Thread: Fog increases FPN on ursa mini pro?

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  1. #1 Fog increases FPN on ursa mini pro? 
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    Hello,

    I shoot a lot of scenes with haze, and with black pro-mists filters. Now I read in this topic that fog increases FPN. http://forum.blackmagicdesign.com/vi...hp?f=2&t=61221

    Does anybody has any experience with that? Or a way to counter that? Because I do not want to drop my haze or black pro mists, as it is a stylistic choice that I use to get the image that I want.

    Thanks,
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  2. #2  
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    My best advice about the pro - if you can, warm it up for 5-10minutes before shooting, and blackshade it every time you change a setup.

    It blackshades SO fast there is no reason to not blackshade every time you relight a scene or every hour to couple hours if you're really worried about FPN.

    It probably comes from one person seeing FPN with haze without blackshading one time ever.
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  3. #3  
    Senior Member Peter J. DeCrescenzo's Avatar
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    Quote Originally Posted by DanKanes View Post
    My best advice about the pro - if you can, warm it up for 5-10minutes before shooting, and blackshade it every time you change a setup. It blackshades SO fast there is no reason to not blackshade every time you relight a scene or every hour to couple hours if you're really worried about FPN. ...
    Interesting. Do you disagree with JB, or are you talking about different things?

    In the thread referenced above, JB wrote:
    https://forum.blackmagicdesign.com/v...349361#p349361

    "... the sensor calibration isn't really a black shading calibration tool. They're different. It's not necessary to run the sensor calibration tool as often as you would for other camera that require a near daily black shade. They're not really the same thing. So changing temperature or humidity won't be a trigger for running this process. The sensor calibration process is more like every few months. ..."

    ----

    In the same thread, JB writes:
    https://forum.blackmagicdesign.com/v...349263#p349263

    "... BMD's log is especially flat. You look at a low con subject in BMD film on any LCD monitor and you'll see noise and FPN that end up disappearing in a normalised grade. ..."

    -
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  4. #4  
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    Very interesting. Have any tests been done on this? I imagine you'd need some controlled environments, or one environment where you can test lots of lighting setups as well as natural light.

    I personally don't think I've seen excess FPN on my UMP, but I'm about to start grading a feature, so we'll see! I've noticed it's most strong when the scene is just plain underexposed.

    I could be crazy but it also seems like certain LUTs that pull the image (overall) way down also end up exhibiting more FPN. Some of my images look properly exposed with LUTs that don't affect the contrast as much.
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  5. #5  
    Senior Member DPStewart's Avatar
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    Shooting in fog or with heavy diffusion simply gives you subject material that 'allows' you to more easily see FPN...IF it's there.
    This of course will be the case with any camera.

    Frank Glencairn has shot TONS of stuff in fog and mist and with diffusion and his stuff always looks great. Much of it is posted here.
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    Quote Originally Posted by Peter J. DeCrescenzo View Post
    Interesting. Do you disagree with JB, or are you talking about different things?

    In the thread referenced above, JB wrote:
    https://forum.blackmagicdesign.com/v...349361#p349361

    "... the sensor calibration isn't really a black shading calibration tool. They're different. It's not necessary to run the sensor calibration tool as often as you would for other camera that require a near daily black shade. They're not really the same thing. So changing temperature or humidity won't be a trigger for running this process. The sensor calibration process is more like every few months. ..."

    ----

    In the same thread, JB writes:
    https://forum.blackmagicdesign.com/v...349263#p349263

    "... BMD's log is especially flat. You look at a low con subject in BMD film on any LCD monitor and you'll see noise and FPN that end up disappearing in a normalised grade. ..."

    -
    At the risk of sounding like a total A-hole...

    Yes, I disagree on all points listed above.

    The camera needs a blackshade any time you are even thinking you might be worried about FPN.

    I also disagree about the log mode.

    In my opinion, BMD Film on the 4.6k is more of a hybrid Log Gamma where it appears Less flat and almost usable out of camera.

    The black levels are lifted, but in appearance alone it's actually quite close to a finished image a lot of the time.
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    Senior Member Revdesign Industries's Avatar
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    Quote Originally Posted by DanKanes View Post
    ...

    Yes, I disagree on all points listed above.

    I'm telling JB on you...
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  8. #8  
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    Hahahaha hi Forrest !

    One more note - my personal Ursa Mini Pro came from the factory without being blackshade calibrated.

    Why would I think a brand new camera out of the box would be set up to work correctly?

    I was like "wow , this has a lot of FPN, hope I don't have to return it."

    On the flip side, once I calibrated it, it looks really good.

    Used This UM Pro in Prores UHD mode (film Gamma) and it cross cut perfectly with a Red Helium 8K camera using IPP2 widegammaRGB/Log3G10 in a "behind the scenes film" for a major tech company.

    Here's my birds-eye view:

    There is no greater low budget value for an independent filmmaker right now than black magic cameras.

    You get a huge feature set for the price. It has a great look.

    There are still gremlins that pop up- but that's with any camera.

    Red isn't perfect, but they've been at it long enough to squash a lot of bugs, and it has always been good for me, the image gets better every year, wide ranging feature set. small !

    Arri is still the gold standard as far as "push button - image looks good and just works" - also not perfect but also very good.

    You can make great pictures with a Canon , but their feature sets are different, sometimes limited.

    Sony makes great pictures but the interface is horrible, tons of features, often weird ones.

    Panasonic is good but doesn't have my personal attributes I seek 90% of the time
    Last edited by DanKanes; 07-14-2017 at 10:45 AM.
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    But if you blackshade on location, you also do it with the body cap on right? What difference should it make on what location you are. (or is it something about room temperature, or something).
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  10. #10  
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    Quote Originally Posted by polaroid22 View Post
    But if you blackshade on location, you also do it with the body cap on right? What difference should it make on what location you are. (or is it something about room temperature, or something).
    You should black shade with the body cap on, yes - in a pinch you can have a lens on with a fully covering black cap.

    Regarding temperature fluctuation / location - ambient temperature plays a deep role in camera and sensor temperature even in a highly managed camera like the UM / UM pro.

    If it's ambient temp of 62 degrees f and you boot the camera and want to start shooting right away, and the camera has been sitting in a bag in the car, it's going to start out cooler than ambient because it's a nice cool metal body, and will slowly climb to temperature. If you blackshaded previously after it had been in the sun on a 95 degree f day and you had been rolling for a couple hours, that blackshade will not be valid for your new situation, and it's still good to let the sensor get up to working temperature before blackshading.

    Hey! At least it blackshades nice and quick. Like really quick.

    Final summary : if you're concerned about it, take proactive steps that are available to you instead of complaining about FPN later.

    If you aren't worried - don't worry - you may never see it, and you can always bring your Gamma way down in the grade if you exposed to the right without clipping enough.
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