FS7: Weird Pattern when Shooting Flares

Mike K

Mike K

Active member
Hey guys, I just received 2 FS7's for a doc I'm shooting over the next 2 months. I took them out yesterday to do some tests and got these weird boxy patterns whenever the lens was hit with a flare or direct source. I'll be shooting most of the doc in concert venues so this issue is a big concern for me. Anyone have any idea what could be causing it? (stills below)

Settings were

4K/60p
1/125th
Rokinon 35mm w/ Metabones Canon EF to E adapter

Higher Res Still:
https://www.flickr.com/photos/129107244@N07/16322340786/

FS7_Issue_W.jpgFS7_Issue_M.jpgFS7_Issue_C.jpg
 
My only solution is to use the right lens.
Canon 24-105 on speedbooster is a flaremachine!

I use the cheapo Canon 17-55/2,8 on a standard Smart Adapter.
It's much better!
 
Short answer from the extended reading:

Problem is sensor related to extreme overexposure. Likely impossible to overcome regardless of codec or debayer method. Solution is the reduce the degree of overexposure, either by exerting lighting control to limit dynamic range or by stopping down to better protect highlights and the expense of your darks.


EDIT: To clarify - some codecs and debayer methods may reduce the effect, but may not completely resolve the issue.
 
Last edited:
If the problem is only related to sensor overexposure, why is it I haven't recognized it.
This was from my very 1st test, where I stressed the camera to the max:

flare-test01.jpg

100%
flare-test01_ex.jpg




Shot in cineEI (S-Gamut3.cine/SLog3) @800ISO
QFHD/25p XAVC-I @250MBit
1/50s
Canon EF-S 17-55 @55mm+f4.8

I think the problem is part of the remapping to the file and therefore the gamma/paint settings will make some difference here.
 
The "grid" pattern only shows occasionally, and with that, only at certain angles where bright source (sun) hits the sensor at a particular angle. Alsiter Chapmen has remedied this effect with simple matting of the sensor (not exactly sure how he did it)

I also noticed that when I shoot RAW, choosing sony debayer instead of Resolve debayer minimises the effect and deals with it better.
 
There have been similar issues with the BMC cameras under similar flare conditions. It happens when extreme off angle light flares outside the frame wash an underexposed or deep shadow area of the image, bringing up fixed pattern noise that would otherwise be lost in black. Controlling the angle of light striking the lens with a matte box helps.
 
I've run into this issue here and there with the FS700 as well. I just got the FS7 so I cannot comment.

The weird thing is that it mostly shows up in Resolve. I can take the same clip and put it in After Effects and the grid is not there. I think the way Resolve and After Effects interprets the footage is different. i know there's some perimeters in Resolve that you can mess around with that can make it go away. I just did the easy thing and switch to After Effects for the messed up shots.
 
gene_can_sing said:
I've run into this issue here and there with the FS700 as well. I just got the FS7 so I cannot comment.

The weird thing is that it mostly shows up in Resolve. I can take the same clip and put it in After Effects and the grid is not there. I think the way Resolve and After Effects interprets the footage is different. i know there's some perimeters in Resolve that you can mess around with that can make it go away. I just did the easy thing and switch to After Effects for the messed up shots.
Click to expand...

useful tip thanks for sharing.

Surinder.
 
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