How can I over/under crank to slo mo or fast look in XL2?

[Josh Bass]

Ah. I am illuminated.

[Dale Guthormsen]

Good evening,

This is a slightly older threadbut still of interest to many I am sure.

First, with an xl2 why would you Shoot interlaced and then deinterlace when you can shoot in progressive (30P)to start with.

Then go to a program like vegas which interpolates the frames to give you reasonable slow motion, definitely better than adobe (I use both) where it adds duplicate frames and will appear as slow motion.

The best slow motion effects I have seen is with the program Twixtor!!

I believe the new sony xd cam, ex 3 or such allows over and under cranking.

With most software you are building addative frames.

I personally shoot for slow motion and never shoot faster than 120th of a second and often prefer 1/60th. It makes for smoother movement and certainly more resembles slo mo from a film camera.

Would like to hear thoughts on this!!!

[Josh Bass]

They're saying that if you shoot in 60i and deinterlace later, you get 60 fields which can be converted to whole frames, giving you 60 fps, while shooting 30p in the first place will only yield 30 discreet frames.

[Dale Guthormsen]

Josh,

I am not sure I underestand this. If you converted the 60 1/2 interlaced frames to full frames it would still play at the desired 30/second (right?) and it would not run the 60 which would make it twice as slow if you could do that.

it would be cool if you could rebuild the half frames to accurate full frames and then run it at the normal 30 frames a second. If this is doable how and what software???


I am intrigued!!!!

[Josh Bass]

It seemed weird to me too.

Someone earlier in the thread posted this link. . .this is what I was referring to:

RAREVISION - New Media & Broadcast

Sometimes this stuff hurts my brain, but the idea is, I think, if you have 30 frames per second and turn it into 60, you essentially have two seconds worth of frames representing one second's worth of motion; in essence, slow motion. So yes, you play it back at regular speed. If you wanted it faster than 50% of the original speed, you'd speed up the 60fps footage to your liking.

[Michael Krumlauf]

The Canon XL2 can shoot overcrank, i have been doing it for a few years now. I actually shot a video today with it. Check it out.

YouTube - White Rain

[Josh Bass]

Can you explain? I have an XL2 and the only thing I know how to do (as far as slomo/overcrank) would be either the 60i method above, or shooting at a 1/250 or faster shutter and applying slo mo in post. If it shoots higher framerates than 30fps I'd be surprised to know about it.

[Michael Nistler]

Originally Posted by Josh Bass

Can you explain? I have an XL2 and the only thing I know how to do (as far as slomo/overcrank) would be either the 60i method above, or shooting at a 1/250 or faster shutter and applying slo mo in post. If it shoots higher framerates than 30fps I'd be surprised to know about it.

Josh,

Yes, you are correct. Technically, overcranking refers to the speed of the media across the lens system. It's not as though we can run a 60 minute digital tape through the camera faster than 60 minutes. So sometimes folks imply they're overcranking by varying the shutter speed and compensating in post, but that's not really overcranking the cameras motor.

Regards, Michael

[Josh Bass]

Thanks. I'd still like to know if the method in the article could be done in something like FCP.

[Cole McDonald]

Final cut method:

two duplicate layers of video (shot 60i) speeds set to 50% with no blending.

top layer has de-interlace filter applied (even fields or odd fields) and a blink filter set to 1.

If the footage ends up looking jumpy, switch the field order in the de-interlace

[Josh Bass]

Thanks! I will give this a try.

[Dale Guthormsen]

cole,

do I have this straight: shoot interlaced, import to track one. import and deinterlace same footage and add to track two, then time stretch or interpolate 50% morre frames.??

If that is the case what does the second track layer of deinterlacing actually do for the footage, as apposed to shooting progressive and then interpolating or time stretching 50%?

I use vegas and Pr Pro


thanks.

[Cole McDonald]

vegas and premiere I don't know...

The reason for the 60i footage is that it's a real collection of 60 images/sec... rather than 30/sec being stretched or guessed into 60. The drawback to this is that you lose half your resolution to get it... which if you're de-interlacing anyway happens regardless.

If shooting on a canon, shooting progressive loses 30% of the image anyway compared to shooting interlaced. But the promise of actual timeslices rather than created ones makes me happy.

The first piece of footage is imported, then speed adjusted to 50%. The second track is deinterlaced even and the bottom odd (I think I missed this part last time)... the blink filter reveals the lower clip every other frame (1/30 sec)... again if the result appears to flutter, the even/odd fields need to be reversed.

I think Vegas uses field deconstruction and de-interlacing to slow their footage down (could be wrong, but there's lots of threads on this forum on this subject - I'm in lots of them). Premiere, no idea.

[Dale Guthormsen]

Thank you cole,

I am going to tinker on this and see what I can get.


No one has ever totally explained the 30% loss to me, and I have asked several times.

If a ccd has full resolution and receives one full frame, how is that different from a full frame of interlaced?