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Old April 5th, 2008, 08:09 PM   #1
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Extreme audio spl causes dropped frames

I'm starting a season of drag racing videos and found a strange hiccup on my A1. Extreme sound pressure levels from Top Fuel and Alcohol dragsters causes dropped frames. I'm talking the kind of sound that goes right through earplugs and shakes your head/chest. When I started editing today, I first thought they were random dropped frames (and my FIRST experience with DF with my A1 through many tapes). What I noticed is that they are in the same location/time when the exhaust wave hits me. I had track access so I was right on the starting line about 8 feet from the engines. I'm taping in HD so it's a dozen frames at a time. . What I don't know if it's from audio overload (I don't think so right now) or just the sound shock wave vibrating the heads. I was using the on-board mic and also an EV ND257, and it happens either way.
I'll be shooting every weekend so I'll post again on my results, but I'm going to try some with no/low audio and see what happens.

Deaf Tom
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Old April 5th, 2008, 08:53 PM   #2
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I have a friend who shot in Africa behind and/or next to the muzzle blast while filming some hunting footage and had the same thing happen, only he was shooting SD with a Canon XL2.
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Old April 6th, 2008, 09:25 PM   #3
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Nitro noise

I guess it's kinda fitting my first post on this board regards drag racing, as I shoot the sport for a living with mostly prosumer level camcorders.

As to the problem of dropped frames it could be an old problem making a comeback. Back in the 90s with SVHS camcorders the concussion from the noise of nitro cars would actually bounce the tape off the head. There is also the issue of extreme output from the ignition systems. Both problems went away for me when I went to a a GL1 followed by a DV30. I have no experience with the A1, but either of those 'old' problems may well be the cause. Used to be the closer you were the worse it was. I can shoot as close a foot away. Best seat in the house.

I went to a JVC HD7 last year to get a 'feel' for HD before spending the big bucks on something better and shot all kinds of blown alcohol and nitro cars with the solid state sdhc card with no problems. Even in-car on a couple of supercharged door cars.

I found bracket cars would shut down the HD when up close, but I was still able to shoot nitro cars from about 100 ft down track with no problem onto the HD.

I'm waited for NAB before I update with both the A1 and the EX1 on my current short list. It would be nice to know if the Canon suffers when close to a very loud car.

Please keep us posted if you can.

Larry Pfister
http://www.horsepowerheaven.com
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Old April 7th, 2008, 07:50 AM   #4
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Would some type of sealed pressure resistant enclosure (e.g., underwater ) provide a bit of protection from the blast wave of the cars?
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Old April 7th, 2008, 10:29 AM   #5
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nitro noise

It could be worth a try, we used to pack small Hi8 cams in foam filled back packs for in-car shooting which helped.

Interesting part for me is that I've not heard of anybody having this problem for a good while. Many have been using the latest SD cams (of all makes GL1/2, VX2000 etc.) for years with no problems I'm aware of, now I hear of this on an A1 and I'm puzzled as to why.

Maybe the same reason why a dropout on an HD tape cam seems more severe than on an SD one. I don't know why that is either.

Larry
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Old April 7th, 2008, 01:05 PM   #6
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Out of about 25 close-up passes, I had 5 dropouts. Just funny how they happened at the loudest/closest point.
I have some 3/8" dead latex vibration absorbing sheet that I might try making a camera glove.
Larry you would be familiar with my other concern...the rubber dust that you come away covered in. I'm sure it's going to build up inside the heads and drive works after shooting, but I don't know how severe.
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Old April 7th, 2008, 03:46 PM   #7
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More Drag Racing

Quote:
Originally Posted by Tom Majeski View Post
Out of about 25 close-up passes, I had 5 dropouts. Just funny how they happened at the loudest/closest point.
I have some 3/8" dead latex vibration absorbing sheet that I might try making a camera glove.
Larry you would be familiar with my other concern...the rubber dust that you come away covered in. I'm sure it's going to build up inside the heads and drive works after shooting, but I don't know how severe.
Hi I'm new here, well been lurking for a few months.....

I'm glad to find that there are others here like my wife and I that are shooting video at our local drag strip, while we're not on the level of national events we do have our fair share of fast bracket cars.

This year we will be shooting with a A1 and a HV20 as a B roll camera, I'd be interested in hearing more of your experences and what we can expect from the A1 in this enviroment.

Tom, the problem with bracket cars is leaking from the ignition system? we will be on the starting line and this concerns me quite a bit if drop'd frames are going to be a issue.

Jon
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Old April 7th, 2008, 04:07 PM   #8
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Jon,
I'm not sure if t's spl or ignition noise. I assume alcohol dragsters have around 50-60kV magneto voltage, so that could be the cause. I'd like to share some video with you guys just to see other peoples editing style. I'm highlighting a couple local teams throughout the year while I try to do a weekend review at the local race track. I record in HD but my DVDs are SD as I found most people (racers) want SD.
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Old April 7th, 2008, 04:22 PM   #9
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rubber

Rubber is the bane of anybody on the starting line. Best to try and blow or lightly brush it off often as once it sets in you'll have fun rubbing it off. I wear nothing but black most of the time as I've ruined too many light colored shirts.

As to it getting inside on the heads, I never had that problem, and I would often have to quickly change tapes on the run. Best to try and do it back in the tower or somebody's trailer. I only ever used a head cleaning tape when I had problems...which was often with two old GL1s, but never with the DV30 Panasonic.

Larry
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Old April 7th, 2008, 04:37 PM   #10
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Quote:
Originally Posted by Tom Majeski View Post
Jon,
I'm not sure if t's spl or ignition noise. I assume alcohol dragsters have around 50-60kV magneto voltage, so that could be the cause. I'd like to share some video with you guys just to see other peoples editing style. I'm highlighting a couple local teams throughout the year while I try to do a weekend review at the local race track. I record in HD but my DVDs are SD as I found most people (racers) want SD.
Tom,

I'd be happy to share some of our video with you down the road once we get some editable footage, we've had so much rain in our area this year that our track was at one point under water....they have missed the opening day (5th) but should be open later this month. Like you we plan to shoot in HD and create the DVDs in SD, we are also the track photographers so it's going to be a very busy season.


Thanks for your time.

Jon
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Old April 7th, 2008, 05:16 PM   #11
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drag racing video

I guess this thread is kinda goin off course, but I have long had the idea of trying to bring together as many serious drag strip videographers as I can round up to do some kind of site.

I'm working some with 1320tv.com this year and know Susan Wade who runs it would love to get some more quality sportsman video. Would be worth your while to e-mail her and drop my name in this regard.

I do a lot of work for both Div 6 and 7 of NHRA for various projects and even though Glendora does not really recognize us such as they do with still shooters, I would like to work on trying to change that.

I have zero interest in shooting pro drag racing, as it's a zoo, and TV has it so wrapped up it's a joke. Fortunately I did all that back in the 70s and 80s as a still shooter when it was much more of a 'friendly' atmosphere. There's a ton of money to be made and fun to have at non-national event drag races.

Anyway, I have some pretty good contacts within the sport on the west coast and it's got to be to all our advantage to somehow, someday get something together to show we're serious and not just a bunch of Utoobers.

Larry Pfister
http://www.horsepowerheaven.com
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Old April 8th, 2008, 10:51 AM   #12
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Quote:
Originally Posted by Larry Pfister View Post
I guess this thread is kinda goin off course, but I have long had the idea of trying to bring together as many serious drag strip videographers as I can round up to do some kind of site.

I'm working some with 1320tv.com this year and know Susan Wade who runs it would love to get some more quality sportsman video. Would be worth your while to e-mail her and drop my name in this regard.

I do a lot of work for both Div 6 and 7 of NHRA for various projects and even though Glendora does not really recognize us such as they do with still shooters, I would like to work on trying to change that.

I have zero interest in shooting pro drag racing, as it's a zoo, and TV has it so wrapped up it's a joke. Fortunately I did all that back in the 70s and 80s as a still shooter when it was much more of a 'friendly' atmosphere. There's a ton of money to be made and fun to have at non-national event drag races.

Anyway, I have some pretty good contacts within the sport on the west coast and it's got to be to all our advantage to somehow, someday get something together to show we're serious and not just a bunch of Utoobers.

Larry Pfister
http://www.horsepowerheaven.com
Larry,

I know we're straying off topic a little, I looked at some of your work and I'm impressed for a one man show you do a great job, to try to get back on topic or close what type of camera are you using, Tom and I are both using a A1 as our main camera, if your using a A1 I'd be interested in your set up as far as presets or night shooting.

To stray off again (sorry Chris) later in the year when we have footage to share I may contact you about 1320tv it sounds like a very good idea.

Thanks.....

Jon
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Old May 4th, 2008, 08:34 AM   #13
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Did some more drag racing shots. For some reason my A1 was on SD instead of HD...don't know how, but discovered it after 1 tape so I left it there.
There were no dropouts, and I don't know if it was due to being in SD or not. However I found the the difference between shooting in SD, and shooting in HD and downconverting is really noticeable. Not as sharp and more prominant vertical scan lines.
The other thing is in the rush to get out the door, I forgot my mic. The A1 onboard mic performed pretty well when stuck in the subject's face for interviews.
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Old May 4th, 2008, 11:24 AM   #14
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I did a police recruitment video one time back in my Betacam days, with a BVW300. On the training range, I thought it would be cool for the cop to jump out from behind the building simulation and fire his .45 right over my head. It was a cool shot, but the concussion blew me over backward and there was a big dropout. At the time I figured the concussion caused the tape to lift off the head momentarily. (I still used the shot, with a cutaway at the instant of the dropout. By the way...don't try that without hearing protection. I was deaf for about an hour.)
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