Cal Club Autocross Forums

Data and video recorded with DIVA HD from ChaseCam

http://www.youtube.com/watch?v=2jaBa4RPtl8&hd=1" onclick="window.open(this.href);return false;

Funny thing, Corvetteonline said that this is the best video that they have seen, most of these videos are really wobbly, but these guys must have used a very good mount. Umm..no. We don't have the slow shutter speed issues found in cheaper cameras.

Dude could have picked up 4 mph if he didn't chicken out on the launch.


Hd sure does look good

slow shutter speed issues found in cheaper cameras.

In the cheap cameras I have to use at work we have the opposite problem. Fast shutter speeds which produces a chattery video look.

I sometimes add a Neutral Density or Pola filter to get a slower shutter speed, so that we get that smoother background.

Mako to wrote:
In the cheap cameras I have to use at work we have the opposite problem. Fast shutter speeds which produces a chattery video look.

I sometimes add a Neutral Density or Pola filter to get a slower shutter speed, so that we get that smoother background.

LOL. Physics disagrees with you.

Randy very cool, thanks for posting. Imgae is good but what I liked best was the sound quality.

Marshall Grice wrote:

Mako to wrote:
In the cheap cameras I have to use at work we have the opposite problem. Fast shutter speeds which produces a chattery video look.

I sometimes add a Neutral Density or Pola filter to get a slower shutter speed, so that we get that smoother background.

LOL. Physics disagrees with you.

Perhaps a little explanation the cheap camera has a static ISO, so "shutter speed" compensates to to maintain exposure. The higher ISO in bright light forces the shutter speed up. the ND or Polorizer will drop the effective speed between 1 - 3 stops. The result is the camera thinks it's darker and drops the shutter speed.

Though Randy spoke of shutter speed, I think he was using a common term in place of another phenomenon called "rolling shutter" where the camera reads image data off the sensor line-by-line so that by the time its read the last line, the scene has changed considerably since the first line. This is opposed to older CCD-based sensors that read the entire frame off in one shot.

Note that this is *not* "shutter speed" in the normal exposure-time sense.

Not all CMOS sensors have this effect, it depends on the data-output design. In the world of video-enabled DSLRs, the Nikon D90 was one of the worst offenders while my Canon T1i exhibits very little. I understand the higher-end Canons such as the 5D utilize a data-output port that is twice as wide as others in order to reduce the effect in that camera.

You can see it here strongly at 2:19:
http://www.youtube.com/watch?v=O8kvGoCoZkM" onclick="window.open(this.href);return false;

Or even in simple panning:
http://www.youtube.com/watch?v=MeXCRcmOK1A" onclick="window.open(this.href);return false;

Rolling shutter causes some pretty freaky effects with moving airplane propellers:
http://www.youtube.com/watch?v=S1oPiyXu-hY" onclick="window.open(this.href);return false;

Exactly. No need to get that technical.

Basically in the CMOS sensor world, by the time it scans, if it is too slow, the scene has shifted causing a "slow shutter" or "rolling shutter" effect. Or simply, the "jello effect." It makes the video look underwater and wobbly. I believe someone here once said they liked that effect because it made it look faster. ;)

We took great pains to make sure we did not have this.

Arthur Grant wrote:Randy very cool, thanks for posting. Imgae is good but what I liked best was the sound quality.

Thanks. One advantage of not having the microphone in the camera itself since I do not have to deal with the wind noise. You place the camera where you want without worrying about the sound.

Corvetteonline said it was some of the best sounding video also...

Creating the HD data and video recorder represents an amazing amount of work since it was all done here in SoCal (vs the imported stuff that the cheaper solutions use) and self funded. It was a large chunk of change (as in hundreds of thousands of dollars). So I am really pleased to see it finally in use. We are supposed to demonstrate to Top Gear UK and a few other tv shows. We sold 70+ systems to the FBI. All good news.

I look forward to the time soon when I can autocross again.

Sound is the best feature but lets not forget the no BS of having data. Your seeing the run, hearing the shifts, watching the distance run out and seeing the speed data.

We are supposed to demonstrate to Top Gear UK

Cool ... I work with the company, Extreme Facilities, that does all of the Top Gear UK car mounts.

Still spinning the tires at 150mph... that's my kind of fun.