we could get a 2x digital zoom that actually works without compromising picture quality. Merely subsample a smaller area of the sensor.
05-01-2009, 02:21 AM   #40
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QuoteOriginally posted by Philippos Quote
Falconeye, you think very conservatively. I'm taking about a major paradigm shift
I am not conservative. To the contrary, actually. But I was taught to respect the laws of nature
(Which makes the one pixel sensor a silly device, btw -- except if you pump a lot of energy into the light source)
QuoteOriginally posted by Gimbal Quote
Let’s say we will have subsampled video, then at least we could get a 2x digital zoom that actually works without compromising picture quality. Merely subsample a smaller area of the sensor.
Good idea. Nonetheless, I fear that the subsampling would probably be rather hardwired.
05-01-2009, 02:37 AM   #41
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Video should be same as Pentax X70:

Movie capture in high-definition TV image quality with anti-shake protection
The X70 captures high quality movie clips, equivalent in image quality to that of high-definition TV (1280 x 720 pixels) at 15 frames per second. The X70 also features Movie SR mode,** which effectively minimizes annoying camera shake during movie capture. The X70 can also record video at 848x480, VGA and QVGA resolutions at 30 frames per second, for full video capture flexibility. As a result, the photographer enjoys high-quality, blur-free movie shooting with minimal effort.

spec can be improved, but not a lot.
05-01-2009, 03:37 AM   #42
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15 fps would be a real let down. (personally I think even 24/25fps is to little.)
05-01-2009, 03:39 AM   #43
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QuoteOriginally posted by Vaikis_ Quote
Video should be same as Pentax X70, equivalent in image quality to that of high-definition TV (1280 x 720 pixels) at 15 frames per second.
I certainly hope it isn't so.
I hope it's 1080p, I don't mind if it's 720p at all. But I want it to be REAL video stream and not the 15fps. It's completely useless. Even cell animation is 25 fps today.
I hope for 25 fps and possibly a 24 "cinema" mode.
Besides, the X70 is far from being the K-7.


QuoteOriginally posted by falconeye Quote
I am not conservative. To the contrary, actually. But I was taught to respect the laws of nature
(Which makes the one pixel sensor a silly device, btw -- except if you pump a lot of energy into the light source)
That's what I thought when I first read the white paper on TIs DMD: "interesting idea, but it's too exotic to become commercial". A few years later, the world is full of DLP projectors.

"Laws of nature". This is very vague. We don't even know what a photon is. We only know it's behaviour, after observation (and all it's measurable properties). We have been creating images by shooting electrons on phorsphor for decades, and we still don't know exactly what an electron is.

I am much more open minded in this. Black Silicon, Single-Pixel Sensor, Variable Sized Diode sensors, DIL, Quad sensor arrays and God knows how many other techniques and technologies are we about to see within our lifetime (BTW, the ones I mention are about two yars lod). If a 10% is succesfull, it means that within the next decade, resolution wil have quadrupled and we'll probably be talking about "kiloISOs", the same way we talk about ISO speed right now.
05-01-2009, 04:05 AM   #44
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I'm not willing to speculate on the K7 video capabilities but...

There is a VERY interesting review on the Canon 5d mkII at Toms Hardware.com.
Basically they say that the camera is very good except for the video, which they say is very difficult to use because of the way the AF on it has been implemented.
review here:
Canon EOS 5D Mark II: Amateurs Need Not Apply : A Serious Camera for a Serious Photographer

edit: yes this is primarily a computer hardware site, but I've found their camera reviews to be sufficiently professional (unlike Consumer Reports or CNET for instance)

NaCl(if I were a Canon system owner this review wouldn't make me want this camera)H2O
05-01-2009, 04:24 AM   #45
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QuoteOriginally posted by Gimbal Quote
15 fps would be a real let down. (personally I think even 24/25fps is to little.)
I personally hope that it is no more than 24 FPS.
the reason being that to me the 30fps looks hyper real. 24 FPS has the right amount of blur per frame to make it look as if an eye sees it. 30FPs looks strange to me. 60fps maybe, because the eye sees more than a couple of images per second and combines them into one. Besides. almost all motion pictures are 24fps.
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