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Carl Craver

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Posts posted by Carl Craver

  1. Hi, I've written an iPhone app that can measure light frequency directly called FlickerFinder. Essentially you point the phone towards the light, it will autoexpose to reveal and measure the flicker, then give you a suggested shutter speed. It's in the final stages, I just need some help calibrating the rest of the iPhones. https://flickerfinder.com

    Alternatively if you know the frequency you can use a typical flicker free calculator app: https://apps.apple.com/app/id1514983816

    Hope this helps.

    6999hz7.jpg

    flickercalc2.png

  2. Hi, I've written an iPhone app that can measure light frequency directly called FlickerFinder. Essentially you point the phone towards the light, it will autoexpose to reveal and measure the flicker, then give you a suggested shutter speed. It's in the final stages, I just need some help calibrating the rest of the iPhones. https://flickerfinder.com

    Alternatively if you know the frequency you can use a calculator app https://apps.apple.com/app/id1514983816

    I hope it helps, I can answer any questions.

    6999hz7.jpg

    flickercalc2.png

  3. Hi everyone,

    I'm looking for testers for a new FlickerFinder App which helps crews spot flicker on set.
    https://flickerfinder.com

    Anyone who signs up for early access will get an extra free copy at launch to share.

    An in-camera test to find flicker isn't ideal since it happens late; if there's a problem it means that the production is delayed.  Viewfinders can also mask flicker, especially at high frame rates. Sometimes props can also get mixed up and reintroduce flashlights which have bad PWM flicker. Since the problem is spread between Lighting, Camera, & Art, it's a real PITA, which is why I made the app.

    Let me know your thoughts: https://flickerfinder.com

  4. On 5/31/2019 at 12:07 PM, Phil Rhodes said:

    Hold your cellphone in camera mode really close to the light source, so it is forced to use very fast shutter timing to control exposure. The result will be a whitish screen, but if there's dark bands in it, you're likely to see a flicker problem.

    I wrote about this trick in more detail here.

    Great idea. I can imagine turning this "ad-hoc" trick into a standalone app which can visually detect flicker similar to an in-camera test. Coupled it with @aapo lettinen's waveform-view suggestion and @Robin R Probyn's FLICKERfree calculator, would it be worth a digital download on the app/android store for what, $100? I've pitched this to my programmer friend and he's started work on it on his downtime. Anyone interested to keep in touch about this?

    On 5/31/2019 at 6:43 AM, Yann Cainjo said:

    Gossen Mavospec Base can do it. UPRTEK has one too.

    https://gossen-photo.de/en/mavospec-base/

    Hi Yann, which of these do you prefer and which features do you mainly use? I'm interested in picking one up, which do you suggest?

     

    On 5/31/2019 at 10:58 PM, Robin R Probyn said:

    Shooting on Digital ,I think the only safe way is to shoot a test before hand .. 

    I've rented expensive Phantoms before, only to discover nearly every single light on set flickers when shooting at higher than 120fps, delaying the production. It's not always available for a test shot when it's actually convenient to check. But nothing can substitute an in camera test, yeah... unless you playback in real time which might sync with the problematic light 🙂 

    Thoughts about creating an app?

  5. Does anyone find light flickering tedious to fix on set? It's often checked using an in-camera test during a shoot which can slow down production. Is there any reliable & convenient way to detect light flickering given a target fps & shutter during prep instead?

    I've heard bad stories about the in-camera test failing/forgotten which caused re-shoots. Have you thought about the problem? What's your solution?

    Thanks

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