Frames, yes. But the projector has a double bladed shutter, so a refresh rate of 48Hz. The closer you are to the screen, the more you notice flicker. So 48Hz is just OK for a large screen.
For PAL and SECAM they usually just ran them at 25fps and lived with it. But refresh rate was 50Hz (2 fields per frame). On NTSC there was in infamous 2/3 pulldown to get to 30fps. A 60Hz refresh.
That depended on the phosphors. Long decay rates were desirable in phosphor formulations. The eternal balancing act of color vs brightness vs decay.
The video signal still contains a blanking period. It's brief, but there. DLP does a good job of "on all the time" so it doesn't matter much. LCD can do this too.
Probably best not to argue this with a video engineer/projectionist. We all have our areas of expertize.
Hi,
Well, I had to repair TV's for a while when I was blackballed by the east german government. So I know more than a little bit. And I am aware thet TV Pictures are drawn interlaced in two halves at double the frame rate (eg 25 Frames/Second for PAL/SECAM but screen refresh 50 times a second.
I also installed quite large number of commercial projectors, from the old three or four tubers to early LCD, later several home ones...
On Film projectors I'm weakest. I never much worked with these. However, the framerate remains 24Hz. And if the refresh rate is 48Hz it is basically the same as PAL/SECAM...
So my point stands however. It is NOT as such the framerate of PAL, SECAM or NTSC as such that is the problem with flicker. Even lower frame-rates than theirs are okay. The flicker is another story with other origins.
And yes, my projector (a DLP one) will do precisely 24 Frames/Second in Cinema Mode and yes, I can see the rainbow effect if I try, despite using an 8 Speed colour wheel.
Ciao T
Probably best not to argue this with a video engineer/projectionist. We all have our areas of expertize.
Well, I had to repair TV's for a while when I was blackballed by the east german government. So I know more than a little bit. And I am aware thet TV Pictures are drawn interlaced in two halves at double the frame rate (eg 25 Frames/Second for PAL/SECAM but screen refresh 50 times a second.
I also installed quite large number of commercial projectors, from the old three or four tubers to early LCD, later several home ones...
On Film projectors I'm weakest. I never much worked with these. However, the framerate remains 24Hz. And if the refresh rate is 48Hz it is basically the same as PAL/SECAM...
So my point stands however. It is NOT as such the framerate of PAL, SECAM or NTSC as such that is the problem with flicker. Even lower frame-rates than theirs are okay. The flicker is another story with other origins.
And yes, my projector (a DLP one) will do precisely 24 Frames/Second in Cinema Mode and yes, I can see the rainbow effect if I try, despite using an 8 Speed colour wheel.
Ciao T
Can't say I really understand your point. Higher refresh rates are needed for CRT and close viewing to reduce flicker. The frame rate and refresh rate used to be closely tided together for obvious technical reasons. Not so much anymore.
On the large screen 24fps with each frame shown twice is OK. Showscan at 60fps looked great, but never flew, commercially.
I use 3 chip DLP for work so no rainbow- Gave up the film projectors years ago.
On the large screen 24fps with each frame shown twice is OK. Showscan at 60fps looked great, but never flew, commercially.
I use 3 chip DLP for work so no rainbow- Gave up the film projectors years ago.
Hi,
Nice, which one? A bit too rich for my blood I'm afraid. Single chip will have to do for now. Still, next to a LCD projector...
Ciao T
Nice, which one? A bit too rich for my blood I'm afraid. Single chip will have to do for now. Still, next to a LCD projector...
Ciao T
Speaking of Objective vs Subjective and hearing things.
Today I drove my wife's car. The radio was on the local "Oldies" station, but turned down low. A song came on that I recognized - Blinded by the Light - Springsteen. But why were they playing a cover of it? Seemed strange that an oldies station would play a cover of that song. Turned up the radio and it was unmistakably Springsteen.
Just that low level was enough for me to mistake it for another version. That surprised me.
Today I drove my wife's car. The radio was on the local "Oldies" station, but turned down low. A song came on that I recognized - Blinded by the Light - Springsteen. But why were they playing a cover of it? Seemed strange that an oldies station would play a cover of that song. Turned up the radio and it was unmistakably Springsteen.
Just that low level was enough for me to mistake it for another version. That surprised me.
In the early days of TV they developed interlacing to increase the refresh rate because at anything slower than 50Hz it flickered terribly. (They weren't relying on phosphor persistence, but persistence of vision in the eye). This system was extremely clever because it gave the best of all worlds: faster motion capture, reduced flicker and higher resolution for the same bandwidth.
In recent years, with the availability of digital technology, in TV production other than news and sport, there has been a move away from this high frame rate interlaced video ('50i' or '60i') to '25p' or '30p' progressive mainly because 'it looks like film'. 25 frames per second isn't quite fast enough to capture reality and its film-like appearance is instant shorthand for 'sophistication' or 'glamour'.
In my opinion it is used far too much, particularly in supposedly gritty drama, comedy and music where the old high frame rate stuff felt much more intense and intimate. Very recently I think there may have been a bit of a move back to higher frame rates where appropriate - on British TV at least - but there are still soap operas set in hospitals etc. which look completely wrong in 25p.
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Hi,
I guess we need to double blind test this. Can Manfred Man reasonably be mistaken for bruce springsteen , if played loud enough...?
Ciao T
I guess we need to double blind test this. Can Manfred Man reasonably be mistaken for bruce springsteen , if played loud enough...?
Ciao T
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Hi Michael, funny how somethings are:
Apparently Springsteen was mad as a wolverine when he gave the rights to cover it and then heard the result. I would be too. Manfred Mann took a great piece of work and ran it through a pop music blender with the lid off. Personally I like to turn his version off as it does more harm than good to my ears. Greetings from Asbury Park is still one of my favourite albums. So earthy and real. Not like his later pop (let's make some money) stuff.
To each his own I suppose.
Apparently Springsteen was mad as a wolverine when he gave the rights to cover it and then heard the result. I would be too. Manfred Mann took a great piece of work and ran it through a pop music blender with the lid off. Personally I like to turn his version off as it does more harm than good to my ears. Greetings from Asbury Park is still one of my favourite albums. So earthy and real. Not like his later pop (let's make some money) stuff.
To each his own I suppose.
Was going into the S.P.D. thread but its closed
New research shows that we control our forgetfulness
New research shows that we control our forgetfulness
Geez guys I simply stated that old 50Hz CRT TV's bothered me, and yes I see the 48Hz gate on film but the surface brightness issues are totally different. FWIW I prefer 24FPS for film and find high FPS video production a little harsh and in your face rather than more intimate.
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