mtheory Posted October 9, 2014 Share Posted October 9, 2014 For years there have been discussions about C300's video look, - I have always insisted that even the 5D had a more cinematic look than C500 after careful observation, and it wasn't just due to larger sensor, but it was apparent in the specific quality of the motion itself. After doing some reading of the C300 white paper from Canon I found this: "When the sensor is set for a 24 frame picture capture rate the readout of the optoelectronic transformation takes place at a high speed of 60 progressive frames per second. That significantly reduces the “rolling shutter†effect that is synonymous with CMOS image sensors. " http://learn.usa.canon.com/app/pdfs/white_papers/EOS_C300_New_35mm_CMOS_Sensor_WP.pdf This is confirmation that C cameras do not in fact use true 24p capture of moving subjects, but use the video 60p, then simply downscale to 24p internally. What this means is that while C camera satisfies the display standards of 24, 25 and 30 fps for broadcasters, the actual movement of actors or objects is faster than what our eyes are used to in the cinema, hence the image has the video quality regardless of lenses or codecs you use. I'm glad to finally have closure on this. The Panasonic DVX was a hit among indie filmmakers in the pre-5D era because of interchangeable lens adapters and a "True 24p" capture, which Canon camcorders never had. Canon simply ported that old tech into C's new housing. So even if the next C100/300/500 Mark II will have 4K and RAW it's pretty much dead to me as far as I'm concerned. RAW 4K video is still just...video. Quote Link to comment Share on other sites More sharing options...
andy lee Posted October 9, 2014 Share Posted October 9, 2014 its an interesting read that white papaer - nice find! it also says 25p and 30p use a similar process! I wonder how many DOPs who use C cameras on big movies know this ! at least Panasonic cameras say in the menu 24p is 24p and 25p is from a 50i sensor read out Canon make no mention of this anywhere but this white paper. PS: do you know if the 5D does this too? do ALL canon cameras do this is this their way of doing 24p on their whole range? Quote Link to comment Share on other sites More sharing options...
Guest Ebrahim Saadawi Posted October 9, 2014 Share Posted October 9, 2014 Then how can I set my shutter speed to 1/25s when shooting 25p on the C100/300? I never noticed anything off with the motion, it looks 24p to me. Quote Link to comment Share on other sites More sharing options...
hmcindie Posted October 10, 2014 Share Posted October 10, 2014 They are talking about rolling shutter dudes... I'm almost speechless now... Every single CMOS camera uses a different readout speed than what is recorded. The readout is just how fast the sensor gets read. 24p, 25p, it has nothing to do with the end result. And in that white paper it should say 1/60s readout speed, not fps. You do know that every single CMOS camera (except global shutter cameras) do this? So keep your horses in your stables. Quote Link to comment Share on other sites More sharing options...
andy lee Posted October 10, 2014 Share Posted October 10, 2014 thanks well thats good to know!! Quote Link to comment Share on other sites More sharing options...
mtheory Posted October 10, 2014 Author Share Posted October 10, 2014 I guess this explains why DVX100 was able to achieve true 24p, - because it used a CCD sensor instead of CMOS? And what is the variation of readout speeds between C300 and 5D for example? The 5D has more natural motion than C300 in my view. Quote Link to comment Share on other sites More sharing options...
MattH Posted October 10, 2014 Share Posted October 10, 2014 They are talking about rolling shutter dudes... I'm almost speechless now... Every single CMOS camera uses a different readout speed than what is recorded. The readout is just how fast the sensor gets read. 24p, 25p, it has nothing to do with the end result. And in that white paper it should say 1/60s readout speed, not fps. You do know that every single CMOS camera (except global shutter cameras) do this? So keep your horses in your stables. It says 60 frames per second, not 16 millisecond read out spead. 60 frames per second may equate to 16.66 ms readout, but its at 60fps not at 24fps. Iv'e always suspected that something like this happened. Think of how difficult it would be to get the sensor to start each frame at precise devisions of time for pure 24,25,30p etc. Not impossible, but much easier to read at 60fps all the time and only record some of the frames. The first and third of each 5 frames in the case of 24p. If this was played back at pure 24p timing, every second frame would be shown 1/120th of a second early. I can't tell you if that would be perceptible or not. I suspect I wouldn't be able to tell unless I trained to look for it. But since most people are viewing web material on 60hz monitors, the conversion back to 60hz may play the frames at the exact same timings they were recorded in. However I am not aware if a 24p video file gives any indication of which frame is which if it initially came from a 60p source. Maybe someone can enlighten me. But I would guess it doesn't. If not then there is a 50% chance that every second frame would be played 1/60th of a second late instead of 1/120th of a second late if it were a pure 24p. Again I couldn't tell you if this difference would be perceptible. Quote Link to comment Share on other sites More sharing options...
Administrators Andrew Reid Posted October 10, 2014 Administrators Share Posted October 10, 2014 They are talking about rolling shutter dudes... I'm almost speechless now... Every single CMOS camera uses a different readout speed than what is recorded. The readout is just how fast the sensor gets read. 24p, 25p, it has nothing to do with the end result. And in that white paper it should say 1/60s readout speed, not fps. You do know that every single CMOS camera (except global shutter cameras) do this? So keep your horses in your stables. No that's not right. Not every sensor does it. Some read at 24fps. Some read at 60fps. The C300 isn't doing true 24p. The sensor does 4K at 60fps, and Canon's image processor use this to deliver HD at 30fps/24fps. It was designed to do as clean 1080p as possible. 444 in fact. Although it's stored as 4:2:2. andy lee 1 Quote Link to comment Share on other sites More sharing options...
Administrators Andrew Reid Posted October 10, 2014 Administrators Share Posted October 10, 2014 It'd be good to have some examples of the difference it makes. For sample take Nikon D750 footage at 60p and convert it in post to 24p, then compare it to 24p straight from the camera. Quote Link to comment Share on other sites More sharing options...
Guest fe4a3f5e8381673ce80017d29a8375f1 Posted October 10, 2014 Share Posted October 10, 2014 How does motion blur work with regard to downconverting 60p in the C300? When you shoot 180 shutter at 24p. How can you get a 1/48s exposure if the sensor is grabbing images at 1/60s? Is it simulated in camera somehow (blending frames?)? mtheory 1 Quote Link to comment Share on other sites More sharing options...
jcs Posted October 10, 2014 Share Posted October 10, 2014 Sometimes I shoot at 60fps to have the option for slow motion in post. In cases where slomo isn't needed, I use 'drop-frame' from 60 to 24: just add a 60fps clip to a 24fps sequence. When played back with a suitable standalone player or real-time hardware (such as streaming to my Samsung HDTV), the resulting motion is butter smooth: no judder or discontinuous motion (beyond what film might do with panning). While there is some interframe variance going from 2.5x 60 to 24, it's not really noticeable. 120fps provides perfect 24fps sampling- take every fifth frame (120/5 = 24). The video players in all web browsers are very low performance and drop frames effectively randomly, especially full screen. This can make otherwise excellent motion look poor. Quote Link to comment Share on other sites More sharing options...
Guest Ebrahim Saadawi Posted October 10, 2014 Share Posted October 10, 2014 Again: same as matt's question, why can I set the shutter speed to 1/25s on the C300 when shooting at 24p if it's recording 60 frames each second? Lowest possible shutter speed can't exceed 1/60s. Quote Link to comment Share on other sites More sharing options...
Administrators Andrew Reid Posted October 10, 2014 Administrators Share Posted October 10, 2014 Same way you can go to 1/8 or something like it at 24p on an A7S. It just puts the same exposure on multiple frames. Quote Link to comment Share on other sites More sharing options...
Guest Ebrahim Saadawi Posted October 10, 2014 Share Posted October 10, 2014 Some sort of frame blending? It would be highly unacceptabble from Canon if the camera doesn't expose each frame for 1/25s when I set it to 1/25s shutter speed, especially if it's not clearly stated. When I set the shutter to 1/25 I want the frame motion to be captured exactly as in a 1/25 still photograph, exposed for the same amount of time and giving the exact same exposure. -by the way the lowest shutter on the C300 possible in 24p is 1/24s, and in 25p 1/25, and it 30p it's 1/30s, 50p is 1/50, 60p is 1/60s. This is in the standard shutter speed mode. There's a "slow" mode that separate and let you record 1/8s 1/12 with some sort of frame blending. Quote Link to comment Share on other sites More sharing options...
andy lee Posted October 11, 2014 Share Posted October 11, 2014 well this is a can of worms - I had no idea Canon did 24p this way Im sticking with Panasonic !! (we will probabally find out soon they do it as well!!) Quote Link to comment Share on other sites More sharing options...
capa150 Posted September 9, 2021 Share Posted September 9, 2021 I just found this pdf: It states something different: "when the new image sensor is set for a 24-frame picture capture rate the readout of the optoelectronic transformation takes place at a higher speed of 1/60 second. That significantly reduces the “rolling shutter” effect that is synonymous with CMOS image sensors." Note it says 1/60th shutter speed, not 60fps. via http://www.theodoropoulos.info/attachments/076_EOS_C300_New_35mm_CMOS_Sensor_WP.pdf Quote Link to comment Share on other sites More sharing options...
barefoot_dp Posted September 9, 2021 Share Posted September 9, 2021 On 10/11/2014 at 10:46 AM, Andrew Reid said: Same way you can go to 1/8 or something like it at 24p on an A7S. It just puts the same exposure on multiple frames. The way the A7s or other cameras do this is by lowering the frame rate... So how is this possible if you're also claiming the Canon can only read the sensor at 60fps? Quote Link to comment Share on other sites More sharing options...
fuzzynormal Posted September 10, 2021 Share Posted September 10, 2021 2014, eh? So what's happening with Bill Cosby? We ever find that Malaysian airliner? Xavier Plagaro Mussard, Emanuel, Tim Sewell and 3 others 2 4 Quote Link to comment Share on other sites More sharing options...
barefoot_dp Posted September 12, 2021 Share Posted September 12, 2021 Haha I didn't even notice that. Just saw it at the top of the feed and replied! I guess in 2014 they might have still been figuring the EOS Cinema thing out. Quote Link to comment Share on other sites More sharing options...
capa150 Posted September 12, 2021 Share Posted September 12, 2021 Yeah it's an older post, but it checks out. 😉 I'm looking at upgrading to a C300 from my Nikon D3300 ... doing research and came across this post. C300's are going for just over a grand on eBay now ... down from $16,000 msrp! The Komodo might be my dream camera but it's $6k and I don't think I can justify that expense. I'm totally into 24P so any weirdness on that is something I'd like to avoid. Fortunately it looks like 24P is pretty normal on the C300. Or normal enough. Quote Link to comment Share on other sites More sharing options...
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