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What ?i does my consumer camera shoot at?


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#1 David Silverstein

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Posted 06 December 2005 - 10:21 PM

Ive heard the term 60i and 24p but I was wondering hwat would be Panasonic 3 CCD Consumer camera shoot at.
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#2 Josh Bass

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Posted 07 December 2005 - 01:22 AM

I bet the farm it's 60i. Does the framerate look "movie-like" or like the news? new = 60i, movie-like = 24p.
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#3 David Mullen ASC

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Posted 07 December 2005 - 03:52 AM

Well, if it's a Panasonic NTSC consumer DV camera, and it's not the DVX100 series, then it shoots 60i.
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#4 Trevor Greenfield

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Posted 07 December 2005 - 05:37 PM

Most likely its from the GS series, the later models popular for their true 16:9 chips, but they are not 24p they are 60i.
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#5 David Silverstein

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Posted 08 December 2005 - 09:51 PM

yeah its got true 16:9 and its a gs series so its 60i. Thanks wasnt sure.
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#6 Ron_mc_Don

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Posted 18 December 2005 - 12:26 PM

Forgive my ignorance, but what is 60i and 24p?

Tony.
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#7 Freya Black

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Posted 18 December 2005 - 05:28 PM

Forgive my ignorance, but what is 60i and 24p?

Tony.


Field rates, kind of like frame rates only for video.

24p means 24 fields progressive
60i means 60 fields interlaced.

It's to do with how many pictures the camera takes in a second and whether the video is interlaced or not.

love

Freya
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#8 David Mullen ASC

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Posted 18 December 2005 - 09:47 PM

Field rates, kind of like frame rates only for video.

24p means 24 fields progressive
60i means 60 fields interlaced.

It's to do with how many pictures the camera takes in a second and whether the video is interlaced or not.

love

Freya


No, "24P" means 24 FRAMES per second, progressive-scan.
"60i" means 60 FIELDS per second, interlaced-scan.

Generally "P" rates are in frames per second, but "i" rates are in fields per second.

24P sometimes may be stored on tape as 60i (with a pulldown to convert 24 frames to 60 fields), or in the 24PsF format, where each frame is stored as two fields (same as 48i more or less.)

Since a frame of interlaced-scan video is made up of two fields, 60i is also 30 frames per second, but it is not 30P since it is not progressive-scan.

Edited by David Mullen, 18 December 2005 - 09:51 PM.

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#9 Ron_mc_Don

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Posted 19 December 2005 - 10:11 AM

So what's the difference between:
a frame and a field?
and progressive scan and interlaced scan?

And between progressive scan and interlaced scan, which is "better" for different occasions?

Thanks for your patience.

Tony.

Edited by Ron_mc_Don, 19 December 2005 - 10:15 AM.

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#10 David Mullen ASC

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Posted 19 December 2005 - 11:57 AM

For basic definitions of subjects, try searching on Google or Wikipedia:
http://en.wikipedia....rlaced_scanning
http://en.wikipedia....rogressive_scan

A field contains only every OTHER scan line of video and the next field contains the opposite / inbetween lines. The TV draws or scans one field onto the screen, one line at a time, from top to bottom, and then starts again at the top and draws the next field's lines, inbetween the first fields lines.

Most TV sets are interlaced-scan, especially older ones. Computer monitors are progressive-scan.

Generally an interlaced-scan camera & TV set are at high motion sampling rates, like 60 Hz (NTSC) or 50 Hz (PAL), which means the camera is taking a picture at 60 or 50 times per second, but each picture only consists of alternate lines, i.e. a field, and the next picture contains the inbetween lines.

Progressive-scan cameras tend to run at half that speed. The simplest way to think of it is if the camera now only samples motion 30 times per second, but each picture contains all the scan lines of a video frame. Now if this is a standard definition camera, it would probably store that as 60i by splitting each frame into two fields, so 30 becomes 60 for storage. But the difference in look between shooting at 30P instead of 60i is that the motion was only sampled 30 times per second, so it looks less smooth, strobier. On the other hand, there is more vertical resolution PER FRAME for moving objects because if you combine (deinterlace) the 60i capture to become defacto 30P, you'll notice that the moving object was in one position on every other line of video but had moved to a new position on the inbetween lines, so when combined, you get a "sawtooth" or "comb" effect along the edges of motion.

Since film cameras always capture an entire frame at a time, progressive-scan capture tends to look more film-like. Plus film cameras usually run at 24 fps or 25 fps for normal motion, so shooting at those frame rates in progressive-scan also replicates the strobier motion of film.

60i or 50i capture looks smoother, which accounts for the "live" immediate feeling that video has compared to film. Also a film camera has a shutter that is usually closed 50% of the time, whereas a 60i or 50i camera often shoots with the electronic shutter turned off, therefore at 1/60th or 1/50th of a second per frame but with no temporal "gaps" between images, unlike the light-dark-light rhythm of a film camera and projector. Again, the high sampling rate combined with the lack of temporal gaps (if no shutter is turned on) is what makes 60i or 50i capture look live, raw, immediate, whatever you wish to describe normal video.

It's not a question of "better" or "worse" although for certain post applications, it may be easier to work with progressive-scan images. More a question of look -- the classic interlaced-scan video look is associated with news, live events, soap operas, home videos, whereas the progressive-scan look is associated with film, and with subjects normally shot on film like dramatic narrative (fiction.)

Obviously over the decades, subjects like documentaries have been shot on both film and interlaced-scan video -- in fact, the news used to be shot on film. And there have been a few dramatic works shot for TV on interlaced-scan video cameras.

Edited by David Mullen, 19 December 2005 - 12:02 PM.

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#11 Ron_mc_Don

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Posted 19 December 2005 - 02:39 PM

Answered it perfectly. Thanks!
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