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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 February 23rd, 2008, 06:46 PM   #1
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CMOS versus CCD

I'm a news photog, currently using the JVC GY-HD100. I'm planning to switch to the S270 because the JVC produces vertical smear on bright light sources, and going tapeless via Firestore HDD is not very relyable.

Now I've read that CMOS may exhibit skew, wobble and partial exposure because of "rolling shutter" technology. CMOS can use either “rolling” or “global” but as a practical matter all the camcorders on the market use the “rolling shutter” technology. See http://dvxuser.com/jason/CMOS-CCD/.

If the S270 demands controlled lighting avoiding any motion (always tripod mounted, never handheld) it's useless for news gathering.

Does anyone know, what kind of "shutter" the S270 uses? And if it uses a "rolling shutter" how noticeable those artifacts are?

Thanks in advance,
Andreas
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Old February 23rd, 2008, 07:50 PM   #2
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The 270 is CMOS so it theoretically should have the rolling shutter effect as well. In actual practice I have never had a problem but I have seen the effect on fast camera movement that I would have edited out anyway.

Both CCD and CMOS have their advantages and disadvantages: verticle smear for CCD vs. rolling shutter for CMOS. Nothing is perfect.
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Old February 23rd, 2008, 09:03 PM   #3
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High quality CCD's have very little vertical smear, but they are on higher priced cameras.

The EXMOR CMOS sensors that Sony is using show a lot less rolling shutter than you would think because of the way they read out the sensor.

Just remember, the RED camera also uses CMOS as a sensor and it's doing just fine in the image department.

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Old February 23rd, 2008, 10:31 PM   #4
 
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I've got a JVC HD110 and a Sony EX1. Most of the stuff I shoot is vast panoramas. Not a lot of motion in the images outside of the pans I induce. Still, I like the EX1 over the JVC hands down. The skew in motion on the EX1 is NOT noticeable.
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Old February 24th, 2008, 12:01 AM   #5
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The only big concern is if you plan to do a handheld matchmove. CCDs are best suited for that.
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I wait for the day cost-efficient global shutter 60fps capable CMOS sensors emerge for use on major manufacturers' cameras. (Sony, Canon, etc.) Rolling Shutters are a plague.
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Old February 24th, 2008, 06:22 AM   #6
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So I should not be worried too much about skew and wobble...

Last concern is "partial exposure": What about press conferences, where a lot of still photogs use their flashes?

If it looks like http://www.freshdv.com/mjeppsen/vide...r_artifact.mov I'll stay with CCD...
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Old February 29th, 2008, 10:54 PM   #7
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What about press conferences, where a lot of still photogs use their flashes?
I have used a V1U (CMOS) at dozens of media events for this year's presidential campaign in the U.S. And yes, the rolling shutter effect is real.

That said it is most obvious when stepping through frame by frame and a quarter to half of an image on a frame or adjoining frames is missing.

Mind you it is not a constant with the hundreds of flashes going off, but rather occasional and random, (several events have had 50 or more electronic crews and as many still photogs.)

The effect at speed, looks like a flash went off, and not unlike the flash frames seen when shooting 16mm film. It is not something that would automatically warrant plugging in a cuttaway.

Of course, there's a little voice that says, "what if the one frame where something extraordinary happens is the random frame and you know a still guy got the shot..."

I'd like shoot with the if the s270 in the field before deciding if it would be my primary camera. The next step is the XDCam for CCD 1/2 or 2/3 chips.
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Old March 7th, 2008, 01:17 PM   #8
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I just worked w/some red carpet footage shot w/a V1U and the partial exposure problem was pretty bad. One person who saw it said it looked like the camera was malfunctioning. Single, intermittent flashes going off might not look too bad, but on a red carpet w/flashes going off like crazy (and those "red eye reduction" pre-flashes) you start to get some insane looking banding as the different flashes catch the electronic shutter at different points in its "roll".

If you are doing a lot of events like these I'd stay away from CMOS cameras until they improve the tech (like implementing a global shutter).


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Old March 11th, 2008, 05:22 AM   #9
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HVR-S270 rolling shutter

Hi all,

I need to buy new camera. New Sony S270 spec looks good. One serious detail to think: CMOS "rolling shutter" issue. I do filming on receptions and on other events where photo flashes and fireworks are 100% part of event.
Have You sample footage from event ( like I described) or have You seen Sony's own sample footage. For example interesting object is waterfall under light.
Please feedback!

With
Best
Sulev
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