HMC40 & YouTube...

R

ravencr

Well-known member
Hello everyone,

I'm heading out on a 3 week shooting time, and the HMC40 and higher than consumer-tech video is new to me, including my HMC40. I shoot nearly all high speed action footage, and these next few weeks will be mostly shot with great sunlight a the dunes, desert, rock crawling, etc. I typically like to incorporate slow motion into my edited video, so my initial thought is to shoot in 720/60p. Is this the correct thinking? Or, should I be shooting in 1080/60i? I've been told that if shooting for slow motion, use a shutter speed of 1/120 in 720/60p, and 1/60 pretty much no matter what in 1080/60i. To me, based on my experience with my D300 still camera, those shutter speeds are only helpful if I'm wanting to blur the image slightly, or the wheels/tires spinning when panning, but is this different for a camcorder?

Then, my next question is what format to export using Adobe Premier CS4 for use primarily for youtube? I want the best format possible for the cleanest, best looking video on Youtube. Is there a format that YouTube won't compress, such as if I export using f4v or flv, for example? And, if so or not, what codec, bitrate, size, etc would you recommend for optimal playback on youtube?

Secondly, given the above, I'll also want to put this footage on DVD for my customers to use a sale/marketing pieces. Will this play a role as to what format to be shooting in, or do I just pick the best format for the web, then just output it the way it needs to be for the DVD after outputting the footage for the web?

Thanks in advance for the help...

Chris
 
First, let me start by saying I'm biased, I don't like interlaced video. With slow motion and freeze frame, each field has only 1/2 the number of scan lines. So, you are really getting 540 scan lines (in a field), when you shoot 1080/60i.

For the best slow motion, 720/60p is my choice. All the scan lines appear in every frame and you have plenty of frames per second to slow things down. So if you want to go to 50% speed, it still looks great and if you really want to push things, 25% speed can be done. It acts like 15 FPS, but you still get the feel of motion.

With 30p, 25% speed would equal 7.5 FPS and would appear to step through the movement.


Because you are coming from an HD master to an SD result on DVD, using 720p mode will do just fine. I find it hard to believe that going even higher to 1080/30p would improve the end result by much.


SHUTTER SPEED:

In an ideal world, our cameras would shoot and play back at around 300 FPS. IF the cameras operated that high, our eyes would see a true fluid motion, just like real life.

HOWEVER, technical limits make things less than ideal. At low frame rates, like 24p, the highest we want the shutter is about 1 / (frame rate x 2) = 1 / (24 FPS x 2) = 1/48 of a second.

Going to a higher shutter causes the image appear to strobe or pulse in the movement. The solution is to trick the eye into not seeing the slow frame rate. A shutter speed of 1/24 to 1/48 of a second has motion blur and helps keep the eye from seeing the steps in the movement. While 1/24 of a second gives the best blur, it also makes every movement fuzzy; so many use the speed of 1/48 of a second.

In general:

At 30P, the range in shutter speeds should be 1/30 to 1/60 of a second.

At 60p, the range of shutter speeds should be 1/60 to 1/120 of a second.

With interlaced (60i), we chose 1/60 of a second to help hide the interlace problem.


The logical question is, "Why have higher shutter speeds, like 1/2,000 of a second?"

As we move to the higher frame rates, the eye is less sensitive to the strobe or step like effect that we see in the lower frame rates. Thus, one can shoot at a higher shutter speed and be less likely to see this effect.

However, you want to look at test footage of 60p stuff at both 100%, 50%, and 25% speed to see what looks OK on your TV.


Bob Diaz
 
BobDiaz said:
First, let me start by saying I'm biased, I don't like interlaced video. With slow motion and freeze frame, each field has only 1/2 the number of scan lines. So, you are really getting 540 scan lines (in a field), when you shoot 1080/60i.

For the best slow motion, 720/60p is my choice. All the scan lines appear in every frame and you have plenty of frames per second to slow things down. So if you want to go to 50% speed, it still looks great and if you really want to push things, 25% speed can be done. It acts like 15 FPS, but you still get the feel of motion.

With 30p, 25% speed would equal 7.5 FPS and would appear to step through the movement.


Because you are coming from an HD master to an SD result on DVD, using 720p mode will do just fine. I find it hard to believe that going even higher to 1080/30p would improve the end result by much.


SHUTTER SPEED:

In an ideal world, our cameras would shoot and play back at around 300 FPS. IF the cameras operated that high, our eyes would see a true fluid motion, just like real life.

HOWEVER, technical limits make things less than ideal. At low frame rates, like 24p, the highest we want the shutter is about 1 / (frame rate x 2) = 1 / (24 FPS x 2) = 1/48 of a second.

Going to a higher shutter causes the image appear to strobe or pulse in the movement. The solution is to trick the eye into not seeing the slow frame rate. A shutter speed of 1/24 to 1/48 of a second has motion blur and helps keep the eye from seeing the steps in the movement. While 1/24 of a second gives the best blur, it also makes every movement fuzzy; so many use the speed of 1/48 of a second.

In general:

At 30P, the range in shutter speeds should be 1/30 to 1/60 of a second.

At 60p, the range of shutter speeds should be 1/60 to 1/120 of a second.

With interlaced (60i), we chose 1/60 of a second to help hide the interlace problem.


The logical question is, "Why have higher shutter speeds, like 1/2,000 of a second?"

As we move to the higher frame rates, the eye is less sensitive to the strobe or step like effect that we see in the lower frame rates. Thus, one can shoot at a higher shutter speed and be less likely to see this effect.

However, you want to look at test footage of 60p stuff at both 100%, 50%, and 25% speed to see what looks OK on your TV.


Bob Diaz
Click to expand...

I actually was testing this toinght, using 720/60P in both 1/30 and 1/60 - found this cause I was searcing for an answer.

I noticed in 1/60 I was getting strobing, in 1/30 I wasn't

HCM150
 
Awesome info Bob. That's exactly what I was looking for. Hal, am I understanding you in that when you chose the motion was jerky?

Chris
 
ravencr said:
Awesome info Bob. That's exactly what I was looking for. Hal, am I understanding you in that when you chose the motion was jerky?

Chris
Click to expand...

Yes, and that sort of surprised me and seems at odds with what Bob is saying. It was in lowlight but definitely strobing at 1/60, I could pan a lot faster at 1/30...

It was also indoors under a moving ceiling fan and "natural lights" just thinking to myself that this may have caused the strobing?
 
Last edited:
Yeah, that is such a slow shutter speed. I'm going to try 1/60 and 1/100 this next couple of weeks. http://www.zfhproductions.com says all his hd footage on his site is filmed with the HMC40 at 1/100 720/60p, and it looks sick...the best footage I've seen so far.

Chris
 
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
 
I hope you're right Bob...I'm planning on shooting between 1/60-1/120 out at Glamis...I'm hoping I get some great footage...but, I really need to find some ND filters quick! :)

Chris
 
You might want to do some test footage of traffic going down the road and some pans. Try it at 1/60 and 1/120 of a second with 720/60p to see what looks best to you.

ND Filters are very helpful if the F-Stop (T-Stop) wants to go above F8.

You may also want to consider a is a Polarizer Filter. This helps reduce some reflections and subject to conditions might make the colors richer. The light loss through the filter is around 1_1/3 stops. Prices range from around $20 UP.

As far as ND:

Neutral Density Factors

• ND.3 (exposure adjustment = 1 stop, reduces ISO 1/2)
• ND.6 (exposure adjustment = 2 stops, reduces ISO 1/4)
• ND.9 (exposure adjustment = 3 stops, reduces ISO 1/8)
• ND 1.8 (exposure adjustment = approx. 6 stops, transmits 1% of light,)
• ND 3.0 (exposure adjustment = 10 stops, transmits 0.1% of light)
• ND 4.0 (exposure adjustment = 13-2/3 stops, transmits 0.01% of light)
• ND 6.0 = (exposure adjustment = approx. 20 stops)
Click to expand...


Bob Diaz
 
Thanks Bob...the 3 places I looked only had the .3, .6, .9, and 1.8, so I went with the .6 and .9. I figured the 1.8 would be too much for a lackluster low light performer like the HMC, and I was worried I'd never use the .3, because it's too mild. BestI can tell from your help, Barry's, and many others I've read info from, I'm going to try those shutter speeds and dial the iris down as close to open as possible for what little bit of DOF I'll achieve with the HMC40. I'm so used to having tons of DOF with my D300, so we'll see how I do with the video camera now. :) Thanks to everyone for all the help...you've successfully helped me spend way too much money not only on equipment but overnight and 2-day shipping! :)

Chris
 
If you look at message #4 in this thread:

http://www.dvxuser.com/V6/showthread.php?t=182865

Barry Green
We've already discussed how the HMC40's neutral density filter works, automatically, to keep the camera's iris open as wide as possible for as long as possible, to prevent diffraction from happening. And as such, my recommendation is to keep the camera at f/6.4 or more open (i.e., use the range from OPEN on down to f/6.4, and I think it looks just fine even down to f/8, but try not to go past it into the range of f/10 or f/11, etc).
So what happens if you do stop down further? You lose some sharpness. How much? Well... not as much as I was thinking would happen, actually. There's a drop, especially at f/10.5 or f/11, but it's milder than I was expecting. (obviously it's nowhere near as bad as one would think, because of the nifty ND filter trick; it means that at a stated f/11 the camera's iris is really, truly, at around f/5.6, which minimizes the potential for diffraction to happen).

Diffraction-Combined.jpg
Click to expand...

I believe that Barry did this test at 1080p, so if you shoot at 720p, Diffraction is still an issue, BUT less of an issue than at 1080p. So going to F8 (T-8) or F10 (T-10) may not be as bad in the 720p mode. (My estimate based on calculations.)

If one is shooting in full sunlight, the rule of thumb is set the camera to F16 and the shutter speed to the ISO. So in the case of the HMC40, that would be about 1/60 of a second. Move down 3 stops (ND.9) F16 -> F11 -> F8 -> F5.6.

If you use a shutter speed of 1/30 of a second, 3 stops down would be F8.

If you use a shutter speed of 1/120 of a second, 3 stops down would be F4.

I want to point out that with lenses, wide open is the sharpest as far as resolution, BUT CA (Chroma Aberration) comes into play. Closing the lens 1 or 2 stops down reduces the CA. So the sweet point on the camera's lens may be around F2.8 to F8 (T8).

So both the ND.9 and ND.6 make sense for your choices.


Bob Diaz
 
Very cool Bob...thanks so much. Of course my decision to buy what I did was due to what was readily available, not all the science! :) But, that makes me feel better about the decision. I won't have the filters till this Tuesday, so I guess I'll shoot at 1/120th today to keep the F-stop as low as it will go, at least. I did some filming of the prop on the plane as I was flying into Yuma, AZ last night, and it was interesting that at 1/30th shutter, it looked the closest to what the eye saw, 1/60th was pretty accurate too, but a tad bit of aliasing, and then above that more and more aliasing occurred. I shot from 1/8th up to 1/2000th, so I can show people when I get back and am not on an aircard. It sounds like a nd filter above the .9 would have been helpful too to gain even more depth of field...oh well, maybe next time. I didn't think jumping all the way up to 1.8 was the right way to go either...seemed like too much light restriction then. I'll try to keep everyone posted on here the next couple of weeks, but unfortunately I won't be able to do footage online for at least 3 weeks.

Chris
 
get a medium (i have a .6) and a dark one (maybe .9?) and you can stack them if it's particularly bright. The only problem is if you stack too many filters they may become visible (vignetting)
 
I was wondering about that. I also wondered if it's smart to stack a nd filter and a polarizer, for example? When you stack your two filters, does it vignette?

Chris
 
The also make "thin" filters. Also known as "Wide Angle" filters. They are the same filters with thinner mounting rings. Downside is they tend to cost more.
 
Well, I'm hoping to finally shoot some footage today. Yesterday, we just rode all day and no filming. Today, I'm hoping to get some in, but the only filter I have is my tiffen uv filter, so I'm guessing the f-stop will be too high, we'll see.

Chris
 
you can always use bigger filters with a step-up ring if you're concerned about vignetting, however, they're harder to fit in some camera's lens hoods. I have a 52mm B+W .6 screwed on my panasonic gs500 (43mm) and it helps a lot, however, .6 isn't enough for strong daylight, .9 would be much better.
 
Yeah, I saw as high as F9 today in the direct sunlight...I'll be glad to have the filters on Tuesday.

Chris
 
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