Return of Purple Fringing.

[Rick Cook]

Wow, that is really bad. I'm interested in seeing the R3D and seeing what bringing down the sharpness does.

Here is a link to one of the R3D's. Let me know what ya'll think. Worth noting this is R3D LT.

Its a wild a neon peaking effect. It's visible on edges against the sky in every backlit exterior shot Ive done regardless of stop.

https://drive.google.com/drive/folde...ht?usp=sharing

[Christopher A. Bell]

Each set of lenses that You've mentioned - has CA. Be it .CP2, FD of Canon L - all of them are known to have CA (some more, some less). They are not MP, or even UP - the more resolution you have the more of CA you'll see. While, starting from 5d mk II Canon had built-in CA corrections on the fly, I suppose something similar could be built in on some camera bodies. Thus, never seen nothing like this on Red bodies - Helium 8K, Dragon 6k, Gemini 5k, Scarlet MX - all show the same CA on my RPZ 18-85 T2.9 cine zoom.

We have had this as well in the last several generations of ENG camera bodies from Panasonic and Sony for certain higher end Fuji and Canon ENG lenses. The way it worked for my last Varicam(s), I downloaded the CAC lens files from Panasonic for the applicable lenses and loaded them into the camera and when an applicable lens was attached, it was automatically recognized and the corrections applied in real-time.

[rand thompson]

I think a better white balance helps. I don't own any FD lenses so I can't comment on how they handle C.A. throughout the Aperture range. However, as others have mentioned usually in areas where there is a high amount of contrast C.A will be exhibited. I'm not saying that the Komodo may be to some part contributing to this, I just think the Komodo may be less forgiving with slightly off white balances than usual.


Here is a different white balanced version of your clip with some C.A. control.

446MB 4096x2160 DCI
https://sendgb.com/s4JIhFXC8jv

[Mike P.]

It's not that it can't be fixed in post, the problem is if this isn't CA and actually how his sensor handles high contrast edges, it would suck a lot of ass having to fix every shot (or not being able to use ColourTemp creatively)... It's not "overheat after 12mins" bad like the R5, but it's certainly not something worth paying for.

That said, no one else is complaining about it, so I'm thinking it'd just be that Rick got a lemon (again, presuming it *isn't* CA, which is still a possibility). And as far as I'm aware, Alexa, Helium and SW/Dragon don't have realtime CA fixing, so it's not that. Could be a combo of little-to-no OLPF, higher than 3.2k resolution (smaller/<5.5u photosites), *and* the lens CA... Like a perfect storm that exacerbates the lens's artifacts (just odd that it's across all of Rick's glass).

Rick, are the other lenses as bad as that 50 1.4 FD? Cause I'd also think that if it's more or less on other glass, than it suggests it's lens performance/CA (not the sensor).

[Rick Cook]

[QUOTE=rand thompson;1917337]I think a better white balance helps. I don't own any FD lenses so I can't comment on how they handle C.A. throughout the Aperture range. However, as others have mentioned usually in areas where there is a high amount of contrast C.A will be exhibited. I'm not saying that the Komodo may be to some part contributing to this, I just think the Komodo may be less forgiving with slightly off white balances than usual.

Hey Rand, thanks for taking a look! I was able to to remove most of it via hsl and wb as well, but still can’t figure out what making this pop so much. I have tested all of my other lenses and while it’s more prominent on others it’s existing anytime a stick is against a white sky, very odd. It is very barely noticeable on my monitor while shooting even when magnifying.

I just can’t expect others to always Key this out of my footage in post.

I’m going to try shooting some tests in r3d HQ shortly to see if that helps.

[Michael Tiemann]

Here is a link to one of the R3D's. Let me know what ya'll think. Worth noting this is R3D LT.

Its a wild a neon peaking effect. It's visible on edges against the sky in every backlit exterior shot Ive done regardless of stop.

https://drive.google.com/drive/folde...ht?usp=sharing

Confirmed. I put the clip into Resolve, opened up the Vector scope and watched it play. I adjusted color temp to 7000 and tint to +18 just to center the white blob, and with the Vector scope set to 2x zoom, you can really see the fringing come and go as focus and motion blur make certain features sharp or blurry. The last frame of the 2GB clip is one of the brightest in the vectorscope.

Using a qualifier to cut the purple saturation definitely removes the purple fringing, at the expense that one cannot really use purple in that shot without lots of extra secondary grading. Quite surprised at how strong the effect is.

Nevertheless, you can definitely see how much the lens can be to blame if you start at frame 209-214 (where purple fringing is prominent) and step through to 218-221 (where you can see some out-of-focus branches are clearly purple and others clearly green) you can see that the lens is truly splitting the wavelenghts for you, and that whatever you are choosing as your focus point is getting the red/blue stuff in focus and leaving the green stuff out of focus.

[rand thompson]

Rick,

I have been personally experimenting on how Red's change on how Kelvin and Tint reacts in the komodo from the "Planckian Locust" (1700K to 4000K range) to the "Daylight Locust" (5000K and above range) at the different Color temperatures ranges at different times of day. I think all of the image issues some are seeing in the Komodo can partially or completely be contributed to this , but that's just my personal opinion.

[Mike P.]

Rick,

I have been personally experimenting on how Red's change on how Kelvin and Tint reacts in the komodo from the "Planckian Locust" (1700K to 4000K range) to the "Daylight Locust" (5000K and above range) at the different Color temperatures ranges at different times of day. I think all of the image issues some are seeing in the Komodo can partially or completely be contributed to this , but that's just my personal opinion.

Is that a hardware/sensor design change with Komodo, or a colour science/debayer/software-side change for all r3d footage?

[Rick Cook]

At the root of it, the lens is introducing the color.

I just went out with three lenses at 50mm, this FD, CP2 and a Canon 24-70mm at 50mm at 2.8. The L series Zoom does a good job but I still get the neon purple hits. Its no doubt aberration causing it I'm just trying to work though what can help with it. As Mike P said I am feeling like its a perfect storm that exacerbates the lens's artifacts into something much more unpleasant. I'm more surprised others are not having the issue, which is the main reason I posted here. On most of my footage I can zoom in and find neon purple hits.

[rand thompson]

Mike,

I'm trying to figure that out myself. But if I had to make a guess, I would say Sensor. The reason, because all existing IPP2 Output Transform luts work fairly well with Komodo. Maybe IPP2 Transform Luts specifically aimed at how the Komodo reacts at certain color temperatures are needed.