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Sony HVR-Z7 / HVR-S270
Handheld and shoulder mount versions of this Sony 3-CMOS HDV camcorder.


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Old March 24th, 2008, 05:16 PM   #1
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Truely 1920x1080?

I was trawling the Sony Pro site yesterday looking at the specs of these new cameras, they both seem like great pieces of technology and the ability to change lenses has almost sold me.

However reading the specification for these cameras I am led to believe that the CMOS sensor are only about half full HD resolution. From Sony's own brochure the stated number of pixel elements is 1,037,000 (x3). Now doing some simple maths 1920x1080 = 2,073,600. The Sony sensor elements are exactly half this! Nominally 1358x764.

I take it this has somthing to do with Sony's sensors being on a 45 deg. angle but in the end this says to me that they are interpolating the sensor data to get full HD.

Can someone confirm this is correct?

I reserve the right to be wrong.
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Old March 24th, 2008, 05:37 PM   #2
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Originally Posted by Dean Gough View Post
Now doing some simple maths 1920x1080 = 2,073,600. The Sony sensor elements are exactly half this! Nominally 1358x764.

I take it this has somthing to do with Sony's sensors being on a 45 deg. angle but in the end this says to me that they are interpolating the sensor data to get full HD.

Can someone confirm this is correct?
Firstly, I assume you're referring to the Z7? In which case, then each sensor has not 358x764 sensors, but 960x1080 - with the red and blue pixels offset from green, so horizontal pixel shift can be used. Pixel shift is reckoned to improve luminance resolution by a factor of about 1.2-1.3x, so (lens etc permitting) expect about 1200-1300 horizontally.

It's an HDV camera, with a recording raster of 1440x1080 for luminance, so you could argue the front end is quite well matched to the recorded raster.

Does the 1440 figure leave you feeling cheated? Well, it's the same as HDCAM downsamples to for recording, better than DVCProHD at 1280, and until recently few displays could manage any better. The move may well be towards a 1920x1080 world, but 1440x1080 is much better than SD and until recently has been at the technical limits.

It also enables the Z7 to have the same size pixels as the EX1, so should be comparable sensitivity. (The EX1 has twice as many pixels, but on a chip twice as big.)
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Old March 24th, 2008, 05:44 PM   #3
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Yes you are correct that the sensor data is interpolated but so is every other camera. They all do it slightly different but the sensor supplies data to a DSP that then uses this data to create whatever the design pixel output desired. This is then further processes for direct output from the analogue or digital outputs or for recording medium ( HDV is 1440x1080i or 1280x720 etc depending on flavor !!!) AVCHD has another set of options( 1920x1080, 1440x1080, SD etc) all created from the same sensor but created within the DSP/Bionz processor in the Sony. IF you look at the 45 deg layout of the Sony imager and imagine pixels at the centers of the imagers and the intersections you will end up with the 1920x1080. The DSp takes the data from all the sensors and creates a matrix that may coincide with some of the sensors.

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Old March 24th, 2008, 07:13 PM   #4
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Same as HDCAM (as David notes above). Therefore a complete non-issue.
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Old March 24th, 2008, 10:49 PM   #5
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Thanks for clearing that up.
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Old March 25th, 2008, 04:46 AM   #6
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Yes you are correct that the sensor data is interpolated but so is every other camera.
Most, maybe, but that statement is becoming less true. The EX1 has 3 1920x1080 chips (and makes a 1920x1080 recording) and chips such as that are increasingly becoming the norm on higher end cameras. Similarly, whilst HDCAM and DVCProHD are downsampled, HDCAM SR and 100Mbs AVC-Intra aren't. Hence my comment about the "move may well be towards a 1920x1080 world", and that's certainly true for screen resolutions as well.

I feel what the Z7 does is sensible for a camera in that price range, with those size chips.
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Old March 25th, 2008, 09:23 AM   #7
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The concern over sensor resolution is misplaced. Even the full 1920x1080 chips aren't receiving that much res from the glass. Remember there's an OLPF (optical low pass filter) on the face of the sensor, so even if the glass in the lens really does resolve that high, that's not what's reaching the chips -- and that's by design. What happens at the sensor does not ultimately define the image. Far too many other elements affect the process.

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I feel what the Z7 does is sensible for a camera in that price range, with those size chips.
And really that's what matters most. Thanks for pointing this out,
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Old March 25th, 2008, 04:02 PM   #8
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When viewed in a typical living room, 1440x1080 images essentially look no different than 1920x1080 images, even on a large screen television (assuming you are sitting at a reasonable distance from the screen). The human eye simply cannot really resolve more detail than that. Try shooting some stills with a good DSLR and then downsampling them to 1440x1080 and 1920x1080 and compare them on a good 1080p LCD (again, at a reasonable distance, like you would watch television comfortably at). If you can see the difference, you have exceptional eyesight.
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Old March 25th, 2008, 09:02 PM   #9
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Hi Dean,

You are correct, and it is confusing.

When I was trying to determine if the Z7 was going to have the same soft image as the Z1 did I was really asking if the chip was still a lower res chip or was the processing better to get the low res chip to look more detailed.

Well, my reference is the Canon A1, so I got the Z7 in, hooked it up a monitor and was very surprised to see a fairly soft image.

Don't get me wrong, it is clearly more detailed then a Z1, but the noise is also higher, and the detail is clearly less then a Canon A1. Compared to a Canon Hv-20 that has a true 1920x1080 cmos chip (and any other true full HD chip cam with no interpolating) the image was at least 25% less detailed and window-like.

It does many things well, so don't use this as the only factor. Sony has done a good job at getting the image to be better in low light, but at the expense of noise and detail from a chip that is interpolating.

My point is, the chip may be supplying the HDV codec with the proper amount of info to satisfy the HD requirement, but it is still visually softer and less detailed then a HDV cam that has true 1920x1080 chips. The Canon uses full HD chips, but only uses 1440 for the image. The smaller Sony consumer cams, as well as the Canon Hv-20 hits you with a full 1920x1080 and it shows more detail on screen in every part of the image that you eye looks to see detail.

My advice....get one in your hands and hook it up to a monitor. The bigger the better since the average size TV is now 40" being sold. And compare a few cameras. It will be worth your while.
My experience so far has proven that there is a very big difference between taking a well shot full HD image and showing it downscaled on broadcast TV, compared to a low res capture like we are getting from that new Sony chip and showing it on the same TV. Try it and you will see. Even though you are watching cable and it was streamed at 720, it still can look much more detailed since it's original image was shot with a $50,000 full HD hi grade cam. It was hard for me to understand until I now see it on a monitor.

Just my opinion, but hook that baby up. It may or may not be perfect for you. It has some very nice features to it.

Hope this helps,

Paul
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Old March 26th, 2008, 01:23 AM   #10
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Hi Paul, thanks for your input. Any new camera is meant as a replacement for my XL1H Canon. I am looking at the EX1 as it has full HD sensors and SDI, shame it does not have a removeable lens system like the Z7. I really like the idea of tapeless workflow and Canon does not seem likely to be upgrading the XL1H any time soon.

Guess I'll just have to get my hands on a variety of cameras and see for myself.
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Old March 26th, 2008, 07:38 AM   #11
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Hey Dean,

I almost bought the EX1, but then I was hearing about a few issues I was hoping they would/could work through before I order one. In the mean time, I was hoping Canon would come out and trump them all since they seem to be so talented at watching, learning and then launching a new product.

I love a lot of things about my Canon A1, they just need a tapeless pro solution with a little bit better low light ability and they will take over the segment again.

The Z7 is in many ways a great camera, some of it is pure genious, then other things like the manual audio behind a door flap that hangs down in front of other manual buttons, that also slams magnetically shut when you close it hearing it on the cam mic is just plain stupid beyond belief. And not making it so you can set the zoom rocker on the lens to a specific speed and when you do try and use it it is either way to fast or way to slow. Again, it's like the R&D just came to a halt and someone took it from the engineer before they could complete the design.

I don't remember Canon launching cameras with so many defects as we are seeing in these new Sony Cams. I got my A1 and never found any quality issue at all, or software/firmware issue that was considered just wrong or rendered the cam unusable. Yes, people had requests, but not requests like ones we are hearing to solve vignetting problems or focusing problems, or loose lens barrels etc.

So I am waiting to see what happens. I think we will see some amazing products coming out soon that will fit our needs better then either of these new solutions. At least I can only hope.

Paul
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