Help! Me + HMC-40 = bad video today

[Chris Harding]

Hi Guys

That's not really moire with the picket fence but actually the vertical lines breaking up when you fast pan!! CMOS chips do that and there IS a warning about fast movement on the HMC40 brochure so it will be in the manual as well.
However in practice you would never pan that fast so I doubt whether it's worth worrying about!!
Moire doesn't come from the chip type but is quite common with all sensors. With my HMC72's a large brick wall got in the camera view and you can see the moire pattern clearly. And that's with CCD chips!!! Generally it's best to just avoid any surfaces with repetitive patterns!!!

Chris

[Chris Rademacher]

I often pan with fast moving vehicles as they pass by. Does this problem of aliasing or moire only exist when panning against repetitive looking static objects then? Or, should I try not to pan at all using the HMC40? Seems like that couldn't be the case.

Chris

[Sherri Nestico]

Well, I think with the picket fence I should have used a faster shutter speed. I didn't realize that in full auto the default shutter speed is 1/60. But the wavy lines on the green roof and the "blooming" effect from a striped shirt and a window with vertical blinds in other clips should NOT be happening at any shutter speed while I'm standing dead still. Like I've said before, I've owned a slew of camcorders in the last six years and this is the first one I've ever had these problems with. My Sony V1U is a cmos sensor and I've NEVER had problems with moire or blooming or vertical-line breakage. And the noise is not an AVCHD thing because my Sony HDR-SR-11 and HDR-XR500V handycams don't do it either.

I'm with Chris R. - why the heck would you want a videocamera you couldn't pan with? I mean, I go out to accident scenes, house fires, etc. I'm going to have to pan sometimes. I don't want to have to worry that I'm gonna get garbage footage from a $2,000 videocamera.

[Chris Rademacher]

I wonder if these problems can be adjusted out by altering some of the scene file items? I have no idea what most of them are, but I seem to remember reading that some of those items might be able to help.

As far as upping the shutter speed, it didn't appear to make a bit of difference in my videos. Does it seem like it did to you guys?

YouTube - Panasonic HMC40 Zoomed In Aliasing - Moire

Sherri, I wouldn't think the camcorder defaults on 1/60 shutter speed. I would think it would pick a combination of shutter and iris for optimal exposure automatically. I think if you're shooting in full auto and you switch over to manual, giving the brightness of what you're shooting, you'll see the shutter speed and iris be different given different conditions. But, I could be wrong too. I just think when I've switched from auto to manual before, I've looked at the gain, it it displays if it's applying any gain or not.

I discovered that while shooting with one overhead light, a max of 12db of gain isn't enough to expose properly. All my low light videos were shot at 24db, because I'm guessing the camera's sensor size isn't big enough to expose properly at low light. But, everyone's said this, which is another reason I'm guessing I won't need an nd filters for this camera in broad daylight either...I decided on just a uv filter and polarizing filter.

Chris

[Barry Green]

Just catching up on this but -- there's no aliasing or moire going on in that video. You're shooting at 1/2000 shutter speed! Of course that's going to make everything look stuttery -- you've removed all the motion blur.

You should *always* be using 1/60th when shooting 1080/60i. That's the only way you'll get natural motion rendition. The shutter speed should normally never be changed when using a video camera; the shutter is not used for controlling exposure. You use the iris, and ND filters, for controlling exposure.

The only times you change shutter speed are when you're going for a specific effect, such as the "Saving Private Ryan/Gladiator" effect, or streaky smeary blurring.

If you're shooting 24p, 1/50th is an appropriate shutter speed. If you're on 30p or 60i or 60p, 1/60th is the right shutter speed. If you're shooting 60p with the intention of using it as slow-mo footage, then you'd use 1/120.

Other than that, leave the shutter speed alone, if you want your motion footage to accurately convey motion.

[Chris Rademacher]

Originally Posted by Barry Green

Just catching up on this but -- there's no aliasing or moire going on in that video. You're shooting at 1/2000 shutter speed! Of course that's going to make everything look stuttery -- you've removed all the motion blur.

Only part of that video was shot using 1/2000 shutter speed. The rest was shot in auto...

You should *always* be using 1/60th when shooting 1080/60i. That's the only way you'll get natural motion rendition. The shutter speed should normally never be changed when using a video camera; the shutter is not used for controlling exposure. You use the iris, and ND filters, for controlling exposure.

Glad you said this, because that's not what I would have done, given my experience with still photography. Based on what you know about the HMC40's poor low light performance, in broad daylight, would you still recommend nd filters to allow me to turn the iris as close to open as possible for DOF? If so, what brand would you recommend? I've got the Tiffen polarizer and UV filters, but I didn't get any nd filters yet.

The only times you change shutter speed are when you're going for a specific effect, such as the "Saving Private Ryan/Gladiator" effect, or streaky smeary blurring.

I'm not sure I know what you're talking about with the Saving Private Ryan effect. To me, when shooting still photography of high speed action, I would raise my shutter speed, open up the aperture and freeze the motion, if desired. If I want the wheels/tires to look as if they're spinning, I'd lower the shutter speed to somewhere around 1/60-1/250th depending on how fast the vehicle was moving. Do the shutter speeds not correlate the same on a video camera, which is why they're so much lower?

If you're shooting 24p, 1/50th is an appropriate shutter speed. If you're on 30p or 60i or 60p, 1/60th is the right shutter speed. If you're shooting 60p with the intention of using it as slow-mo footage, then you'd use 1/120.

Barry, do you mind explaining for shooting high speed action footage, why I'd pick one setting over the other? I'm confused at the difference between 1080/60i and 720/60p. I definitely need to do slow motion clips of the footage I shoot, so my first inclination is to use 720/60p. But, why/when would I want to use 1080/60i or 24p in either 1080 or 720p? It seems to me I'd want the highest fps possible, so when slowing it down in Premier it looks fluid, rather than choppy. But, am I safe in assuming for TV everyone's using 24p, and how does effect the usefulness of the slow motion footage without looking bad?

Other than that, leave the shutter speed alone, if you want your motion footage to accurately convey motion.

So, based on your above information, is it safe to assume that if I dial open the iris, the camera isn't going to automatically change the shutter speed to properly expose...it's just going to overexpose it, right? So, in order to bring in the depth of field desired, I'd have to use nd filters to lower the camera's light input, which would allow me to open up the iris and achieve better DOF? Do you apply multiple nd filters at once, or just try to pick the best one for the situation, so having multiple ones is a must either way?

Thanks a ton for the help Barry...I would have had terrible footage and been really pissed. I look forward to your responses to the above...

Chris

[Denny Lajeunesse]

Originally Posted by Chris Rademacher

So, based on your above information, is it safe to assume that if I dial open the iris, the camera isn't going to automatically change the shutter speed to properly expose...it's just going to overexpose it, right? So, in order to bring in the depth of field desired, I'd have to use nd filters to lower the camera's light input, which would allow me to open up the iris and achieve better DOF? Do you apply multiple nd filters at once, or just try to pick the best one for the situation, so having multiple ones is a must either way?

Thanks a ton for the help Barry...I would have had terrible footage and been really pissed. I look forward to your responses to the above...

Chris

While in photography you increase shutter speed for a sharper capture of motion (less motion blur), in Video/Film you have to keep in mind that you are doing that at 24, 30 or 60 frames a second.

Yes, you add ND filters to keep your DoF (though a 1/4" chip is not going to be very shallow to begin with). In fact as Barry discovered the HMC40 does not actually close beyond 2.4 (correct Barry?) and actually slides in ND filters when you close the shutter more than 2.4.

This is not a common thing for a video camera. In fact it is the first time I have heard of it. It makes sense though as the 1/4" chip has crazy DoF (not shallow) and by sliding in ND filters it help keep what shallowness it does have. Make sense?

[Chris Rademacher]

Originally Posted by Denny Lajeunesse

While in photography you increase shutter speed for a sharper capture of motion (less motion blur), in Video/Film you have to keep in mind that you are doing that at 24, 30 or 60 frames a second.

Yes, you add ND filters to keep your DoF (though a 1/4" chip is not going to be very shallow to begin with). In fact as Barry discovered the HMC40 does not actually close beyond 2.4 (correct Barry?) and actually slides in ND filters when you close the shutter more than 2.4.

This is not a common thing for a video camera. In fact it is the first time I have heard of it. It makes sense though as the 1/4" chip has crazy DoF (not shallow) and by sliding in ND filters it help keep what shallowness it does have. Make sense?

So, does that mean, I shouldn't bother with ND filters then if the camera already builds it in when I slide the iris below 2.4? That doesn't make sense to me, because when I do slide it below the image is still getting brighter, which if the electronic nd filter is implied it wouldn't be, right?

In regards to the shutter speed, so is it better then to have the lowest possible shutter speed possible to stop the motion, but no higher, since it's processing it so often? Any higher and I'm only hurting the video quality because it's so processor intensive?

Chris

Chris

[Barry Green]

Originally Posted by Chris Rademacher

Based on what you know about the HMC40's poor low light performance, in broad daylight, would you still recommend nd filters to allow me to turn the iris as close to open as possible for DOF?

Unquestionably.

If so, what brand would you recommend?

The best you can. I usually recommend Heliopan or B+W.

I'm not sure I know what you're talking about with the Saving Private Ryan effect.

Staccato, unnatural motion. They used it in the beach-storming scene in SPR, the zombies in "28 Days Later" did it, "Gladiator" did it. It was a look that was really in vogue for a while, but I don't notice it that much anymore.

To me, when shooting still photography of high speed action, I would raise my shutter speed, open up the aperture and freeze the motion, if desired. If I want the wheels/tires to look as if they're spinning, I'd lower the shutter speed to somewhere around 1/60-1/250th depending on how fast the vehicle was moving. Do the shutter speeds not correlate the same on a video camera, which is why they're so much lower?

That's exactly how it works on video too. But, it's just not that common to do it. Video is about motion, not frozen motion. If you want to make a choppy/stuttery/staccato look (such as the aforementioned SPR look) then yes, you can experiment with the shutter and do that. But in general, for video purposes, we just don't mess with the shutter at all, it gets stuck on 1/60 and you control exposure through the aperture and ND filters.

Barry, do you mind explaining for shooting high speed action footage, why I'd pick one setting over the other? I'm confused at the difference between 1080/60i and 720/60p. I definitely need to do slow motion clips of the footage I shoot, so my first inclination is to use 720/60p. But, why/when would I want to use 1080/60i or 24p in either 1080 or 720p?

Progressive is always better than interlaced for slow-motion or freeze-frame purposes. 720/60p is ideal for capturing action and for slowing it down in post.

1080/24p has more detail than 720/24p, 1080/30p has more detail than 720/30p, but 1080/60i and 720/60p are about comparable; the additional temporal resolution of 720/60p makes up for the additional spatial resolution of 1080/60i. However, the advantages of progressive over interlaced make 720/60p my choice for live-action or to-be-slow-mo'd footage.

It seems to me I'd want the highest fps possible, so when slowing it down in Premier it looks fluid, rather than choppy.

Definitely.

But, am I safe in assuming for TV everyone's using 24p, and how does effect the usefulness of the slow motion footage without looking bad?

"live" TV is shot at 60i or 60p. 24p is for the "film" look. Slowing down 24p is awful, you pretty much don't want to do that. If you know you're going to want something slowed down after the fact, you're infinitely better off shooting that section in 60p.

So, based on your above information, is it safe to assume that if I dial open the iris, the camera isn't going to automatically change the shutter speed to properly expose...it's just going to overexpose it, right?

Correct -- when in manual mode. In full auto mode it might jiggle the shutter speed, but in manual mode it will never change the shutter on you.

So, in order to bring in the depth of field desired, I'd have to use nd filters to lower the camera's light input, which would allow me to open up the iris and achieve better DOF?

In theory, yes -- but in reality, you're dealing with 1/4" chips, and it's going to be nigh unto impossible to get any real shallow depth of field out of it.

Do you apply multiple nd filters at once, or just try to pick the best one for the situation, so having multiple ones is a must either way?

I would always want to use one filter. Stacking filters can cause a color cast in your image.

[Barry Green]

Originally Posted by Denny Lajeunesse

In fact as Barry discovered the HMC40 does not actually close beyond 2.4 (correct Barry?) and actually slides in ND filters when you close the shutter more than 2.4.

Sort of. The iris will stop down from wide open to about f/2.4 (I think... don't have the notes in front of me). Then, if you continue telling the camera to stop down the iris, it won't -- instead, the ND filter slides in, gradually. Then once you've stopped down far enough that the ND filter is fully in place (which I think is about f/6.4), any further closing of the iris wheel will actually start moving the iris blades again.

This is not a common thing for a video camera. In fact it is the first time I have heard of it. It makes sense though as the 1/4" chip has crazy DoF (not shallow) and by sliding in ND filters it help keep what shallowness it does have. Make sense?

It appears to be common for the tiny-chip HD camcorders, but I've never seen anything like this on 1/3" or above.

It's not so much for DOF, it's to avoid diffraction. Tiny-chip HD cameras are far more prone to diffraction issues than larger-chip cameras are. On a 1/3" you could see diffraction as early as F/4 in the red wavelength, and an HVX200 would have some serious resolution loss at f/11 because of diffraction. The HMC40 has much smaller chips, and 4x as many pixels, making it *very* susceptible to diffraction. So, this system keeps the iris open as much as possible for as long as possible, helping to avoid the territory where diffraction sets in and starts to overly soften the picture.

The downside is, you will likely never know what your true f-stop is. Think of it more like t-stops; the amount of light being transmitted is changing, even if the actual f-stop isn't mechanically changing for that two-and-a-half stop range.

[Barry Green]

Originally Posted by Chris Rademacher

So, does that mean, I shouldn't bother with ND filters then if the camera already builds it in when I slide the iris below 2.4?

You'll probably still need an external filter; the built-in one only goes to about 2.5 stops or so.

In regards to the shutter speed, so is it better then to have the lowest possible shutter speed possible to stop the motion, but no higher, since it's processing it so often? Any higher and I'm only hurting the video quality because it's so processor intensive?

Using a higher shutter speed causes unnatural staccato motion. There's not necessarily anything "wrong" with that, it's just ... not what's done. It's a different look. It looks choppy. It doesn't flow, like we're used to video moving. Video (and film) have a natural motion blur, using a higher shutter speed eliminates that blur. Instead of feeling like continuous motion, you instead get the feeling you're watching a bunch of still frames.

Use it for artistic purposes if you want, just do so on purpose, knowing that you're diverging from the typical motion look.

[Denny Lajeunesse]

It should be noted that a lot of sports tends to be shot at 120 shutter. I have tried that on a HMC150 set at 720 60p 120 shutter and find I prefer the look of the shutter off (well actually 60 when at 60P).

I found 60P be good for showing legs running (as apposes to legs moving in blur) and not overly choppy.

We're shooting Football at night and Hockey. 60P is what looks best for us at the moment, especially for hockey. I'm still testing for football.

It might depend on the sport. With Hockey the puck can appear to leap across the rink when at a higher shutter. You need a bit of blur just to keep track of the puck (to much blur say 30P and it looks weird).

High shutter speeds are like watching TV through a fan. As the blades spin by, temporarily blacking your view several times a second, they give the picture a staccato effect simular to what Barry mentioned.

[Chris Rademacher]

You guys rock. I'm going to experiment with 1/60 and 1/120 shutter to see what looks best with the hmc40. I really appreciate all the help guys.

Chris

[Chris Rademacher]

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

YouTube - MCX-USA RZR Turbo Kit Customer Testimonial - Greg

YouTube - MCX-USA RZR-S Turbo Kit Customer Testimonial - Cliff

YouTube - MCX-USA RZR-S Turbo Kit Customer Testimonial - Doug

YouTube - MCX-USA Prowler XTZ 1000 Turbo Kit Customer Testimonial - Jose

YouTube - MCX-USA RZR Turbo Kit Customer Testimonial - Gary

YouTube - MCX-USA RZR-S Turbo Kit Customer Testimonial - Brenda

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

[Chris Rademacher]

YouTube - HCR Racing UTV and Side by Side Long Travel Kits in Action

This was shot with the HMC40 in PH720/60P using the Panasonic .7x Wide Angle Lens and no nd filters all shot on a Matthews M25 Tripod. Sound was captured using the rode videomic with dead cat.

Chris