60i question

[ryanschindler]

i don't really understand it i guess. i always though 24p was 24 fps and progressive, 30p was 30 fps and progressive and that 60i was 60fps and interlaced.

can someone break it down simple for me?

 

[Cassius]

The first two are fine. 60i isn't, though. It actually means 60 interlaced fields, which runs at 30 frames per second. But interlaced.

 

[ryanschindler]

thats what i never understood. is it better for slow motion? whats its purpose?

 

[andythefilmer]

Well technically no. It records 60 times a second, but it's 60 half frames per second. If you combined the 60 half frames, yes, it would be 30 frames per second.

 

[Cranky]

thats what i never understood. is it better for slow motion? whats its purpose?

Maybe the time has come to google it now? Or to go straight to Wikipedia.

 

[andythefilmer]

Well yes it would be better for slow motion because there is twice as much frames... I did a test once filming someone do an ollie on a skateboard in 30p and 60i then I slowed both them down to 30% and the 60i was MUCH smoother. I don't have the video anymore, but you should make a test and see what you like better.

 

[Cranky]

If you want to proper overcranking with 60i without interpolating or blending frames, you need to reduce speed either to 0.8x with dropping one field, or to 0.4x.

Here is a simple home video I made: http://www.vimeo.com/2431644

http://www.avchduser.com/articles/sony-vegas-overcranking.jsp

 

[pronghornproductions]

60I is better for fast paced action as you do not get judder on fast pans, if you are shooting action sports where both the subject and the camera are subject to alot of fast movement you are better off using 60i, 30p will work, but any fast motion will look stuttered and hand movement will seem magnified.

 

[ryanschindler]

how do you drop one field?
dosnt that just make it 30i?

 

[Cranky]

how do you drop one field?
dosnt that just make it 30i?

No, it makes it 30p. 30i is 60i.

 

[Barry_Green]

60i = 60 motion samples per second. But they are not recorded that way. That's too much information for the recording systems to handle, so they throw away half the information.

They throw away the even lines (0, 2, 4, 6) for one field, and the next field they throw away the odd lines.

In some ways it makes it easier to understand if we wouldn't call 480i "480/60i" and instead called it "240/60p". Because that's what it is. 240 lines, updated every 1/60th of a second.

But then, we'd still have to go into interlacing, because those 240 lines aren't all that goes into making up the picture. The system scans the even scan lines (0, 2, 4, 6, ... 476, 478) one time, then it scans the odd lines (1, 3, 5, 7, ... 477, 479) the next time, then back to the even, and then back to the odd. So it really is 240/60p, but the 240 lines are "interlaced" between the even and odd.

If that makes sense.