[Konvas] frame rate questions: put on your thinking caps and break out your calculators

[colcam at aim.com]

 Backing up a bit--? you shoot at 24fps, you project at 24fps, but you see the movie at 48 images per second.

There is an "interrupter blade" that rotates through the image while dwells in the gate and that image stays on screen, so "project @ 24 is see at 48" is reality. 

The early research came to the conclusion that "optimum" viewing was at 48 frames and images shown per second, but that well over 99% of the people watching could not tell a difference between the optimum 48 and the "sight lag" showing at 27 or 28 frames per second, and the use of the interrupter blade meant you could shoot at 16fps (the old silent rate) and show something at 16 frames per second AND see it at 32 images per second-- with less than one in five thousand seeing the flicker strobe.

The original tested rate for "sound lock" was 20 frames per second with an external audio system because, even without the issue of flicker strobing, lips and sound didn't remain matched properly, with one jumping early-late for sound and lips at 16fps.? The 24fps was "sound married" standard, where the sound was on the film and married to the image. 

The old 24/25 issue has become mostly 24fps shooting or 30fps shooting simply because it is a world market standard, and the European Broadcast Standards committee, which is so secret it makes spy work look absurd, has been pushing for a new worldwide capture standard of HD at 30p.? As strange as it sounds, the newer HD sets can automatically detect and reset the view rate to match the delivered rate, so a "common capture standard" saves the broadcasters money on exporting--? and they want to crack the North American Market, so they are pushing for the worldwide capture standard.

And 60i is "30 frames per second" because each field is one half of the image, so you only get a complete image 30 times a second.

If you notice fine print you will already notice that the "Region Free" copy of a DVD plays on any DVD player hooked up to any set anywhere in the world.?? The "image files" on the DVD are not the rate the TV you want to use is set at, but instead a copy of the capture rate, so the DVD plays at 24fps and the player converts it to the TV signal, or the DVD plays at 25fps, or at 30fps, but the image output standard selected controls what the TV set shows you.

And, BTW, the black stripe on the mirror in the camera helps get rid of operator headaches, too.






-----Original Message-----
From: Adam Frey <thefirstrule at chainsawlinux.com>
To: Konvas Discussion List <cinema at konvas.org>
Sent: Thu, Sep 24, 2009 11:53 pm
Subject: Re: [Konvas] frame rate questions: put on your thinking caps and break out your calculators









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dweber101 at comcast.net wrote:?

> Exposure time and FPS don't really have such a direct effect on 
> perceived quality, strobing excepted.  It's more the amount of 
> magnification, quality of camera lens and projector lens that affects 
> quality. 16 is limited by the amount of light that can be crammed thru 
> the projector aperture but when blown up to 35 can look very good on a 
> big screen.?
?

Agreed, lens quality, registration, etc are all extremely important. But 
strobing is one of the issues that I'm talking about. At 24 frames per 
second, there is a wider (unlit) gap between frames. You may not think 
you notice it, but it is still there and your brain is subconsciously 
registering it as unlit (or dark).?
?

I honestly don't think most viewers can notice a difference between 
Super16 and 35mm (well, maybe a little bit of a difference, but most 
would shrug it off and completely forget about it). Of course, the sad 
truth is that half of those would probably not notice the difference 
between Super8, HD, and 35mm for that matter...?
?

But I'm looking for concrete numbers, if possible. Since concrete 
numbers can settle arguments a little easier.?
?

Come to think of it, if the film were to be transferred to 1080i60 HD, 
then it isn't strobing, so much as the 3:2 pulldown is showing redundant 
frames and also interleaving B/C and C/D, which creates a new set of 
issues with perceived image quality. At that point, I doubt it hurts 
fairly still images, but I don't think it helps moving images on the screen.?
?

And, speaking of which, has anyone transferred 24fps (or 24p) derived 
footage to either 1080p60 or 720p60? How does the pulldown pattern work? 
I'd assume it's a weird pulldown variant from the 3:2 interlaced 
pulldown, but using progressive frames. Probably something like 
AAABBCCCDD. And if it is transferred that way, how would this effect the 
perceived image quality...?
?

Hmmmm. Maybe I just need to quit thinking and go to bed...?
?


Good night, everyone!?
?

Adam Frey?

Director/Cinematographer?

Crimson Chain Productions?

http://crimsonchainproductions.com?

Cell: 301-639-7146?
?

Crimson Chain Productions?

PO Box 35?

Libertytown, MD 21762?
?

_______________________________________________? 



 

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