Recording Format Opinions

[Ron Evans]

Originally Posted by Perrone Ford

I am COMPETELY unsure why you'd use 1/30th on 30p footage. I don't normally use a 360 degree shutter. I use a 180 degree shutter which would put me a 1/60 for 30p (and 60i since are both drawing the same frame over the same period of time).

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60i and 30p do not use the same frame. For 60i the camera is actually shooting at 60 frames a second but only recording/transmitting a field of each frame. Arithmetically 60 fields are 30 frames which is where the confusion arises since the time code is based on frames so would be the same for both. Unfortunately the two consecutive fields of 60i do not belong to the same frame. 60i is not 30P transmitted field at a time, its more like 60P with half the vertical information missing, alternating odd and even fields for the 60 frames. Each field is 1/60 sec apart in time. So one would use as default 1/30 for 30P and 1/60 for 60i. Low cost de interlacing creates lots of artifacts because it ignores the fact that the fields are displaced 1/60 second. More complex deinterlacing interpolates the lost information over many frames to get a smooth deinterlaced image.

Ron Evans

[Perrone Ford]

Originally Posted by Ron Evans

So one would use as default 1/30 for 30P and 1/60 for 60i.

Ron,

Do you use 1/24 for 24p? Because I use 1/48th shutter for 24p to simulate a 180degree shutter, and I use 1/60 for 30p. I also use 1/60th for 60i.

[Ron Evans]

No I don't use 24P or 30P I don't like the motion and use 60i or 60P. You can use any shutter speed shorter than the frame rate. It will just change the motion blur on each frame. The faster the shutter speed the less motion blur. I would think the 1/48 would be correct for 24P since going faster would exaggerate the already motion judder. Same for 30P. 60i has the advantage of being able to use really fast shutter speeds without a noticeable visual effect and the newer deinterlacers in 120hz ooor 240hz LCD's can take advantage of the images to produce a clean smooth image.
Ron Evans

[Gary Griffiths]

Originally Posted by Ron Evans

60i has the advantage of being able to use really fast shutter speeds without a noticeable visual effect and the newer deinterlacers in 120hz ooor 240hz LCD's can take advantage of the images to produce a clean smooth image.

Good info Ron. Thanks for posting on this.

Gary