HDV and Lightning Problems?

[Mike Hollingshead]

I'm wondering if anyone has noticed any problems with their HDV camera around lightning. I watched footage on mine for the first time the other day and noticed there seemed to be some problem when taping around any lightning. Every flash would end up with an odd flicker like appearance. It looks alot like what vid cams do when a bolt hits very close to the shooter(like the cameras get some electrical interference). It did this on every single flash as I punched north and then east on the Coldwater KS supercell Saturday. So, the lighting at the time was around sunset. I thought the camera was bad when I first saw it. I let it play and noticed it wasn't the camera being bad but just what it wanted to do every single flash.

Later after sunset I had it on slow shutter and it was not a problem at all. I believe I even had one bolt after dark that was in the shot and it did not do it for that(not on slow shutter). So I'm wondering if anyone has noticed this. It isn't natural looking at all.

Also one other thing worth mentioning about HDV and lightning. MPEG(or much of any compression I imagine) can't handle very fast changes in the image(especially when it supposed to do it in real time). In lower light with some bright flashes, often more of the strobing kind, you will see the MPEG compression artifacts as it tries to quickly change from dark to bright. The only thing that seems to do somewhat well at this is encoding on a computer with a real encoder that takes time to analyze everything. This was the only time I could see enoding artifacts with this camera...well other than very low light when I'd try and make it brighter than it appeared(then it was just a big mess of noise).

Maybe these are only problems with the HC1 and lightning, but I doubt it. I imagine the FX1 uses the same encoding. Maybe it is fixable with various shutter speeds as it wasn't a problem with slow shutter on(1/8). So perhaps with 1/30 it will not happen and will manage to still look somewhat normal without the slow mo appearance of very slow shutters.

 

[cedwards]

I shot a little with my FX1 the other night. I set everything manually. o gain: 1/30 shutter speed. I didn't notice any artifacts like you mentioned. What is sounds like it could be if the image stabilization. You might try turning it off.

Other than that, how has the HC1 been for you? I was thinking of getting one for a backup.

 

[cedwards]

I havn't noticed the FX1 getting hot at all. It is a rather large camera so, it has plenty of room to dissipate heat. I havn't run it for long periods yet. It is too big to fin in any of my window mounts, so I will need another camera for that. There is a pretty good learning curve to the FX1. I actually read the manual.

Downsides are:
1. It is slow to focus, but filming storms, I will leave it on ifinity anyway.
2. White balance outside is a little off. It seems a little blue most times. It isn't hard to program 2 seperate white balance settings and switch to them for use.
3. It has no memory stick to take stills off of the video. Computer requirements are way beyond my computers capacity to get good video captures. I tried to get frame grabs, but the fram displayed on the computer isn't the same as the one on camera. I couldn't get the frame I wanted. This is probably due to the fact that my computer is only half of the minimum requirement for the software.

 

[Dan Robinson]

The sensor size on all of the HDV cameras except for the Canon XL-H1 are native 1440x1080 at a 16x9 aspect ratio. Meaning that the sensor pixels are squares, but the effective pixels are 16x9 (rectangular) and the image is always stretched a little horizontally for playback on HDTVs and the LCD. After you grab a frame you have to use Photoshop or Paint Shop to resize it to 1920x1080 and then it will be the correct proportions. Threads at DVInfo.net can explain this better but I think the reason is that a full 1920x1080 sensor is overkill because it has more pixels than the HDV format can support. The only reason the Canon has a full-size sensor is because it has the full-res HD-SDI outputs that can feed into high-end decks and switchers. The Canon's tape mechanism still records HDV like the others.

As for the lightning, I believe the HC1's behavior with the split-screen bolts is due to the CMOS sensor and the 'rolling shutter' scan employed. The FX1 doesn't do this because it is using conventional CCDs. However, all the HDV cams suffer from codec overload when you go from bright image to dark and back in single frame increments. As a result, some nighttime lightning frame grabs tend to have a lot of artifacting. Not much of a problem with daylight lightning. Either way, it's not an issue with playback since you don't really see the artifacts uless you freeze the video or slow it down.