cf24 vs cf25

omega

omega

Active member
just wondering why people are saying cf25 is better than cf24?

is it simply a resolution issue?

or is it an issue of 50i > 25p being handled better in camera than 60i > 24p?

or something else? i'm confused. i want to buy this camera eventually but i don't want to get the pal model and have to convert everything unless there is a good reason to do so.

i'd shoot 1080 60i and convert to 1080 24p or 720 24p if this works well. if anyone has done this, i would be interested in seeing/hearing about the results. thanks.

edit: sorry posted in the wrong place, can this be moved to the fx1 forum?
 
CF25 is better than CF24 for two primary reasons: motion rendition and resolution.

CF25 is, fundamentally, one field of video de-interlaced. It is a captured 1/50th of a second image, taken 25 times per second. It is lower in resolution than a full frame, but it is constant resolution, at a constant timebase.

CF24 is a weird mishmash of fields, resulting in two disturbing effects: first, the motion rendition is not even at all. For a given amount of motion, about 1/3 is allocated to one frame, and 2/3 to the other. The result is that a smoothly-moving object is not rendered smoothly, but has a herky-jerky start/stop quality to the motion.

The other effect is a shimmering/crawling vertical resolution issue. CF24 blends fields together in a weird way, so what happens is that for any given five-frame grouping of frames, two will have about 425 lines of resolution, two will have 475, and then the last one will have 575 lines. So as you're watching it, the entire image can have a pulse or shimmer to it; it's especially noticeable on a static shot of something with fine detail on it, like a stop sign in a street scene -- instead of being rendered static, it'll show a crawling/shimmering edge to it.

CF24, as a film simulation, is awful.

CF25 is better. CF25 is constant motion rendition and constant resolution. It has none of the drawbacks of CF24. However, it's not available on the US FX1 (but it is available on the US Z1). And for playback on an American TV, you'd have to slow the footage down 4%.

If you want an in-camera 24fps, the Sony is the only high-def camera that can't do it. The JVC offers genuine 24p, the XL1H offers a 24F mode that looks like it's as good or better than CF25, and the HVX offers genuine 24P in multiple resolutions.
 
Great Barry! In the name of this community (and not only!), thanks again for all this knowledge that you offer us. Of course, we'll be waiting to compare all the cams possibilities even if HVX is also already as effective purchase in my particular case. With CinePorter or FireStore will rock for docs stuff. My doubt, as you well know, is in terms of 35mm film-out @big screen... Anyway, as a Master that you are, you add always more info to our knowledge.

<PS> I appreciated very much that info regarding the XL-H1 lines test that you gave us here, if I didn't say nothing that's all because I'm waiting for other sources in order to post there my reply where I will beg you again your superior advice.
 
Wow, thanks for the detailed explanation Barry. That is exactly the answer I was looking for.

Looks like I will be shooting in 60i and de-interlacing.
 
You must log in or register to reply here.
Back
Top