EX 50p footage in FCP - slow motion question

S

szornyeteg

New member
Hi,

I shot some footage at 720/50p assuming that when I edit it in a 25p sequence in FCP I'm going get a slow motion clip. Yet the clip plays back at normal speed. I tried to slow it down (time remap) thinking that "hidden" frames would reappear. Instead - of course - what I got was the standard frame blended slomo variety.

What am I doing wrong? How do I get 50p footage to play back 25p? And what does the 50p footage really mean - in FCP I see only 25 frames a second.

Any thoughts/help are appreciated.

Cheers,

Gyorgy Laszlo
 
Thanks, I'll try that - it may take some time before I report back since I've never used Cinema Tools before.

Thanks again.
 
Well, I did what VictorS suggested and it's just like he said, simple and fast. The only issue, that I didn't fully understand at the beginning, is that EX footage having a GOP structure you first have to convert it something that has all the frames - ProRes, Uncompressed, whatever. And when you bring that file into Cinema Tools you just click on "Conform", select the framerate and that's it. The conversion is instantenous, so I suspect that Cinema Tools only rewrites something in the original file "telling" it what it's true framerate is. But that's just my guess based on the observation that the original file gets overwritten and overwritten instantenously - so there seems to be no actual conversion process.
 
When you bring it into your FCP 25p timeline, right click on the track and change speed to 50%. Make sure you deselect frame blending. You dont need any other program to do this.
 
And for reference for straight up slo mo when you bring it into your timeline shoot 25 over 50.
 
50p is not the same as 50fps.

50p is not the same as 50fps.

Hi Gyorgy,

I think this is the answer to your question.

It's easy to confuse the video format 720/50p with the shutter speed of 50fps (frames per second). 720/50p refers to the scan rate of the video format you have set the camera to. 50 fps refers to the rate of the shutter. In your case, you set them both to 50 and so got normal speed and not slow motion.

If you want slo mo, you need to set the video format to 720/25p and the frame rate at 50 fps. (or anything between 26 and 50 actually). The shutter setting is under the first camera menu and is called "S & Q". Video format, oddly and irritatingly, is in the last "Other" menu.

Same goes for 24p and 30p. 720/30p with a frame rate of 60fps is slo mo. The EX1 won't do slow motion in the 50p and 60p formats, since the max shutter speed is 50 and 60 respectively. i hope that explains it.
 
Hi JVFANTE,

thanks for your reply, but IMHO you're completely wrong.

I think this is why: there is no such thing as a 50 fps shutter speed. Shutter speed is measured in seconds. So 50 fps is 50 frames per second no matter how you look at it. And when played back at 25 frames per second it gives you 1:2 slo mo. My original question was as to how to "force" a 50 fps clip to play back at 25 fps. For example this is how interlaced TV has been working for decades: in the PAL world you shoot 50 fps and play it back at 25 fps. It just so happens that you shoot 50 half frames (thus the interlacing or 50i) and TV electronics and NLE interpret two half frames as one.

jvfante said:
It's easy to confuse the video format 720/50p with the shutter speed of 50fps (frames per second). 720/50p refers to the scan rate of the video format you have set the camera to. 50 fps refers to the rate of the shutter. In your case, you set them both to 50 and so got normal speed and not slow motion.

...

Same goes for 24p and 30p. 720/30p with a frame rate of 60fps is slo mo. The EX1 won't do slow motion in the 50p and 60p formats, since the max shutter speed is 50 and 60 respectively. i hope that explains it.
Click to expand...

As for the last argument I think you're also wrong. In the traditional film world with a standard 180 degree shutter the shutter speed is always half of your frame rate. So 24 fps means a shutter speed of 1/48th second, 25 fps 1/50th, etc. If you shoot on film 50fps will automatically mean an exposure of 1/100th second. In the digital domain it is often the same, though not necessarily. While with film you need the "other half" to physically advance the film in the camera, a video camera does no such thing and so can shoot e.g. 50fps with a shutter speed of 1/50th second.

So I would strongly argue (and evidence points in that way too :)) that 50p played back at 25fps and 25p shot with S&Q at 50 fps played back at 25fps are exactly the same.

If you're not too angry for my criticism I still have a question however: I have just shot something today at 720/25p with S&Q at 32 fps and the resulting clips are painfully motion blurred. The playback speed is not the issue, but it looks like as if I didn't have 32 full, progressive frames but 32 full, somehow interpreted/predictec frames.

Does anybody have any experience with that? Is this the GOP structure wreaking havoc? Or am I doing something wrong?

Cheers,

Gyorgy

Anyhow thanks for your reply.
 
I shoot weddings most weekends and used to shoot 720P 25. However, when it came to slo mo for those romantic interlude segments, slowing the footage down in FCP to, say for example, 50%, the footage looked awful as there would only be 12.5 frames a second and the footage would look jerky.

I now shoot 720P50. When it comes to slo-mo, if I slow the footage down 50% in FCP, the footage flows absolutely fine, if half speed and of course no usable sound.

I could of course export to Motion and use Optical Flo, but with this type of work there really is no need.
 
50p is not the same as 50fps.

50p is not the same as 50fps.

Hi Gyorgy,

Let's see if I can clarify this thread so as not to confuse the issue. Some of this may be semantics of the terms shutter speed and exposure, but I do think that you are mixing up 50p and 50 fps. There is a difference. The former refers to the video format (720/50p) the latter refers to shutter speed (film or video). As you noted, the exposure is determined by the shutter ANGLE and the shutter speed.

What you (I assume) and all of us prefer is slow motion created in the camera and not in post, because it looks better because it is smoother. Simply put, you shoot 720/25p at 50 frames per second and you'll slow things by a factor of 2. In the US, make that 720/24p and 60 fps (shutter speed) and you'll get slightly slower motion. Basic stuff, really.

You have to remember that when you shoot in 720/50p with the EX1, there is no slow motion available. It's max shutter speed in this format is 50 frames per second, which is "normal" speed when played back in a 50p timeline. The camera even makes it obvious when you're "offspeed" as there won't be any audio recorded when it isn't shooting at a "normal" speed, for the given format selected.

Unless you alter their speed in post, each clip's video format determines what its "normal" playback speed is. So your example of 50p played back at 25fps is a POST process that will not look as smooth as a 25p shot at 50 fps. That's because there are more frames recorded in a given length of time.

Just remember that 50p is the video format and its normal shutter speed is 50fps. So, you might want to consider shooting in 25p, if you want to do the best quality slo mo in camera.

I hope that helps.

John
 
jvfante said:
Just remember that 50p is the video format and its normal shutter speed is 50fps. So, you might want to consider shooting in 25p, if you want to do the best quality slo mo in camera.
Click to expand...

Just be careful as you are confusing shutter speed / angle with fps. Overcranking (slow motion) is achieved by shooting 50fps over 25 (pal). The shutter speed remains independent - though when you are shooting it is recommended you double the shutter speed that you would normally use for 25fps. So, if you go for film look and usually shoot 25fps with a shutter speed of 1/50th then when you overcrank for slow motion your shutter speed should be close to double to achieve same look. 1/120th to 1/250th are usually good options for PAL or NTSC.
 
Noel,

You raise a good point.

In still photography, we often refer to exposure time as the shutter speed, but in film/video there is a slightly different meaning. Since the shutter is moving (in film) and electronically "moving" in video, "shutter speed", in MY experience, refers to the speed of the shutter, or frames per second.

Admittedly, it may sound like splitting hairs and can be confusing since we all see and speak of things differently. (Some say Petrol, and others say Gasoline)

To stay on topic of this thread, I've tried to explain the reason the OP didn't get slo mo when he shot 720/50p on the EX1. Judging from the amount of confusion in the replies, I think there's a good reason to try to correctly explain it so others can learn how to do slo mo.

I'm no expert, but I have muddled through the cryptic Sony menus like everyone else to get the camera to work for me. I hope some of this is helpful to others.

John
 
So how would one integrate it onto a 1080i timeline

I realise there would be uprezzing

Is this worth it

Shoot mainly at 1080i and change the settings when there is requirement for slomo

or just accept that if you want slomo the EX1 is a 720p/25 camera

What about integrating onto a 1080p timeline ?

none of the above clarifies in my newb eyes !

the SR12 handycam in burstmode (180FPS) just plays back in slo-mo with the normal footage - no messing at all

and what about getting 25% speed ie interpolating 50% speed - that would require the frame bland to be ticked or unticked !

SMM
 
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