Slow mo at 720 60p with 7D?
 

Guys, I read a claim that slow mo can be done with the 7D at 720 50/60p. From what I know, 7D does not have native overcranking functions. The only way I see is to record in 50P and play back in 30p or 24p to "slow down" natively from the cam.

Pls enlighten me if I'm wrong. Thanks!

Switch the camera into NTSC from the menu and you can then shoot 60p 1280 x 720

Then use cinema tools (Mac only - not sure what the software is on a PC) to conform the 50 or 60p to 24 or 25p.

That is true slow motion.

Example: Every frame from 1 second of 50p gets matched to frames in 25p - So 50 frames becomes 2 seconds.

Hope that makes sense.

I use sony vegas, and all you have you have to do is right click the video clip, select properties and set footage to ".400". Which will make the 60fps footage, run at the speed of 24fps.

Yes, you are correct - the Canon 7D does not overcrank. Indeed, it's done by sampling at its higher frame rate and playing it back at a lower time rate within the NLE.

Michael

Um......what do you think 'overcranking' is in the digital world? It shoots at 50 / 60p - just the same as any other camera that shoots at 50 / 60p.

True. However, it doesn't mark the file for 24p playback. When you play it back in the camera or NLE, it plays at full speed. You need to manually slow it down in the NLE.

Of course, the end result is the same. You just can't review the footage in the camera in slow mo.

Sorta like film. You've got to play it back at the standard speed after it's been shot at a faster speed, otherwise it wouldn't be slomo.

On the 7D? You can play it back in slow motion - in the playback options to the right of 'play' is 'slow motion'.

Also - on a Mac you can batch conform all the movies into 24p using cinema tools. So they do playback as 24p.

Cool. I didn't know that. So the only thing missing is the ability to set the file header to 24p in the camera. That's pretty minor.

thaz cool Logan. I didnt know we can watch in slow mo. I felt that a true overcranking camera is one that allows me to watch the footage natively in slow mo like the XDCAM EX series but this is interesting.

Just to push this further.. No way for the undercranking rite?

There is a difference in some cameras like the Sony EX series where the data-rate actually doubles when you over crank so each frame has as much information as a normal 30p frame even if you over crank to 60 fps at 30p. This makes for very clean over crank.

Wow, that really helps a lot, thanks!!

Yeah - it took me awhile to notice the slow mo playback. Coming from the 5D it's just one of those menus that you don't pay much attention to.

you can do it in final cut that way too, it's just better with cinema tools because you can do 23.976

interesting!! So how do we get Vegas do to do exactly 23.976...?? I've never done this before!

In Vegas' properties box we can only input 3 digits. 60 to 23.976 would 0.3996. But we can only input 400 or 399?

??

If you start with 59.94, then a speed of 0.4 will give you 23.976.

In FCP if you change the speed setting it is just a regular video slow-mo and you're not using the additional captured frames. The only way to do it is to use cinema tools to change the playback frame rate.

Ohhhhhh, i'm an idiot, Thanks John - been out of the NTSC world for quite some time, completely forgot about actual frame rates while i was trying to figure this out!

Interesting. FWIW, in Vegas, when you slow down 60p to 24p for a 24p render, it shows all the frames. Vegas doesn't require that each timeline have a given framerate. In fact, the project framerate only matters for previewing the footage. All Vegas cares about are the original format, the rendering format, and the effects and transforms applied. It takes each clip at face value.

(I don't want an NLE war. I'm just being clear that you can simply slow the footage in Vegas and get the desired results.)

This is a rough edit of a few clips I shot the other day. All filmed at 720/50P and simply slowed down in Sony Vegas by 50%. I love that you can now film everything at 50P and only slow down what you want. Another plus is that 50P looks so silky at normal speed. Password: dvinfo

I'm not sure you're getting this Jon. Nothing has to be slowed down since it has been shot overcranked.

Some posters here are confusing a common video slow motion effect with an overcranked one - there's a major difference.

In Vegas, if you drop a 60p clip into the project, it will play in real time, unless the metadata says it's 24p, or if you tell it to slow down. (I don't own the 7D, but I assume that the metadata in the 60p clips say "60 fps".)

I'm not a Final Cut or Mac user, but I keep reading about time lines having a frame rate. That's a foreign concept for a Vegas user. And is it premiere that has to be restarted when you change project frame rates? These programs seem to approach video formats very differently.

The bottom line for Vegas is this: Put a 59.94p clip into your project. If it plays at real time, set it to play at a 0.400 rate. (Right-click the clip on the timeline and select properties.) It will play in slow motion at 23.976, one frame at a time as desired for an overcranked shot. In that menu, there is also an "undersample rate" that lets you skip frames, if desired. Set it to 0.500 and it will play every other frame.

The other half of this is to set your project to 23.976 so the edit preview is correct, and render to 23.976 to render as desired. On the other hand, you could set the project and render to 29.97 interlace and see traditional 3:2 pulldown of your 23.976p shots.

Again, I'm not claiming a "better than" or "worse than" situation. I'm just clarifying how Vegas handles framerates. Often I've seen people write about the FCP process as if it's gospel for all NLEs. (Vegas user probably do the same, though I'm not as sensitive to it.)

Jon, you can play different frame rates in FCP too, but that isn't what I'm talking about. I'll post an explanation later as I've got to run now...

Here's a wedding I shot with some 60P conformed to 24P mixed in. It looks great "overcranked".

Thats great footage mate!

Im a complete novice. If I shoot say a miniauture at 50p. The miniauture gets moved at double pace. When its played back at 25p it moves at my inteded pace and has more weight to it.

Why isnt this 'overcranking'? whats the difference between shooting at 50p and playing back at 24/5p with a 550d/7d and doing the same with a traditional film camera? (I understand that minautres are shot at a variety of frame rates the 7d cant do).

Why isnt this real overcranking?

Thanks
James

Appreciate it James!

I honestly couldn't tell you. I couldn't tell you the difference but all I know is I'm loving the 7D over my old 5dmk2 :).

No - if you shoot at the speed you watch, nothing will happen, it will appear normal. But if you shoot at twice the speed you watch then the footage will appear slowed down.

And, theory it is REAL over-cranking, just the digital equivalent. Over cranking came from old time camera operators who literally turned the crank faster, by hand. When it came time to project, at normal speed, the footage would appear slow.

If our intended playback speed is 24 and we shoot at 50 then we slowed down our footage! We, for all intended purposes, over-cranked in camera!

Hi Jon. It is also a good idea to disable resampling for that clip, so that Vegas does not try to create any new frames by interpolation or frame blending.

Richard

In FCP, when you drop in your 60p footage (59.94) into your 24p timeline (23.976), it will try to play at 24p but drop frames in the mix. If you slow down the clip to 40%, theoretically this should work out to be exactly the same rate, but it isn't. The clip will show 40% speed, but the velocity will change every 3 frames then every 2 frames from 50 to 33.3. It appears to be expecting some 3:2 cadence. Very odd.

You would think if you did the math (59.94 * .4 = 23.976) that FCP would play each frame appropriately. I had a clip that Cinema Tools conformed to 23.976 below a 59.94 clip in the timeline at 40% speed and the duration was off also. The conformed clip was a few frames longer (5;12 vs 5;08).

It seems the only way to use FCP without Cinema Tools is to open the clip in the viewer, change the speed to 40% and export as a quicktime movie from the viewer outside of the timeline. This brings the clip back in as 23.976 without any skipped frames, but adds another needless step to the workflow (unless you don't have Cinema Tools?). I exported as ProRes 720p24 and it came in just fine and at the same length of my clip conformed in Cinema Tools.

Whatever NLE you use, it's good practice to preview the output one frame time at a time. If you see frames repeat, skip ahead, or blend, you have problems.

Of course, if you are playing back 30p in real time in a 24p project or vice versa, you should expect to see time artifacts. But if you slow 60p or 30p down to 24p, you want to see nice clean frames.

Jon, we are discussing slow-motion here, not frame rate conversions; though related, they are different concepts. I know you understand the concepts but your explanations may confuse many people - if we are simply talking slow-motion, you can shoot 30fps and play back your footage perfectly smoothly in a 24p project, it will just take 25% longer to play than if you played it back at 30fps.

Overcranking, as correctly noted by Mike above, is a film term that has been in use for years. Indeed, when discussing overcranking or undercranking it is useful to think of how it is achieved with a film camera:

Imagine filming the second-hand of a clock; you set the camera to film at 100 fps and shoot for 10 seconds. You will end up with 1000 correctly exposed frames. Now you pop your film print in a projector and set it to run at 25fps, the clock will appear as though it is running 4x slower; it will take 40 seconds to move from frame 1 to frame 1000. Each frame will be perfectly clear and the movement of the second hand will be perfectly smooth.

Next you set your film camera to 25fps and shoot the clock for 10 seconds. Now you have 250 frames. If you play it in your projector at 25fps it will still take 10 seconds to play all 250 frames and the clock will appear normal.

Next, you import your 25fps footage into your NLE and drop it on a 25fps timeline. You add a motion effect so the clip plays at a rate of 25% (there are different ways to do this depending on your NLE), thus your 10 second clip will now take 40 seconds to play. You will notice that whilst the footage looks like slow motion there is blurring on the movement of the the second-hand or it appears to stutter. This is because your NLE has created extra frames by repeating or interpolating them. Of course, there are plug-ins that accomplish this very well, but the best way is to shoot enough frames in the first place.

On a 7D you can shoot at 50 or 60 fps and do a similar trick. But you must change the playback rate of the clip otherwise you are not using all the captured frames and you will simply be repeating and interpolating frames, which wholly defeats the object.

On different systems there are different ways to do this because they use different methods to handle the QuickTime wrapper. On Avid and FCP you'll have to use a program to change the playback rate contained in the wrapper (Cinema tools does this easily). It looks like Vegas has a very neat way to accomplish it as Jon has pointed out above, (though, the only thing I know about Vegas is there are more strip clubs there than in the whole of France).

My advice, test your workflow and check your output frames as Jon has mentioned looking carefully for repeated or blended frames.

It's very easy to handle overcranked clips in Edius, because it allows you to override the default frame rate of a clip. So you just set the 60fps clip to 24fps and it will play back as nice, smooth slomo. The more recent versions allow you to change the frame rate of multiple clips at once, which is more convenient than having to do them all individually.

Richard

Nicely explained, Liam.

hehe, it seems its easy on every NLE. Basically a prompt where you choose playback rate.

i'm assuming you didn't read Liam's explanation...

ya, i did...just wanted to be nice...in fact it seems like a bit of a PITA - where as the properties prompt in Vegas is pretty quick/easy to use.

we all get used to the equipment we use so in the end I guess it doesn't really matter

there have been a couple people who said that setting 60p to .4x will make it work exactly, but I use FCP so I don't know for sure

Ethan, you need to change playback rate in Cinema Tools before importing it into FCP. As mentioned in this thread, other NLE work differently, like Vegas and Edius, but in FCP if you do the slow-mo without going to Cinema Tools first, you are simply repeating frames.

Liam, I was just commenting on a post that apparently was deleted. It was in between my two comments. He asked about vegas.