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Old Oct 2, 2006, 2:46 AM   #1
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I have been comparing the low-light performance of a C6 with my "gold-standard" Optura 300 and Sony TRV900.

First, turn off the sharpening by switching video mode to "Soft" as this considerably reduces noise and MPEG4 blockyness. Use manual focus, as auto-focus gets pretty patchy at low light levels. 400 ASA is not too noisy, and is the best choice, even if you are going to post-process with an NLE.

The TRV900 is second only to the VX2000/VX2100 for low light performance (don't flame me, this is a subjective opinion) and the Optura 300 comes in close behind. I have two Optura 300s, and I typically use them at 1/60 sec frame speed. If I remember, they have about the same size CCD as the C6, a relatively big one.

At low light the TRV900 outpaces the C6 (and the Opturas) in every way. No surprises there.

When compared to the Optura 300s, the C6 has less noise than the Optura set to 1/60sec, and about the same as when the Optura is set at 1/30sec (low light setting on Optura).

With stabiliser off, the C6 resolves about 600 x 400 video lines, while the low light mode of the Optura limits it to about 500 x 250. No comparison there.

The chunkiness of the MPEG4 conversion (I only used SHQ) is easily annulled by using Mike Crash's Sony Vegas 'Dynamic noise reduction' filter
http://www.mikecrash.com/modules.php...page&pid=6
which gets rid of any annoying chunkyness, even at a low smoothness setting (I use 4 or 6).


Things I hate about the C6:
1. There is no way to change the Focus mode or the Backlight setting once you start video recording, holding the menu down for two seconds, and clicking the 'mouse' towards the bottom, only work when you are not filming. This is a major software defect IMO.
2. The battery only lasts for about 60 minutes of continuous SHQ recording, or 70 minutes if you turn the screen backlight totally off. This is not enough. Another 10 minutes would make all the difference.
3. It is very hard to mount the C6 on a tripod and feed power to it, for continuous shooting. I have tried to use the 1 inch square power/usb block, but it gets in the way of the tripod mount.
4. The lack of ability to handle 4 Gig SD cards would become a bigger problem if there was a solution for point (3) above.
5. When I record something important with a Mini-DV machine I use firewire and 'Scenalyzer' to stream the DV to my laptops' hard disks, just in case of tape dropouts. There is no way to stream video to disk with the C6 as its USB output only seems to handle 320x240 resolution.
6. No way to turn off the "Tally Lamp"
7. Stuck pixels and noisy pixels are both too numerous.

Good things:
1. Images taken in 7 lux are usable, once Sony Vegas /DNR is used to reduce the noise, and Sony Color Curves plug-in is used to compensate the black non-linearity (common in camcorders at low light levels).
2. Iimages at 15 lux are starting to get reasonable color saturation.

Can anybody suggest any solutions for the 'hates'?

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Old Oct 2, 2006, 12:01 PM   #2
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Hi Trev,

Thanks for the comprehensive and technicalcomparison (ie. going beyond just "the feel" and "the look")!

I totally wholeheartedly absolutely agree with all the disadvantage you pointed out - and I don't have any solution. I do, however,think this product was designed as a very portable P&S camera with a good video mode. It is really notin the league of a video camcorder in terms of functionality and flexibility.
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Old Oct 2, 2006, 12:16 PM   #3
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Ah, but wouldn't it be so nice if it was more easily usable in a tripod mode, as well as handheld:-)

Compact low-light camcorders are far and few between these days, and the 9-pixel mix does such a good job of controlling CCD sensor noise in low light.
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Old Oct 2, 2006, 4:27 PM   #4
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Yeah,your hatesseem to indicatethat you wantto shoot for hours straight while afixed to a tripod.Then anultra-compact portable like the C6 isn't required for this job?... or... what are you filming? I just bought a couple of extra cheap spare batteries and 2GB SD cardsand replace them when needed while travelling, works well and takes up little extra room, they all fit in a pouch in mypocket and can generally be recharged/backed up at night. Like Steve pointed out previously, it may be best to have four 1GB SD cards thenone 4GB since you don't have all your eggs in one basket in case of a failure and they take up so little room.
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Old Oct 2, 2006, 7:17 PM   #5
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RE: tripod mount blocking USB adaptor

What about finding an extra long screw that fits the tripod mount, so that it raises the body of the camera off the platform of the tripod? The camera will be then secured by the screw reaching the end of the thread, instead of the usual way being held tight against the tripod platform. It may not be as secure but it may work. This way you have more space to fit the black USB adaptor piece.

Did you find any external battery packs that provide the required wattage (volt amp) suitable for the C6, and a suitable power cable that has a small USB plug at the end (I don't know the polarity of the connection though)?

I agree, even though the C6 takes 2 GB cards, it is rather useless when you want to shoot continuously, because now the shooting time is limited by the battery. Of course there are no battery packs with a higher rating than the OEM 720 mAh in the market.
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Old Oct 2, 2006, 8:33 PM   #6
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Blindsight, I am going to try to locate a cupscrew that can be used as an extension for a tripod. I also am looking at threading a piece of cyclindrical plastic about 1 inch diameter, with a portion removed to clear the power block.

I have been doing darkframe measurements. Interesting that at ISO 400 the peak level of noise is about 10 units (on a scale of 1-255) in the still-picture mode. All of that disappears (except for a single, 28-unit high, hot pixel) when movie mode is enabled. I will be intrigued to see how they have pushed the gain another two f-stops (to ISO 800, 1600) in the new VPC-CG6 model. At least, I assume that is what they have done:roll: I doubt it is a totally new sensor, while they are still struggling to deal with quality control (hot pixels) in the current C6 sensor technology.


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Old Oct 2, 2006, 11:51 PM   #7
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Curio:

Highest ISO for still pictures quoted in the manual = 400

Highest ISO for video quoted in the manual = 3600

3600 / 400 = 9

Does this incidentally have anything to do with the 3 X 3 pixel mix technology that is supposed to improve low light performance? (Does it even work arithmetically this way?)

I worry that the new CG6's ISO 800/ 1600 will be disappointing, because Sanyo may be chasing trend like all other camera manufacturers in offering high ISO, without the benefits of a truly capable high-ISO CCD (like Fuji).

I guess the principle of "pixel mix" is the same as the "high ISO" mode of many digital still cameras, which makes (relatively) noise-free pictures at low resolution (eg. 0.3 MP). Instead of using only 0.3 MP of the sensor at high ISO, the camera uses all available pixels of the sensor, then combine neighboring pixels to shrink the picture, at the same time averaging out the noise. The difference with the Sanyo is that, it can do it continuously during video filming.

You got any thoughts about the external power source? (Did you miss my question?) Thanks.
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Old Oct 3, 2006, 12:30 AM   #8
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I am sure that the 9x factor comes from the 3x3 averaging technology. I also note that the hot pixel in my C6 is stuck at 100% in still photography, but at 1/9 (28/255) in movie mode. Which is what one would expect, I guess.

The USB power block has a tiny USB socket, and a power socket for the adaptor. The C6 cannot draw power over USB (and, one might ask, why wasn't it designed to do so??)

I have flirted with the idea of taking apart a battery (don't do this at home, folks, it is dangerous) and attaching two wires to run out the back of the C6 to an external battery pack. The standard cells for my Opturas are 2500maH at 3.7V instead of the 720maH of the internal unit, which would be an excellent boost.

I don't think I am going to be using my C6 much for tripod shoots, but I do record quite a few conferences, and I am always struggling with low light. The C6 performs well under these lighting conditions...



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Old Oct 4, 2006, 10:50 AM   #9
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I was just looking over Sanyo's site describing their new VPC-CG6 at URL
http://www.sanyo-dsc.com/english/pro...cg6/index.html

and I noticed some of my 'hates' seem to have been addressed by the CG6.
1. " Can also be charged from PC via USB cable"

2. "4 GB SDHC memory card compatible" (giving 2hrs 40minutes record time)

No mention of whether the USB "Video Class" can be activated to 640x480 Resolution, but one has to ask why there is a "PC Camera" class for webcam, and also a "Video Class," if there is no way to effectively use that Video Class? On the other hand, I have not tried to use one of the new video capture programs written for the HD video cameras. maybe they will sense the Video class. Hmm. I will try that later today...

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Old Oct 4, 2006, 11:36 AM   #10
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I drew a blank on that one - I could only find generic video MPEG capture software which used the PC's Firewire port for input.

Anyway, when I connected the C6 and selected "PC Camera" mode from its menu, I realized that there was no "Video Mode" option on that C6 selection screen:sad:

VirtualDub's Capture mode detected the camera properly, and was happy to record the MJPEG stream at 320x240 resolution. Not much use, but at least everything functioned correctly in Windows XP's "PC Camera" mode.

If only Sanyo had bothered to also correctly implement the "Video Class" for USB, as they imply in their specifications. I am seeing timing troubles, at the protocol level, which I assume are in the camera... They seem related to the MJPEG compression mode..:sad:


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