24p questions

[Ryan Wachter]

Sorry for the repeat, i looked up jumpy and choppy and nothing came up so I threw this thread up there, thanks a lot of the response. I was hoping it was a due to the lcd.
Thanks again.

[Barry Green]

<<<-- Originally posted by Stephen van Vuuren : Barry:

While I had my DVX, I never did get around to film vs. video motion blur. Did you ever verify the amount of motion blur on identical shutter speeds on film vs. DVX?

I'm curious if there a differences in the motion blur characteristics between film and CCD's... -->>>

In general, side by side they look basically identical. However, I have identified one potential reason why the motion rendering might look fractionally different on a DVX vs. a film camera, and that's because of the way a film camera's rotating shutter works. However, not all cameras use a rotating shutter (some high-speed cameras use a prism, and the Eclair ACL uses a swinging-pendulum-type shutter, and you never hear complaints about its motion rendering) so I don't think there's much to be said there.

So, to repeat: there is no significant difference in motion rendering between them. There may be a tiny difference due to the nature of the film camera exposing the upper-left corner before exposing the lower-right corner, vs. the CCD exposing all at once, but it should be basically negligible.

[Stephen van Vuuren]

That's what I figured. During my brief period with the DVX, I felt the difference between it and film were not due to motion capture but just simply resolution, latitude and color. What's most impressive to me about the DVX100 is just how much better it's progressive mode looks than interlaced and how well it compares to HD progressive.

Juans experiment my really deliver the goods by leapfrogging the DV Codec.

[Paul Del Vecchio]

Can you ruin the 24p motion blur effect by choosing a fast shutter speed like 1/200? I dont have the camera but I'm saving up. Hopefully I'll have it in May/June.
Anyway, what about a shutter speed of 1/24. I was messing with the camera at B&H and 1/24 looks VERY jittery. (A little less jittery through the monitor). Anyway, I read a 1/50 (off) or 1/60 is a good setting but what would you use 1/24 for?
Sorry if it sounds like I dont know what I'm talking about.... frankly, it's cuz I don't. I'm new to this so I'm trying to learn.
Thanks everyone,
Paul

[Barry Green]

Shooting at 1/24 causes a lot of smearing but almost completely removes any trace of "jittering". Shooting at 1/200 would make the motion very choppy and "staccato" and would very much accentuate the strobiness.

I just gave a long-winded reply elsewhere, but basically the issue is that traditional video, i.e. 60-field-per-second video, is constantly "on" -- it's constantly capturing image. There's never a microsecond where the camera is "blind". 24-frame-per-second imaging (whether it's film, video, or high-def) is "blind" for fully 1/2 the time! It shoots a frame for 1/48 of a second, then closes the shutter and sits blind for the next 1/48 of a second, then shoots the next frame... it is this "blind spot" that makes the video look stroby -- exactly the same effect as a strobe light has on your vision.

If you shoot at 1/24, the camera would never be "blind", it would be recording all the time, and the results would certainly go a ways towards smoothing out the motion. However, you would also be sacrificing the very quality that makes 24P video look like film!

[Stephen van Vuuren]

Yeah, 1/24 is only useful on when you need low-light and don't have very much camera or subject motion.

[Paul Del Vecchio]

so would you guys agree that 1/50 or 1/60 is a good shutter speed in most normal shooting conditions? also, why use 1/60 or 1/50 when in essence, film's shutter is 1/48? Why not just manually adjust the dvx100(a)'s shutter to 1/48 all the time (if you are shooting movies and want the motion blur of films)?

[Bryan Roberts]

I've always been encouraged to set the shutter at 1/48 as it's the closest to a film cameras setup.....

[Barry Green]

Film cameras use all sorts of shutter angles. 180 degrees isn't necessarily standard. Some Super8 cameras had shutters as wide as 220 degrees. I've got a B&H Filmo that has a 216-degree shutter, a CP16 with a 156-degree shutter, and a 35mm Konvas with a 150-degree shutter. The Beaulieu 6008 had a standard shutter equivalent to 90 degrees, and an extended "low light" mode that was 144 degrees. CP16's came with 144, 156, or 170-degree shutters. Some cameras use 172.8 degrees.

Different shutter angles give different exposure times. A 180-degree shutter delivers 1/48 of a second. A 144-degree shutter delivers 1/60 of a second. A 172.8-degree shutter delivers 1/50 of a second. They're all common shutter angles, and all common film exposure times. They all look like film. So you can use 1/36 if you want, or 1/60, it'll still look like film, there's nothing magical about the 180-degree shutter. And I doubt anyone on earth could tell the difference between 1/48 and 1/50 (pulsing HMI's or fluorescents aside).

[Deniz Turkmen]

I've heard that when shooting 24p with the 100a, the image looks choppy in the LCD but will be fine when viewed with a monitor.

When I went to B & H the other day, I checked out the 100a and didn't notice any choppiness. However, the camera was not recording. Will I see choppiness only when it's recording? Is the choppiness present in the viewfinder, or only the LCD?

Just how choppy will the image appear. Since I'm directing a movie along with shooting it, I need to judge the actors performances through the camera, not on a monitor. I'm afraid choppy video will hinder my ability to accomplish this.

[Stephen van Vuuren]

Did you look at the LCD when the cam was in 24p mode? If so, the "chopiness" is the same to my eye when playing back.

It does not interfere with judging actors performance.

As a director myself, I might suggest Judith Weston's book on Directing Actors. Great book.

[Deniz Turkmen]

I looked through the LCD and the viewfinder. Neither looked choppy to me. Have you made a short or feature with the 100a? If so I'd appriciate any advice you could give me in regards to the camera.

I came real close to buying her book a few weeks ago but I was short on cash. I had read an article about the book in Moviemaker Magazine. It seems very helpful.

[Stephen van Vuuren]

Search around here for info. I don't currently have one, but most questions have already been asked/answered here.

[Stefan Scherperel]

It is true that more care needs to be taken when shooting hand held in 24p, however it can be done, and have great results to boot. The choppiness will only occur when your shutter speed exceeds the speed at which you pan or tilt, in other words, the faster the shutter, the more choppiness will occur in some objects. The things that appear the chopiest are high contrast areas, like a metalic pole against a bright background. This can be avoided in three ways. First, a slower shutter speed will give you more motion blur, thus causing the stuttering effect to dissapate. Second, panning a little slower will keep the stuttering effect from appearing. Third, (and also a technique which can be used with the first and second) is to have a subject that you are following in front of the stuttering background ie. a waiter walking through a restaurant to aid in panning from one table to another. This will cause the viewers eye to be fixed on the subject and not get caught into the visual loop that causes the stuttering effect. Follow these things and you can shoot handheld, upside down, panning, tilting, doing jumping jacks, or just on a normal tripod. Those who say that you must use this camera a stationary viewpoint either have not used the camera or have not taken enought time with the camera to understand how to use it effectively.

[Ryan Wachter]

Now I took that same footage and played it on a TV with the coaxle cables and its still all jittery. Maybe slightly less but still not a film look, its a strobic look. Any ideas?
Thanks
Ryan