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    "Sensor Flares" - what's the truth?
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    Recently there's been a lot of buzz and discussion over the concept of "sensor flares" and, particularly, the AF100. A blog article claims that there's a big problem with the AF100 that causes unacceptable flares, and that article has been tweeted and retweeted over and over, and it's stirring up a lot of fear, uncertainty, and doubt. Links to the original article were posted here on DVXUser, but the OP's behavior in the thread led to the thread being deleted (the reasons for which, the OP kindly made public by screenshotting the report). It wasn't the subject matter that was a concern, it was the tone and the FUD that was the problem. Here's some of the phraseology that caused concern... the original blogger used terms including:
    "obvious Panasonic design flaw"
    "a source of HUGE disappointment and a deal breaker"
    "This issue is very severe and will ruin a lot of otherwise beautiful shots"
    "Panasonic, go back to the drawing board!"
    "AF100 camera is a prototype!"
    "released without thorough testing"
    "It hurts that we can't use it with any lenses!"
    "it is a DESIGN FLAW of the camera."

    Wow. Strong words. You'd think the AF100 was out there destroying shots and kicking puppies. How simply horrible it must be, right?

    Well, let's find out. I looked into the issue. My method of testing was to use an LED light, because when the flare shows up, it reflects the individual LED's and makes it very easy to see. Now, first of all, in order to test for this, you have to shine a very bright light directly into the lens -- the wisdom of which is suspect, but hey, I'm game, let's try it...


    Well, there it is, in all its glory. Clear as day, reflected flare. So, should we execute the AF100 right now and be done with it? Seems like our friend the blogger thinks we should (after all, he says it's a prototype and needs to go back to the drawing board). But I wonder... is this an issue that's strictly limited to the AF100?

    I looked around to see what other interchangeable-lens cameras I have. Hmm, there's the GH2, let's try that. Blare the light directly into it, and ...


    ACK! There it is again! Oh no ... maybe all Panasonics are haunted! How terrible this day is, to find out this horrible truth, isn't it?

    What else do I have that has interchangeable lenses? Well, look, there's my Super16 film camera, let's try that. Obviously that won't have the issue, because it's not made by Panasonic... okay, let's shine the light in and ...

    Well, what do you know. There it is. The exact same lens flare. The same "sensor flare" is happening on a 16mm film camera. (No video to show it, because the viewfinder opening on the camera is about 1/4" in diameter and I couldn't figure out how to film the ground glass through that opening). But I assure you it's there and looks very similar to the AF100/GH2.

    Clearly, this is a DESIGN FLAW of all movie cameras, right? Perhaps my 1970's-era movie camera is a prototype and needs to be sent back to the drawing board?

    Fortunately for us, there are other brands we can turn to. For example, the Sony F3. That's a digital cinema camera, brand new, and costs 3x as much as the AF100. With such a higher pricetag (and none of those "incompetent" Panasonic engineers working on it) it'll be free from such an issue, right?

    Right?

    Oops. Have a look at Hello World Communications' gorgeous candlelight test of the F3.

    Beautiful, rich, lush cinematography but WHAT -- wait -- at 00:45 to 00:52, what's that on the left? Yep, there it is -- the dreaded green ghosts! And Timur Civan, an F3 owner, has confirmed for me that he's had it happen on his F3 too.

    Well, heavens to betsy and with much wringing hands, whatever are we to do? It must be a conspiracy by all those big Japanese companies, trying to stick us with inferior designs and "obvious flaws". I guess we have no choice but to turn to Red to free us from the dreaded "sensor flare"... so let's go look at some Red Epic footage...

    Stephan Gray posted that Red Epic low-light footage, shot at 2000 ISO, and ... uh-oh. What's that at 00:32-00:35? It can't be! But it is -- it's the dreaded "sensor flare!"

    Oh no! Recalls and lawsuits, whatever are we to do? Well, at least there's one place we can turn to. The blogger said that the flares were practically nonexistent and much-better-controlled on his 7D, so we can always just go back to using a DSLR, right?

    Er, not so fast. Hold your horses and hang onto your lunch. Philip Johnston of HD Warrior posted a (much-shorter) rebuttal to the original blogger's article, and showed just how much of a sensor flare his Canon 5D Mark II has:


    Interestingly Philip said that before he got this ghost shot on the 5D, he also shot the same thing with a bunch of other cameras, including a Sony MC50, Canon G12, Panasonic G2 and Sony HX5V. All of them delivered the same "Green Ghost" issue.

    So -- where do we stand? Here's where we stand -- it happens. It is not an "AF100 problem" or a "DESIGN FLAW" or anything of the sort. It's an artifact that happens when you point a very bright overexposed light directly into the lens. Of course, this is old hat to any shooter who's been around a while; we all know that you're not supposed to purposely point a bright light directly into the lens or you'll get flares (including flares off the back element). For those who are panicking about it, it makes me wonder if they've never shot on a CCD camera? In the older days, there was another (far worse) reason to avoid a bright light directly in your shot, and that's the vertical smear that a CCD would exhibit:


    (hotlinked from www.wikipedia.org's article on CCD cameras).

    That artifact was far more glaring and noticeable and inescapable than a ghosted reflection, but it taught us not to point the camera into extremely bright light sources (and not to point extremely bright light sources into the lens!) With CMOS, the vertical smear doesn't happen anymore, so now maybe people are more inclined to point directly at a bright light source? I don't know, but it's just common cameraman technique to not do that, or -- if you do decide to do that, you accept the consequences: lens flares.

    Look -- here's the bottom line -- if you want to go out of your way to find a flaw in a camera, you can do that. Every camera, every lens, every recording format has limitations. Is it good to know those limitations? Sure -- that way you won't run into the problem. But EVERY camera has its limitations.

    Is it helpful to find a limitation and call it a "DESIGN FLAW" and a "dealbreaker" and then re-tweet it to everyone on earth trying to stir up pandemonium and scare people from using a valid product? Of course not. To do so is the very definition of FUD -- it's spreading Fear, Uncertainty, and Doubt. We're not big fans of FUD here. We are focused on exploring what these cameras do and then teaching people what to do, and what not to do, to get the best results (and here's the lesson for today, folks -- don't go blaring a bright light directly into your lens!)

    So let's turn to practical considerations -- can you actually shoot with an AF100, with a bright light in the shot, without getting "sensor flares"? Of Course You Can. Here's a little example shot I threw together, it's handheld, it's not meant to be beautiful, but it's a very low light scenario (shot at f/1.4, lit with one 55w fluorescent tube) and there's an incandescent lightbulb in the background that is so hotly exposed that it's clearly clipping.

    See any horrible ghosts? Neither do I. It looks fine, just like it's supposed to. And if I was shooting this for real, I would have put a dimmer on the background light to bring it down so it wasn't clipping so ugly. And every bit that you bring that background light down, lessens the chance of it flaring and causing an issue. But even in this scenario, where it's obviously too bright and is clearly clipping hard, it still worked just fine.

    PostScript: by the way, something can be absolutely true and still be FUD -- it's all in the way it's presented. For an excellent example, I would like to point you to the following warning site about the supposedly "dangerous chemical" dihydrogen monoxide:
    http://www.dhmo.org



    That website is for the Dihydrogen Monoxide Research Organization. Read the site. See if that chemical doesn't scare you to death. Here are some of the things they say about it:
    • Some call Dihydrogen Monoxide the "Invisible Killer"
    • Others think dihydrogen monoxide should be Banned
    • Dihydrogen Monoxide is linked to gun violence
    • Dihydrogen monoxide was found at every recent school shooting
    • Athletes use DIHYDROGEN MONOXIDE, or DHMO, to enhance performance
    • Dihydrogen Monoxide has been found in our rivers, lakes, oceans and streams
    • Dihydrogen Monoxide is a major component of acid rain
    • Thousands die each year after inhaling dihydrogen monoxide
    • Dihydrogen Monoxide can be deadly
    Is any of it true? Yes, it's ALL true. 100% true. Should it be banned? Well, seeing as dihydrogen monoxide is ... well, it's two hydrogen, and one oxygen, hmm, that's H2O... yep, dihydrogen monoxide is WATER. Yes, if you inhale it you'll die. Yes it's found in our rivers, lakes, oceans and streams. Yes it's "invisible". Yes it's a major component of acid rain. Yes it's all true. But the way the dmho portrays it, it spreads fear, uncertainty, and doubt.

    Ain't gotta be a lie, to be FUD. FUD is FUD.

    Bottom line -- all these cameras work just fine, and if you blare a harsh light into them all of them will give reflected flares. So don't do that. Keep direct light from shining onto your lens (which is what flags and matteboxes are all about). And if you have to have a light shining directly into the lens, tone it down as much as you can, using ND gels and stopping the iris down -- the more overexposed the light is, the more likely it is to cause the flaring. Really, this is Camera Basics 101, but I guess with new tools comes new techniques and maybe not everyone knows these things, so it bears repeating.

    We welcome constructive discussion and when an issue is found, we welcome a constructive and productive dialogue towards how to overcome or avoid such an issue. Thanks to all those over the years who have given of their time and talent to explain things to our membership.
    Last edited by Barry_Green; 03-10-2011 at 12:46 PM.


     

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    #2
    Senior Member Jan_Crittenden's Avatar
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    Barry,

    Nice work, and nice that so many other people added to your research. In summary lens flares are the responsibility of the DP, and thus would be considered his job description to only allow the flares he wants into the frame. That isn't a design flaw, it is a job description.

    Thanks for digging into this. Hope to offer my D700 flare frame tomorrow.

    Best,

    Jan
    Jan Crittenden Livingston
    Panasonic System Communications Corporation
    Partner Sales Manager, NY and NJ


     

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    #3
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    Well said Barry!


     

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    Well done Barry
    #4
    Senior Member HDWarrior's Avatar
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    Talking
    I have to say far too much homework Barry... the chap was only seeing what we all see under normal circumstances, it's the REVENGE of the DSLR brigade and the best they could come up with was a "haunted AF100 camera" with a green ghost. PS Just before I shot my 5D pic I tried a Sony MC50, Canon G12, Panasonic G2 and Sony HX5V all suffered the same "GREEN GHOST". We should start a competition to see if anyone can produce a "BARRY GREEN GHOST" from their DSLR/Camcorder !


     

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    #5
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    I noticed the same flares in fillm footage of the Apollo launches recently :-)


     

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    Member Yves Simard's Avatar
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    Hi Barry, thanks.

    I guess the issue with information being so quickly disseminated there is nothing to distinguish it from being verified.

    Good read
    Yves Simard
    Dop/DP Producer Admin CREWS.TV

    Auckland/Australia/Asia
    +64 21 689 103


     

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    #7
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    Crushed that one like a bug! Well done, Barry!


     

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    #8
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    I'm an editor, and even I know that is not a sensor issue. It's a reflection - clearly from within the lens elements. LEDs will be especially bad because they are high-intensity and have a narrow focal point with even higher intensity. Look directly at an LED - they are very bright, a little off axis and the brightness is much reduced.

    No doubt the AF100 has real issues (what doesn't?) but this isn't one of them.
    Dylan Reeve // Edit Geek
    Editor / Post Production Supervisor / Geek


     

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    Yeah, but the girl in the F3 footage is way prettier than the mannequin in your's. And presentation matters.

    Seriously, nice work Barry!!
    Last edited by BobbyMurcerFan; 03-10-2011 at 02:18 AM.
    Jan vs Jim... I'm putting my $ on the Jersey Girl.


     

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    Junior Member HarryJoaquin's Avatar
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    Thanks Barry,

    All your research is greatly appreciated.
    Harry Joaquin Charnock
    Cinematographer / Editor
    Newborn Digital Film & Media


     

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