Uwe Lansing
Veteran
What if you wanna work with the *wrong* shutter speed
Then you´ll get 50hz flickering either way , whether you shoot with 24fps, 25fps or whatever... ;-)
Who would not buy a GH2, if there are no 25p?
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Then you´ll get 50hz flickering either way , whether you shoot with 24fps, 25fps or whatever... ;-)
Olly Knights
Member
Ha ok I'm dickin' around but the major issue is syncing with 25p projects, no 25p x time/money = No GH2
Rolf Silber
Veteran
Okay - in classical film you could avoid flickering at 24 fps when you would set the shutter to 172 degrees instead of 180. But, sorry, this only applies to a mechanical shutter as far as I know.
This can't be done with a video camera. Actually I wonder how you come to the conclusion that a change of shutter speed (NOT opening of rotating shutter), will lead to flickering when you run a camera in 25 p in 50 Hz land? Okay, here is my take and I am happy if you prove me wrong:
You are all the time in sync if you run 25 p or an increment of it in 50 Hz land, okay? In theory at a certain point you will have such a short shutter time, that you may fall perfectly between two impulses of such a lamp. But I doubt anybody will shoot with a shutter 400 or 1000 under articifial light.
The point is that you are indeed out of sync with the grid if you shoot anything that is not 50 or 25 p but stay in sync if you only step up in an increment framerate- not exposure time. If I have, say, four impulses per 25 p frame, I have two for 50p, one for 100p. But you are all the time in sync, if you shoot a different exposure time. If you have a 60 exposure time and run on 25 p in 50 Hz land, you have instead of, say, four impulses per frame three and a half .... but you have them constantly because you are still 25 p and run in tact with the grid but not when you shoot 24 or 30 or 60 fps.
You only do not normally see it if you shoot 24 p in 50 Hz grid-land because you either work under tungsten light or you have in most cases light sources that have their frequencies so high powered so they give enough impulses per second that this problem is avoided. But you are definitely out of sync with the grid. And this is the problem of 24 p to 25 p.
Now - I would be happy if I am wrong. I am distinctively "old school" coming from classical film and maybe don't see the problem and I am happy to learn. And please tell me why and how I avoid all the other sync, sound-pitch and pull down menu problems with 24 p in a 25 p country.
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Uwe Lansing
Veteran
Just experience... I shot a lot of material with different video dslr´s. As long as you shoot with a shutter speed of 1/50 or 1/100 you´ll get no 50 hz flickering - be it at 24fps, 25fps, 30fps, 50fps or 60fps. If you shoot with 25fps or 50fps.. lets say with a shutter speed of 1/60 or 1/120... definitely flickering in pal lands will show up. That´s all I can say. If you don´t believe it - just give it a go...
Matthew P
Well-known member
I always thought it worked how tipota said. Perhaps the flickering occurs in DSLRs because of the rolling shutter? When I've shot 50i on a camcorder, it always works fine whenever the shutter is 120.
I'd be interested in hearing the theory behind why the shutter speed effects it, though.
I'd be interested in hearing the theory behind why the shutter speed effects it, though.
What if you wanna work with the *wrong* shutter speed
Then 25p will still give you the same issue. Shutter speed will correct the issue though.
The point is that unless you are producing PAL Blu-rays then you don't need 1080p 25p. That is the only transmission method for Pro quality 1080p @ 25 FPS video currently. If you are streaming it then use 24p and it will display perfectly on any computer or monitor. If you are shooting for DVD then 1080i will produce excellent 576p @ 25 FPS video.
Uwe Lansing
Veteran
Even then there is no need for 25fps because 25p isn´t part of the bluray specs, but 50i is: http://en.wikipedia.org/wiki/Blu-ray_Disc
Olly Knights
Member
Sure but your talking presentation, what about those of us who simply need 25p to fit into a 25p workflow, due to using other gear rated at 25p and using sync sound for instance? Or working with other PAL shooters and editors who are used to and fully expect 25p material from you? It means a lot of messing around that costs time and money. It's not as simple an issue as you are making out, as I said it's all relative!
Regards
Simon Höfer
Veteran
Don't you people get, that 1080 25p is the most flexible and most versatile format? You don't have to worry about flickering and you don't have to decide before shooting for which output this project is intended. We want 25p and we want it at the highest possible bitrate.
Uwe Lansing
Veteran
No doubt, there are quite a few reasons one can imagine to implement 25p. I´m not an opponent of 25p as I´ve already posted here: http://www.dvxuser.com/V6/showthrea...ssion-thread&p=2114888&viewfull=1#post2114888 But I have still doubts that the implementation has to be a "must"...
Ian-T
Veteran
I don’t believe flickering has anything to do with frame rates. It has to do with shutter speeds. I think folks mess up the two because traditionally PAL cameras had 1/50 and 1/100 shutter speeds where NTSC had 1/60 and 1/120. Shoot 1/60 or 1/120 in PAL land then you’ll get the flickering. If the GH2 can shoot 1/50 and 1/100 shutter (even without 25p) then I don’t think there will be a problem with the flickering.
Wow, I didn't realize that. I knew they were 25FPS but I didn't realize they were all encapsulated in a 1080i container. You are right there is absolutely no need for 1080p @ 25 FPS unless you are going to do something like transfer the footage to PAL film.
It appears that Panasonic is just following the Blu-ray specifications. They have pretty much every format covered with the GH2. Don't fault Panasonic if the GH2 doesn't have a format you want. Fault Blu-ray. Or I guess you could fault Panasonic for helping to create the formats of Blu-ray in the first place.
http://en.wikipedia.org/wiki/Blu-ray_Disc
Video
High-definition video may be stored on BD-ROMs with up to 1920×1080 pixel resolution at up to 59.94 fields per second, if interlaced. Alternatively, progressive scan can go up to 1920×1080 pixel resolution at 24 frames per second, or up to 1280x720 at up to 59.94 frames per second:[91]
Resolution Frame rate1 Aspect ratio Video format restrictions 1920×1080 59.94-i 16:9 2D encodes only 1920×1080 50-i 16:9 2D encodes only 1920×1080 24-p 16:9 1920×1080 23.976-p 16:9 1440×1080 59.94-i 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only 1440×1080 50-i 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only 1440×1080 24-p 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only 1440×1080 23.976-p 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only 1280×720 59.94-p 16:9 1280×720 50-p 16:9 1280×720 24-p 16:9 1280×720 23.976-p 16:9 720×480 59.94-i 4:3/16:9 (anamorphic) 720×576 50-i 4:3/16:9 (anamorphic)
http://www.avsforum.com/avs-vb/showpost.php?p=15765039&postcount=1
Then they expect 1080i @ 25 FPS(Which the GH2 can do but the GH1 cannot) because it doesn't appear that 1080p @ 25 FPS is part of any standard specification.
Martti Ekstrand
Veteran
Yeah, do any, and I mean any kind of post treatment that involves scaling, rotating and moving the image in composites and 50i quickly makes a train wreck of my workflow as a motion graphics designer. Not to mention keying stuff, I don't do much green screen but a heck of a lot of luma keying. It's no biggie for me, I still got my hacked GH1 which provides excellent 1080 25p footage so I'll just keep on using it until AF100 - but the Lumix division sure misses one sale to me if they don't add the 25p option to the cinema mode.
Well, one guy with direct connection to Panasonic in EU and UK sure agrees about the missing 25p mode, I give the word to Philip Bloom:
Why the Blu-ray group has left out 25p from it's spec is actually a bit of a mystery as quite a bit of high end drama production for television in EU is shot at 25 fps with film cameras.
Well, one guy with direct connection to Panasonic in EU and UK sure agrees about the missing 25p mode, I give the word to Philip Bloom:
Why the Blu-ray group has left out 25p from it's spec is actually a bit of a mystery as quite a bit of high end drama production for television in EU is shot at 25 fps with film cameras.
Uwe Lansing
Veteran
In the past (pal sd times) they did a so-called "pal speed up" to get a 25p dvd: http://www.michaeldvd.com.au/articles/PALSpeedUp/PALSpeedUp.asp AFAIK that isn´t necessary anymore with the newest bluray dvd´s because every modern bluray-player and hdtv is able to display the native 24p movies - be it in europe, australia... or wherever. So 1080p24 has been accepted as bluray standard in europe too and therefore they use the proper speed.
Regarding the flickering problem 2 interesting clips at vimeo:
http://www.vimeo.com/4991966
http://www.vimeo.com/4972364