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Sony HVR-V1 / HDR-FX7
Pro and consumer versions of this Sony 3-CMOS HDV camcorder.


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Old December 15th, 2008, 12:02 PM   #1
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Strange Results

I recently tried to shoot some footage of clouds moving in front of a full moon at night with my V1U, and got some strange results that I cannot explain. I'm hoping that someone here might have some idea as to why they occurred and how I might avoid it from happening again.

I was shooting to tape at 24pA, I had the iris manually set to f.4, the gain at 0db, the shutter speed at 40. All settings were in manual mode and not allowed to vary automatically. On my cameras LCD screen the image of the moon appearing and disappearing behind the clouds looked terrific. I couldn't wait to get home to view the results on my full size LCD screen. When I did though, what I saw was footage that "looked like" it was shot in all auto mode, with the iris opening and closing as the scene got lighter and darker. And not opening and closing smoothly, but in obvious "steps" up and down. I couldn't believe it. I always keep all the settings visible on my screen when I shoot so I know exactly what the camera is doing at all times. After seeing the footage I even switched back to camera mode to check the settings and they were still set exactly as I had left them.

Could the cold temperature have had something to do with it? Did the fact that the zoom was fully extended play a role? I've shot in cold temperatures before though during the daytime and never saw anything like this.

Another strange thing was the way the bright edge of the moon occasionally rippled slightly. This was another aberration that made the footage look unusable.

Unfortunately I am not currently in a position to be able to upload any footage. And due to the fickle nature of the weather, not able to recreate the scene/conditions that I shot.

Has anyone experienced anything similar, or know why that might have occurred?
James McCrory is offline   Reply With Quote
Old December 15th, 2008, 03:38 PM   #2
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I have shot the moon many times with my V1, I use manual settings and play with the iris, and the shutter speed, shutter speed might fairly high depending on your zoom and the moons brightness that night. when focusing and when you can make out all the moons features, and its not just a round ball, you could lock your settings. I usually start with moon in one corner of viewfinder because its moving, 10 minutes and it will be out of range and cam has to be adjusted. This has worked for me
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Old December 16th, 2008, 03:42 AM   #3
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I also have shot the Moon many times with the FX7E in completely manual mode with excellent results (frankly, it is my favorite object for filming).

It’s not enough to manually control your camera’s shutter speed, iris and gain to be fully in charge of your frame. In fact, the V1 has a lot of automatic functions, which run the image acquiring even when the cam’s main parameters are locked by an operator.

In the case of the moon and night sky shooting, the most important ones (actually, those you can manage) are CNTRST ENHCR (contrast enhancer), KNEE POINT and BLK COMPNSTN (black compensation).

The contrast enhancer function (enabled by default) is constantly trying to detect high contrast parts of the image and reducing unexposed shadows there. Analogously, the knee point function (which is in auto mode by default) is trying to prevent overexposure of the picture’s highlights by moving the starting point of the video gamma-curve. In its turn, the black compensation (if it is activated) is stretching or compressing the gamma-curve in the picture’s dark areas.

All these functions can affect your picture effectively changing the overall brightness of the scene, for example.

So, my advice: next time deactivate these functions before shooting. And good luck to you: this Friday the Moon is going to be 15 percent larger and 20 percent brighter than usual.
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Old December 16th, 2008, 09:22 AM   #4
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Hmm... perhaps the contrast enhancer

I always keep the knee set to 'low', the black compensation to 'stretch', and the contrast enhancer 'on' in order to get the most latitude. I also keep the sharpness at '3' in order to avoid that harsh look that too much sharpness can give an image.

Perhaps the 'contrast enhancer' is the culprit. Maybe it is unable to deal with such wide and constant swings between light and dark gracefully. Although I don't know why that should be so. It would make the contrast enhancer more of a flaw than a real viable shooting option.

I'm beginning to wonder if it is also responsible for some of the flickering I sometimes see when I do slow zoom outs on a scene in which the dynamic range changes dramatically.

Has anyone else experienced anything similar?
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Old December 16th, 2008, 07:15 PM   #5
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Quote:
Originally Posted by Arkady Bolotin View Post
In the case of the moon and night sky shooting, the most important ones (actually, those you can manage) are CNTRST ENHCR (contrast enhancer), KNEE POINT and BLK COMPNSTN (black compensation).
Note that the latter two are exclusive to the V1 and are not available on the FX7.
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Old December 16th, 2008, 09:14 PM   #6
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I had this happen once! I thought I forgot to put everything on manual. It was only the bright part of the sky so I bet the Knee was set to auto.
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Old December 17th, 2008, 08:09 AM   #7
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No the Knee point was definitely set to 'Low'. I never change that.
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