Motion and video

Buck Forester

Buck Forester

Well-known member
Okay, I've done lots of test shots with my EX1 and LOVE it! Most of it has been family stuff and chasing my boy around, handheld. As long as I have a subject I'm chasing, the footage is gorgeous and sharp.

I'll be doing mostly nature/wilderness stuff, lots of it on dolly/track and jib. I have noticed when using a dolly and rolling it slowly, using high DOF with foreground grass or flowers and a nice scenic background, the stationary grass/flowers loose sharpness. I want everything to remain crisp as I see on high-def broadcasting channels (unless I'm just not noticing it while watching them).

Admittedly I'm ignorant with video compared to still photography and I don't have other cameras to compare motion footage as explained above. Is this just how video captures motion? Is it Long GOP, and I-Frame doesn't have this problem? If so, I'll get the Convergent Design Nano Flash. But it may just be the physics of a moving camera against stationary objects, I wish I had other cameras to compare. For instance, viewing this forum page everthing is obviously sharp, but if I grab the scroll bar and move it up or down, the sharpness falls apart. Is this just the physics of motion and thus the nature of video? Sorry for the stupid question... gracias!
 
I've heard that the EX1 looks slightly better shooting 720 than 1080 because it's limited to 35mps. I'm not sure about "i" or "p" though. Heck, I don't even have an EX1 yet! :) (I'll hopefully be buying an EX3 setup this week)

Glad to hear you're not having any problems with the rolling shutter I hear so much about.
 
What's your shutter speed set to when dollying back? The only way I know of to get sharp individual still images from the EX1 (or any other video camera that's progressive scan) is to set the shutter speed fast enough as compared to the speed of the camera motion. Otherwise you get motion blur from a slow shutter. I got tremendously sharp still images at a horse show when I used a 22.5º shutter setting. Just about any frame made a nice, clear, printable image.
Speed up the shutter value and you should see sharper images. Of course, stop down the lens if differential focus is part of the problem.
 
if you are in bright light, you may be stopping your lens down too far - lenses are at their sharpest around the middle (say f5.6 or f8). Very small apertures can lead to lens diffraction, and loss of sharpness; different wavelengths will diffract different amounts (reds more than blues for instance).
 
Buck, you obviously are really good with 35mm cams..

Just like your 35mm cameras and soft images, it's all about frame / shutter rate and given motion with video cameras.

For giggles, try shooting some 720 60P 1/120 shutter and experimenting with faster shutter speeds.

Also, of course interlace will offer less motion blur than progressive.

I've had the EX1 right next to other cameras. The motion blur looks the same.
 
Gracias! Yes, I'm finding videography a LOT different in many regards than still photography. Obviously in still photography you're capturing a single moment in time, and exposure is in relation to shutter speed and aperture setting. 'Click' and you're done. You either got the moment or you didn't. In video you're capturing "time" itself, with all the fluid moments in a clip. Exposure is not so simple because shutter speed doesn't have anything to do with the exposure itself, it's more having to tweak the light with ND filters and iris settings. Getting a shallower or deeper DOF is not as simple as opening/closing up the aperture and having the shutter speed correspondingly changed. It's more of a balancing act with video. I don't have it nailed yet.

Focusing shallow DOF is much tougher too with video when the subject is moving... with photography you can simply click away and come out with a sharp shot even if only 1 out of 10 came out, you still got your shot. With video you can't continuously go in and out of focus and keep the clip. Much tougher. I really have a respect for skilled videographers.

With motion, I'm thinking what I'm seeing is just the physics of motion, just like scrolling this page the resolution of the text breaks up. It's still readable but it's not sharp when it's in motion. I'm not looking at "stills" from my video, I'm just looking at the footage when I do a slow horizontal dolly shot with stationary objects, not following them. They don't remain razor sharp with movement. I'll have to start watching more closely at footage on National Geo HD and Discovery HD to see if I only notice it on my own footage because I'm scrutinizing it more, ha!

This whole new world of high-def video is very exciting to work with and I can't wait to start editing and uploading some samples.
 
Buck, Here's a test you can do to verify whether it's your camera's exposure time blurring frames, or your monitor: pause the playback of the video and inspect a frame. Step through it frame by frame in areas where you noticed blurring. See if it's clear when paused. If this is the case, then it means the response time of the monitor is limiting you. If not, and paused frames are still blurred, you need to increase the shutter speed by reducing the dwell angle. For outdoor, sunlit early afternoon shooting, ND2 with 22.5º shutter gives you about f2.4, a good, sharp lens aperture. I find the lens sharpest between f1.9 and f5.6.
 
Thanks, basspig! I'll try that. Perhaps my question is even more 'general' than that, though. When you scroll on this page, even slowly, does the text look as sharp as when it's static? And if not, is this just the physics of motion?

Also, in your experience if you simply move the video camera 100% horizontally across, oh, let's say a bookshelf filled with books without turning the camera, keep it straight forward as you move sideways, is the text of the books as sharp in motion as when you're locked on a tripod? I'm not talking pauses or stills, but simply watching the video on your monitor. It's not for me, but if it is for you, then obviously I just need to learn more about tweaking settings. The issue I'm talking about is not about lens sharpness because the object is razor sharp until I start the motion. It's not like the object (or text in my bookcase example) breaks apart and turns into crap, it's just not as sharp as when I'm still.

In nature shots I want to keep foreground grasses stunningly razor sharp, full HD, the Wow! effect, as I pan or dolly horizontally in a wilderness scene. In distant objects it's fine because the movement is obviously not noticeable even if the camera is moving, but if it's only a few feet away it happens, I see it on my lcd viewer and my 30" ACD... I haven't hooked up my JVC DT-V24L1D yet, but it seems clear that movement is not as sharp as non-movement. I'm assuming this is all codecs and not just Long GOP, but I'm not sure.
 
Yes, text blurs when I scroll it. That's a function of the monitor's response time at turning pixels on and off.

To achieve sharp images in a scene like you describe, the dolly move must be slow and steady, maybe no more than 2-3 inches per second, and the shutter speed must be very fast. Of course, if it's fast enough to produce sharp images, you'll notice "frame judder" on a fast-responding monitor. But the images will be sharp. If the monitor is slow (>6mS) then you'll see some blurring until you pause the video.

So I would do this for your shot:

Focus foreground
Fast shutter, 22.5º or 11.25º
Slow dolly move, <3"/sec

Long GOP has nothing to do with it, I can attest from experience shooting fast-moving horses.
 
Thanks, basspig. I'm hoping to get razor sharp moving images with 'natural' movement, not juddery. I don't think I've ever turned on my shudder so I'll see what effect that does too. I'll also try your test suggestion as well. Thanks again.

As for shooting fast moving horses, I agree, I've never had any motion concerns at all when following a subject. I chase my boy around at high speeds handheld a lot and have never noticed any motion issues. I only see it when I move the camera and everything else stays still, even very s-l-o-w-l-y.
 
Hi Buck, If your shutter switch is off, then that's your problem. Turn it on and you'll be a lot happier with the results. In the off position you get something like twice the normal amount of motion blur (360 degress, I believe, vs. 180). 180 is "normal", and if you want to cut your shutter angle narrower for more sharpness of motion as Basspig suggested, just be wary of "judder" or strobing or the picket fence effect that will occur at some point. 180 is what we are used to watching on tv and in the movies. If you see the latest Spike Lee film, they use the Saving Sgt Ryan cut shutter effect of 45 or 90 degrees to give it that hyper real effect. Fine for certain scenes, but decidedly different from what we are accustomed to seeing.
 
Well I checked my shutter button and it's switched to "on" so I must've switched it on soon after I got it. Hmmmm.

I don't have time right now to do basspig's tests, but since I have my camera in hand I simply held up a piece of paper with text in front of me, well lit, and slowly moved the camera while keeping the paper still and the text loses sharpness upon movement. I can even see this in my lcd viewfinder live. This doesn't happen to you guys? The image stays razor sharp, the same as a still image, even when you move the camera and keep a subject (text on paper) stationary? I'm baffled why mine loses rez.
 
I have a shoot tomorrow afternoon. I'll do some tests while I have camera and lights setup.

-P

Buck Forester said:
Well I checked my shutter button and it's switched to "on" so I must've switched it on soon after I got it. Hmmmm.

I don't have time right now to do basspig's tests, but since I have my camera in hand I simply held up a piece of paper with text in front of me, well lit, and slowly moved the camera while keeping the paper still and the text loses sharpness upon movement. I can even see this in my lcd viewfinder live. This doesn't happen to you guys? The image stays razor sharp, the same as a still image, even when you move the camera and keep a subject (text on paper) stationary? I'm baffled why mine loses rez.
Click to expand...
 
One thing that may help is shooting a faster frame rate. 720p60 will give you the absolute best compromise between smoothness of motion and sharpness of the image. At that speed, you can crank up the shutter speed with very little 'jutter' and get crystal clear images.

Also, one thing I've noticed using the EX-1 is that the Fujinon lens on it really likes the more open apertures. I try to keep it at f8 or below (more open, that is). If you get close to f16 it will be very difficult to keep anything in focus. Fortunately, upping the shutter speed will have the side effect of needing a more open aperture.

Another thing I would recommend would be to stay away from interlace scanning. 720p60 actually gives you more apparent vertical resolution per frame than 1080i does, at no loss in temporal resolution. That is, the smoothness of motion that the interlace scanning gives is still there at 60p but you also get the benefit of progressive scan. A progressive image will always beat an interlace scan image of the same resolution in terms of sharpness whenever there is motion. This is one reason I like shooting in 24p when I am producing a DVD. DVD's can support 24p natively, and will look much better on a standard widescreen HDTV than a DVD shot at 30i (except some of the older projection or CRT models). The only downside to 24p is that it is less forgiving in terms of motion judder. It is easy to come out with an image that looks like it is strobing if you are not careful with panning speed and precise following of subjects. That's why the 720p60 mode works so well.

As for text, there are certain scrolling speeds for a given font size that will simply not look good no matter what. Generally, you have the choice of progressive scan text or interlace scan text. At the worst, interlace scan will have a "crawling" look to it, while progressive scan once again will look "juddery". I happen to prefer the progressive look to interlaced when it comes to text, and if I am producing an interlaced scan project 30p always works nicely. Since both fields of a frame define the exact same placement of the text, the progressive image will carry over even on interlaced scan monitors, and no frame rate conversion is required.

Hope that helps :)
 
Buck, It's all motion blur based on frame rate and shutter speed.
It's easy to test this by increasing shutter speed.

Also, do not trust what you see for motion played back via the EX LCD, and a lot of computer displays. I've noticed motion diffences even playing different sofware players on your computer.

Shoot somes tests at different frame rates and shutter speeds and burn them to Bluray or DVD and play them back on your normal home viewing system. This will give you a good idea of what to expect.
 
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Mark has really nailed it with a lot of complaints (regardless of the video camera used) on motion when viewed on your PC LCD screen. As Mark mentioned, just pause your video during playback on a scene that has motion. If that frame apears to clear up when stopped, this is due to the response time for your display.

Buck, like you mentioned regarding scrolling. For giggles, open one of your videos in VideoLan (or whatever your using). Do not fullscreen, keep it in a smaller window and have it paused. Now grab the title bar and drag it side to side. This particular laptop I'm using the video goes soft until you stop.

This is why I have been mentioning right along DO NOT trust movement on your PC, master your footage to a media such as BluRay or DVD (film if you have deep pockets! lol).
 
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Stevet, I haven't had time to do much thorough testing, but I did some basic tests a few minutes ago and changed shutter speeds.

I tried various settings (and my shutter is on). I tried 1080/60i/30p/24p and 720/60p/30p at the default shutter speed (such as 60 for 30p, etc.) and I tried 1080/30p at a faster shutter speed (250).

I used a row of books on a bookshelf as my test and slowly horizontally panned slowly across the book spines. The motion breaks up the sharpness noticeably. The best in my unscientific test was 720/60p, but it still wasn't good. Once I stop the camera everything is razor sharp... once I slowly pan it immediately loses sharpness. I viewed this on my 30" Apple Cinema Display... I haven't had time to determine if it's the monitor refresh rate and maybe the motion would stay sharp after going to blu-ray or whatever, but I'm not confident about that.

I'm HOPING this is Long Gop codec and NanoFlash will solve my problem. Motion on static subjects is my only concern here. I'm happy with the color and sharpness of stills (or even following a moving subject), but the visions I have in my mind of what I want to create on video defintely requires sharp rendering of motion on static foreground scenes. El periodo. It's definitely not a rolling shutter issue or anything. I have no idea if this happens on i-frame recording or not because I only see what I have. NanoFlash will give me either the option of i-frame or much higher Long Gop bit rates. I'm hoping one of these will solve it but I need to see some NanoFlash motion test footage first.

P.S. I haven't tried VideoLan (not sure what that is, but I'll Google it) or editing the footage, this is just straight out of the camera.
 
Buck...

Have you tried going through the material frame-by-frame to see if the image is sharp or blurred?

I saw a demo of an LCD that had a 120 Hz refresh rate. They had computer-generated crawling text on the screen going from right to left, and on the half with the 60 Hz refresh rate the text looked blurred. But when it got to the side with 120 Hz refresh rate, it looked clean.

So the original text was clean. But it displayed poorly on an LCD screen with a 60 Hz refresh rate.

it could be the monitor. The only way to know for sure is to slowly go through the material frame-by-frame and see if it's sharp or not.

Good luck!
 
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