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  1. #11
    polyglot's Avatar
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    Obviously, your shutter speed has to be slow enough to encompass a full scan of the screen, which is about 90% of the refresh period; otherwise, you will see only a narrow stripe of image on the screen.

    More sync issues: monitors normally run with a refresh rate that is much higher than the frame rate of the video they're displaying. 60, 72, 75, 80, 85Hz (PC monitors), 100 and 120Hz (frame-doubling LCD TVs) are all fairly-widely used refresh values. This may well cause you problems if the monitor's refresh rate is not an integer multiple of the frame-rate of the video that is being shown on the monitor and it will definitely cause problems if the monitor's refresh rate is not synchronized with your shutter.

    For example, 25Hz (50 fields/sec interlaced, PAL) video on an 80Hz PC monitor will mean that most frames are displayed for 3 refreshes but some frames will be displayed for 4 refreshes, which causes a slight staggering effect that's not visible to a human. If you shoot it at 80fps and then throw away a bunch of frames to get back to 25fps, it will work, but I'm guessing you can't do that... If you shoot it at 25Hz, the monitor's refresh will not be synchronized with your shutter, which means you will get black bars walking up/down the screen.

    If using a CRT, you must ensure your shutter is synchronized to the vertical refresh of the monitor. It's not enough to have them at the same rate, they must occur at the same time or you get black bars through your image. Wrong rate and the bar moves; right rate but unsynchronized and the bar just sits there in your image.

    With LCDs, it's a little easier because the image doesn't scan, but it is refreshed using a scanning process. If you shoot an LCD with an unsynchronized shutter, you will get horizontal tearing artefacts where you capture part of one frame and part of another. That looks bad because the frames are obviously different, and you can see the discontinuity at a tear-line across the screen. This line will move around in the same manner as the black bar on a CRT depending on your synchronization or lack thereof.

    If you're shooting a device with a VGA or DVI interface, you can pull the vertical sync signal from the cable using a bit of electronics and if your shutter is flexible enough, synchronize it to the vertical sync pulses. That will require a bit of electronics to process the sync signal and some sort of interface to the shutter.

    Can your 16mm camera shoot single frames? If so, it might be much easier to set it to a longer shutter speed that encompasses a few refresh cycles of an LCD and then capture the video one frame at a time to your film. That way, you avoid problems synchronizing your shutter with the monitor refresh and you also avoid telecine and pull-down problems with the video frame-rate as long as you have a video source of the same frame rate that you want your film to be at.

    One more thing: "full HD" resolution is only 1920x1080 or about 2MP, which is a small fraction of what you can get on 16mm. If your 16mm camera is focused on the screen, you'll be able to see pixels. Might want to defocus it just enough to blur the pixel edges out, or at least make sure the screen-door effect (black lines between the pixels) is not recorded on film.

    I would definitely recommend neg film instead of reversal because I think you'll need to use some adjustments in printing to control your black and white points. 80's CRTs had very very poor contrast; modern monitors are better but in some cases, their "black" isn't very black.

  2. #12
    polyglot's Avatar
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    Oh yeah, I think there are hybrid print-to-film services. You give them a video file and a spool of film and get exposed film back. Might not be cheap, might not fit with your aesthetic, but there are people who will digitally print images directly to film for you.

  3. #13
    nick mulder's Avatar
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    Quote Originally Posted by polyglot View Post
    Obviously....

    I would definitely recommend neg film instead of reversal because I think you'll need to use some adjustments in printing to control your black and white points. 80's CRTs had very very poor contrast; modern monitors are better but in some cases, their "black" isn't very black.
    Thanks - but I'm afraid this is just going to get off topic...

    Have you read what I've written ???

    In reply:

    Super16 with a modern 50ASA stock levels out at about 2K res - any more and you're just making the grain look more 'correct'... I know this from both experience and other professionals advice online (if that holds any weight, who knows)

    I've tried (read what I written already) - but I dont know how to say this more clearly:

    I DONT NEED ADVICE RE. TIMING/SYNC ISSUES

    I've done this before, I've succeeded in it - I know about it...

    What I did was high con (titles) and could be individually maximized at the scanning step - this time I'm pretending out of interest that I can only get a 'one light' scan/telecine and that the LUMINANCE needs proper care in a more continuos scene...

    IMAGINE I WANT TO TAKE ONE PHOTO OFF A SCREEN - AS THIS IS IN ESSENCE ALL I'M DOING (JUST A LOT OF THEM)...

    Put simply:

    What are the effects of the required push to bring a scene (** forget it's a screen **) with a DR of 6 to optimize the latitude of film *on* the distribution of shadows and highlights along the curve ?



    excuse the caps, bold and italics - I'm frustrated, long day ...




    Cleared the bowel problem, working on the consonants...

  4. #14
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    filming cine

    This has absolutely nothing to do with your question, but it reminded me of the story of the very first public demonstration of TV. The press showed up with their photographers and 4x5 speed Graphics And one by one they lined up in front of the set and shot a picture using flash bulbs! The engineers demonstrating were flabbergasted and never said a word Never heard what happened when they all got back to their papers and developed their film!

  5. #15
    nick mulder's Avatar
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    heh heh - nice story

    I've found I've got a bit further with the same question at hybridphoto with one user and cinematography.com with a cine tab tech - interesting stuff !

    I'm sidetracked with other work at the mo' tho and cant get down to it quite yet ...
    Cleared the bowel problem, working on the consonants...

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