Thread: Helium Sensor Smearing

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  1. #1 Helium Sensor Smearing 
    Is anyone else having sensor smearing issues with the Helium? I know it was a problem with the Dragon, but I've now been noticing weirdness with my Weapon Helium where there is a green band across the screen whenever there is something bright white, that goes to very dark/black color. Sometimes not even in direct light.
    Weapon, Dragon, A7SII
    Zeiss Otus 28, 55, 85
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    davidjbuchanan.com
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  3. #3  
    Quote Originally Posted by Vladimir Cazacu View Post
    Thanks, but I read this a while ago and I'm not getting that exact effect. It looks more like the sensor smearing that was on Dragon, but more controlled.

    Unless mine is an extremely less case what that guy was having. Never did say if he got the problem fixed.
    Weapon, Dragon, A7SII
    Zeiss Otus 28, 55, 85
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    davidjbuchanan.com
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  4. #4  
    Having owned my Epic-W for a year, I've only seen smearing once. It happened when I was testing extremely low light stuff at a dinner party at my house. We had some small table-top torches set up for each table so this was a pretty large flame. 1600 ISO v2 (3200 v1), STH OLPF, firmware version 6.4.21.

    The two sources you see in frame are the only ones lighting the shot. I found it interesting that the flame showed the smear but the lightbulb in the back which is also clipped doesn't. Perhaps it's a contrast thing, the lightbulb doesn't show it because there's still something to expose for immediately next to it. The flame only has pitch black behind it so it shows the streaking? I dunno.

    In my case, it was more blue than green.



    None of the other footage that I have with clipped highlights show the same thing. Maybe tomorrow I'll test and see if I can replicate it.
    a.k.a. Lochness Digital
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  5. #5  
    Senior Member Marcus Friedlander's Avatar
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    Do you think it may have something to do with the type of source, rather than just the exposure levels? They may be both clipped, but the lightbulb is a single filament encased in a bulb, so it reads as one consistent and continuous source of illumination. But since fire flickers, and puts out light inconsistently, maybe that is having an adverse effect on the hardware or software side of the imaging pipeline?

    And this may be out of left field but I thought it was an interesting thought. Since the blue artifact you are talking about is on the edge of the fire, could you be seeing the result of heat exposing the sensor, and not light? Kind of like how you get blue fire instead of red fire if the fire doesn't have enough oxygen? But applied to digital imaging.
    Cheers,

    Marcus Ian Friedlander





    RED EPIC DRAGON #03179 "Squillium the Dragon"


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  6. #6  
    Oh, no, that blue on the right is fringing from being wide open on a Contax 35mm f/1.4.

    Here's it boosted to ISO 5000 so it should be really apparent where the streaking is happening now.



    It's almost like extreme clipping is changing the color of the noise floor.
    a.k.a. Lochness Digital
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  7. #7  
    After some testing today I can invoke some smearing with my flashlight when shooting at 3200 ISO and low contrast IPP2. 800 with medium contrast I can barely even make out the smear, and that's with me actively looking for it. It seems very well controlled on my camera.

    David, what ISOs are you shooting at where you're seeing this problem?
    a.k.a. Lochness Digital
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  8. #8  
    Quote Originally Posted by Aaron Lochert View Post
    Having owned my Epic-W for a year, I've only seen smearing once. It happened when I was testing extremely low light stuff at a dinner party at my house. We had some small table-top torches set up for each table so this was a pretty large flame. 1600 ISO v2 (3200 v1), STH OLPF, firmware version 6.4.21.

    The two sources you see in frame are the only ones lighting the shot. I found it interesting that the flame showed the smear but the lightbulb in the back which is also clipped doesn't. Perhaps it's a contrast thing, the lightbulb doesn't show it because there's still something to expose for immediately next to it. The flame only has pitch black behind it so it shows the streaking? I dunno.

    In my case, it was more blue than green.



    None of the other footage that I have with clipped highlights show the same thing. Maybe tomorrow I'll test and see if I can replicate it.
    Yes! That's exactly it! And it looks like shit! How come everyone says they've seen it once, or twice, but as I look through my past clips I'm seeing it more often? Really, the thing that bugs me, besides spending $50K on the camera, is that there's no inclination to fix it. It was on the Dragon, now it's on the Helium.
    Weapon, Dragon, A7SII
    Zeiss Otus 28, 55, 85
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    davidjbuchanan.com
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  9. #9  
    Quote Originally Posted by David J. Buchanan View Post
    no inclination to fix it. It was on the Dragon, now it's on the Helium.
    Perhaps you don't remember, but performance significantly improved from Epic Dragon to Weapon.

    http://www.reduser.net/forum/showthr...=1#post1560005

    Quote Originally Posted by Phil Holland View Post
    Whelp, here's the other thing that I can officially classify as useful information. Specifically in regards to comparing RED Epic Dragon to RED Weapon.

    I spent the first half of my day at Camtec with Christopher Probst going over our Weapon notes and shooting a few tests. We had 3 Weapons and 2 Epic Dragons on hand.

    My focus today was on a specific stress test. CMOS Smearing. Like I said earlier RED Weapon has an improved optical path and some other voodoo that has changed things for the better on this front in a few ways. Here's a sample image:



    A few things to take note of here:
    - This is a stress test and I'm doing my best to make an ugly image, the key light in frame is +6 Stops over exposed.
    - This example is of the Skin Tone - Highlight OLPF, which does indeed exhibit CMOS Smear easier than the other OLPFs due to it's profile/calibration.
    - To show the "extremes" this is ISO 4000, DRAGONcolor2/REDgamma4.
    - CMOS Smear is indeed significantly improved on RED Weapon compared to RED Epic Dragon.
    - IR Blocking and/or Cutting has also been improved.
    a.k.a. Lochness Digital
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  10. #10  
    Quote Originally Posted by Aaron Lochert View Post
    Perhaps you don't remember, but performance significantly improved from Epic Dragon to Weapon.

    http://www.reduser.net/forum/showthr...=1#post1560005
    Welp, the sensor smearing I've encountered doesn't look like that. That barely looks like it's there. Not to mention yours looks horrible, but if you've only seen it once then you're in good graces.

    Yes, it is better than the Dragon, but not good enough. It's pretty obvious on the footage that I've been pulling up and now I'm crushing certain parts of my images to get rid of it. It's an annoyance that I don't think should be there in the first place.
    Weapon, Dragon, A7SII
    Zeiss Otus 28, 55, 85
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