Author Topic: [DONE] FPS ramping (film style "flash frame" effect)  (Read 15909 times)

jeremypevar

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[DONE] FPS ramping (film style "flash frame" effect)
« on: October 02, 2012, 07:41:07 PM »
This is a bit complicated, but I'll try to explain it clearly.

In the days of motion picture film cameras there was a phenomenon known as a Flash Frame. 35mm film runs through a camera at 90 feet per minute, and it would take a second or so for the camera to get up to speed.  These cameras have rotating shutters(driven by the motor that pulls the film thru the camera), so the exposure is directly proportional to the fps.  So, for the first couple of seconds, while the motor is accelerating up to full speed, the image is over exposed.

In the 90s it became fashionable to use Flash Frames in music videos, and the aesthetic spilled over into tv and feature films as well.

I think it would be really cool if ML could simulate film Flash Frames be gradually ramping the frame rate up from 1fps to 24fps over a user defined period of time, while simultaneously over-exposing the image accordingly (ideally be adjusting the shutter speed, though ramping the ISO could also work)

Does this sound feasible?

KarateBrot

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Re: film style "flash frame" effect
« Reply #1 on: October 03, 2012, 02:07:45 AM »
sounds interesting.

(btw.: according to your explanation the exposure is INVERSELY-proportional to the fps)
If you donate a RED EPIC to me you officially are very cool ;)

jaycmiley

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Re: film style "flash frame" effect
« Reply #2 on: October 03, 2012, 03:10:48 AM »
Just do it in post production?

ItsMeLenny

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Re: film style "flash frame" effect
« Reply #3 on: October 03, 2012, 08:26:28 AM »
Definitely do it in post. Magic Lantern is more about unlocking canons limits, not special fx.

jeremypevar

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Re: film style "flash frame" effect
« Reply #4 on: October 03, 2012, 08:22:51 PM »
I am an editor who occasionally shoots, so I can sympathize somewhat with the impulse to "fix it in post." However, while flash frames can be imitated, they can't be truly recreated in post because of their highly dynamic nature.  Flash frames involve a ramp up in the fps from zero to the operating speed of the camera, and a corresponding ramp down in exposure, from radically over exposed to correctly exposed. The ramp in fps yields motion artifacting (apparent motion ramps from sped-up to normal) as well as a ramp in motion blurring (from an extreme amount to a "normal" amount.)

While I suppose this is sort of a "special effect" I don't view it that way. I see this as an attempt to faithfully mimic shooting on film.  I think that many DPs would agree with me.  In fact, I think HDR is much more of a "special effect" than this.

My question remains, would such a feature be feasible within the framework of ML?

nanomad

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Re: film style "flash frame" effect
« Reply #5 on: October 03, 2012, 09:04:57 PM »
I'm quite a n00b with regards to videography...do you have a video of said "flash frame"?
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glubber

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Re: film style "flash frame" effect
« Reply #6 on: October 07, 2012, 06:59:04 PM »
I played a bit with your Idea using the fps override of ML. Just hitting the record button while in FPS submenu and increasing the fps-value from 0.25to 25.
I doubt this will give You the desired "film look", but at least it's a starting point:

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jeremypevar

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Re: film style "flash frame" effect
« Reply #7 on: October 08, 2012, 06:41:50 PM »
@glubber - that is very close the the effect I'm talking about.  The only thing is that it should happen much more quickly, from one to two seconds in duration.

a1ex

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Re: film style "flash frame" effect
« Reply #8 on: October 15, 2012, 11:17:38 AM »
I think I've got it working, try in tomorrow's nightly build.

ItsMeLenny

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #9 on: October 15, 2012, 02:44:56 PM »
Well I stand corrected.

nanomad

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #10 on: October 17, 2012, 10:59:11 AM »
Tested it and works nicely, altough I'd love to see a "direction" option (slow->fast, fast->slow) because I think this effect is more suited when increasing the FPS (e.g. start from 15 and go up to 30)
EOS 1100D | EOS 650 (No, I didn't forget the D) | Ye Olde Canon EF Lenses ('87): 50 f/1.8 - 28 f/2.8 - 70-210 f/4 | EF-S 18-55 f/3.5-5.6 | Metz 36 AF-5

a1ex

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #11 on: October 17, 2012, 11:04:47 AM »
Press DISP/INFO ;)

nanomad

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #12 on: October 17, 2012, 11:15:15 AM »
Ooops, my bad  ;D
Nice job
EOS 1100D | EOS 650 (No, I didn't forget the D) | Ye Olde Canon EF Lenses ('87): 50 f/1.8 - 28 f/2.8 - 70-210 f/4 | EF-S 18-55 f/3.5-5.6 | Metz 36 AF-5

glubber

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #13 on: October 17, 2012, 01:16:07 PM »
Nice job

I second that. I did a quick tryout last night and it worked fine.
The moving orange bar at the bottom ist a nice feature too.
As far as i understand it the fps ramping starts respectivily ends at default fps (i.e. 25/30 fps),
or is it possible to go f. ex. from 1 to 15 fps?

Some promising ideas came to my mind using fps ramping over the last days, so i'm very thrilled give it a try.
EOS 550D // Sigma 18-200 // Sigma 18-70 // Canon 10-18 STM

a1ex

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #14 on: October 17, 2012, 01:27:47 PM »
For now, you can only go from user FPS to default FPS.

a1ex

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #15 on: October 20, 2012, 02:13:45 PM »
Update: now there's an option to keep the exposure constant, by compensating with ISO.

jeremypevar

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #16 on: October 22, 2012, 06:34:24 PM »
Wow! This is great! I have been away from the forum for a few weeks and am thrilled to see that this feature has been added to ML.  I am a 7d owner, and do not yet have ML installed, but can't wait to get it onto my camera to try out this feature.

Now, if only there was hacked firmware for the C300...

a1ex

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #17 on: May 22, 2014, 06:37:49 PM »
Anyone will miss this feature if I'll remove it?

It's tightly coupled with the regular FPS override code, and my impression is that nobody uses it, so removing it will declutter the FPS code quite a bit.

vertigopix

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #18 on: May 22, 2014, 06:48:39 PM »
It's easy to do in post, so... ;-)

Thomas Worth

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #19 on: May 22, 2014, 07:26:01 PM »
This is a cool idea, but there's really little advantage to doing it in camera (as opposed to in post) if you can't get the motion blur associated with mirror slowing to a stop. In a real film camera, FPS and exposure (shutter speed) are directly linked so by slowing the frame rate, you get more motion blur.

If you really want to do this right, you'll link the aperture wheel to the FPS override so we can hand crank!

glubber

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #20 on: May 23, 2014, 01:42:54 PM »
Anyone will miss this feature if I'll remove it?

Yes i will miss it!
I will use it when carnival comes to town this summer. ;)

I SHOULD have posted my results from last years carnival looong ago.
But nevermind.... i will keep an old build with FPS ramping.... I don't wanna block the enhancemenets of Magic Lantern.

EDIT: An example of using FPS-ramping: http://www.magiclantern.fm/forum/index.php?topic=12026.0
EOS 550D // Sigma 18-200 // Sigma 18-70 // Canon 10-18 STM

ItsMeLenny

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #21 on: May 23, 2014, 04:48:14 PM »
Never used it. But I do like FPS override, so if there's something that can improve FPS override then personally I'd opt for that over ramping.

feureau

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Re: [DONE] FPS ramping (film style "flash frame" effect)
« Reply #22 on: June 09, 2014, 07:26:34 AM »
Even though you can "do it in post", the slight dynamic range blowing out would look better if it were done via an actual FPS override. Please don't remove this.