HMC40 & YouTube...

BobDiaz said:
I'm doing a bit of head scratching trying to figure out why at 60p, 1/60 of a second shutter would show strobing and 1/30 would not.

Let's start with outdoor footage under sunlight. Sunlight does not flicker or flash, so I would expect that any action footage at 60p using a shutter speed from 1/60 ---> 1/120 of a second would look good.

With 30p, a shutter speed from 1/30 ---> 1/60 of a second should look good, but because of the lower frame rate, not be as smooth as the 60p footage.


With indoor shooting, AC LED Lights, Florescent Lights, and even Neon Lights, flash at 120 Hz (North America) or 100 Hz (Europe). The blinking is so fast, your eyes don't see it, but use a 1/60 of a second shutter speed in Europe and the risk of a pulsing light is very likely.


Hal2,

What is the frequency for the power in your area? Is it 50 Hz or 60 Hz?



Bob Diaz
Click to expand...

I'm in North America so it's 120 Hz -- like I said earlier I think it had something to do with the ceiling fan...

When I tried it again this weekend - same situation - no strobing :Drogar-Shock(DBG):
 
Denwa said:
How come they strobe at double the Power freq?
Click to expand...

Sine.jpg


30208.gif



For a 60 Hz input, there are 2 parts to the cycle: The first is a positive going wave. The second is a "negative" going wave. In reality there is no "negative wave", it's just the current flowing the reverse direction. However, in one cycle, an AC LED light or a florescent light has 2 bright peaks (one for the forward cycle and one for the reverse cycle).

Thus, 2 x 60 Hz = 120 Hz.


Bob Diaz
 
All of our power is AC, that means that the current moves on one direction and a split second later, changes direction, and moves the other direction. Thus the name AC (Alternating Current).

Now I know what you're thinking, "Why not just keep it going in the same direction all the time?" Well, batteries work that way and Thomas Edison felt that was the best way, but transformers don't work with DC (Direct Current). With DC, the electrical current always flows the the same way and is constant.

With AC, we can make use of transformers to increase or decrease the voltage. OK, WHY do we want to increase or decrease the voltage? Because all wire has resistance and over long power line runs, resistance is a bad thing. It causes power loses.

So, your local power company uses AC and transformers to increase the voltage to 17,000 volts (local neighborhoods) to even high voltages for longer runs.

Now, 17,000 volts is VERY deadly; even 1,700 volts would be very deadly, so the power company uses a transformer to drop the voltage down to 120 volts (USA), 220/240 (Europe); which is not 100% safe, but a lot safer than 17,000 volts.

Sorry, for the long answer, but the AC is needed to be able to bring the power to you home across any distance.


The power frequency is the number of times the current changes direction and returns back to the same direction again every second.


Bob Diaz
 
I'm confused...what does this have to do with strobing or aliasing again...I'm trying to upload videos as we speak. Here's a short one...very short terrible one really, but it was a buddy showing off the camera. :)

http://www.youtube.com/watch?v=MJUBRiMAQH0

Obviously this whopping 7 second clip doesn't show any traits of the camera...just my poor video skills. Hopefully this other one will be better...just drag races at the dunes. :)

Chris
 
Here's some testimonial videos I put up on Youtube from my Glamis, CA dune trip.

http://www.youtube.com/watch?v=Qyc89IN82pE

http://www.youtube.com/watch?v=R-aUlOnS7T4

http://www.youtube.com/watch?v=HkzfX98VHFc

http://www.youtube.com/watch?v=ZULzwt_ZHso

http://www.youtube.com/watch?v=ZTJukeFxu5w

http://www.youtube.com/watch?v=aPvrXO5Degg

All of this whipped together as one video for the SEMA show that just ended...all rough cuts, very little editing done to make them look more professional. I'm very impressed with the camera, and I've found that my matthews tripod when shooting today is a huge help. I'm shooting out in UT today and the next two days, and using the tripod makes all the difference in the world for quality shots. I played it through component out as 1080i, even though I shot it in 720/60p, and it looked outstanding on the television today. Unbelievable actually. The exposure was spot on, colors at +1 chroma look great. So far, I'm very pleased with the camera.

Chris
 
Here's a video I just completed:

http://www.youtube.com/watch?v=o4utezpM6s8

It was filmed using the HMC40 in PH720/60p with the following setup:

- Panasonic Wide Angle .7x Lens
- No ND Filters
- Rode Videomic with Dead Cat for Sound
- Matthews M25 Tripod
- OIS On
- Slow Motion is 25% of normal speed
- Edited with Adobe Premier CS4 on a Macbook Pro 17"
- Outputted using Mainconcept H.264 Youtube HD preset, but changed the fps to 59.94 from 24 fps.
- +1 Chroma

Any pointers, comments, or suggestions would be greatly appreciated.

Chris
 
the footage looks real clean mate, I also use premiere pro cs4, I just recently moved into the HD world, what did you find as the best way to capture your footage from the HMC-40 to work with Premiere Pro?
 
I've only tried a few different settings, but they all appear to edit just fine in premier cs4. I guess it all depends on what you're shooting and how you want it to look when completed.

Chris
 
Hey guys

Here's a quick vid I put together of my bachelor party weekend, mainly just to show you guys what 1080/24p looks like out of the camera. I shot it entirely in auto, and it picked a 1/50th shutter speed I believe most of the time. Keep in mind it's a home video, not edited much at all. :)

http://www.youtube.com/watch?v=cO-sg5UTzPQ

Chris
 
ravencr said:
Hey guys

Here's a quick vid I put together of my bachelor party weekend, mainly just to show you guys what 1080/24p looks like out of the camera. I shot it entirely in auto, and it picked a 1/50th shutter speed I believe most of the time. Keep in mind it's a home video, not edited much at all. :)

http://www.youtube.com/watch?v=cO-sg5UTzPQ

Chris
Click to expand...

Real nice Chris... I kept looking for the strippers, but didn't see 'em... hehe

The video looks great.
 
Yeah, what's funny is we were hiring our videographer for our wedding, and when I told him that I video'd the Bachelor party, he said "Are you crazy?" It was funny, because my fiance was sitting right there.

Chris
 
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