I have a problem where lights (taillights and even inside on car gauge dials, the light is not red but purple. Anyone have any idea what could be the problem? I am using 5d MkII with 17-40, white balance is automatic. I am shooting hundrets of cars and editing one by one is a big job. Thanks for your anwsers in advance.
belive me I tried. Bought a CPL and UV filter, nothing. Tried underexposing with CPL and still the same. Did recently a video with a new car. Still purple. Starting to think it is sensor issue. Not that it is broken, rather it is the problem with new LED-s.
I'm still seeing color channels clipping. The lights are quite bright compared to the exposure needed for the rest of the vehicle.
You may have have to use some HDR.
See:
I'm sampling the pixels in the tail light and both the blue and red channels are clipped.
When I do the vehicle to the left (where the tail-lights look more red), the red channel is clipped, but not the blue or green.
Either way, this changes the hue. For something to look properly "red", you should see a strong red value (but not clipped) and a low blue and green value.
When your red channel is 255 (which is clipped .. that's the max value of an 8-bit JPEG), but your blue channel is also 255 (also clipped) you now have equal amounts of red & blue. Red + Blue = Violet. The "green" channel brightens up the violet to something that looks a bit more magenta.
Basically this means your tail lights are *really* bright compared to the rest of the vehicle. The exposure that nicely exposes the car is completley over-exposing the lights.
If you spot meter the tail-light (even if that means walking the camera lens up to the tail-light so you are just inches away) and take a meter reading. That would be a "middle" exposure for the tail-light (for a camera, that's usually 12%). The tail light should be bright (just not blown out) -- so you can shoot a few stops above that exposure, just make sure you check the RGB values to verify that no channel is blown out (nothing is reading 255).
From there you can shoot an additional shot metered for the whole car (you'd want the camera on a tripod so nothing moves) and then merge those via Photoshop (or any HDR software.)
What you are doing is a bit tricky ... so don't feel bad that you've been having a hard time with it.
Other things you can do is put a circular polarizer on the lens and rotate it while watching the reflections on the car. Rotating a polarizer will dial the reflections up or down. I usually don't like to *completely* kill the reflections (or the card wont look shiny) but I try to tame them down so they aren't a distraction.
@TCampbell wrote:I'm still seeing color channels clipping. The lights are quite bright compared to the exposure needed for the rest of the vehicle.
You may have have to use some HDR.
See:
I'm sampling the pixels in the tail light and both the blue and red channels are clipped.
When I do the vehicle to the left (where the tail-lights look more red), the red channel is clipped, but not the blue or green.
Either way, this changes the hue. For something to look properly "red", you should see a strong red value (but not clipped) and a low blue and green value.
When your red channel is 255 (which is clipped .. that's the max value of an 8-bit JPEG), but your blue channel is also 255 (also clipped) you now have equal amounts of red & blue. Red + Blue = Violet. The "green" channel brightens up the violet to something that looks a bit more magenta.
Basically this means your tail lights are *really* bright compared to the rest of the vehicle. The exposure that nicely exposes the car is completley over-exposing the lights.
If you spot meter the tail-light (even if that means walking the camera lens up to the tail-light so you are just inches away) and take a meter reading. That would be a "middle" exposure for the tail-light (for a camera, that's usually 12%). The tail light should be bright (just not blown out) -- so you can shoot a few stops above that exposure, just make sure you check the RGB values to verify that no channel is blown out (nothing is reading 255).
From there you can shoot an additional shot metered for the whole car (you'd want the camera on a tripod so nothing moves) and then merge those via Photoshop (or any HDR software.)
What you are doing is a bit tricky ... so don't feel bad that you've been having a hard time with it.
Other things you can do is put a circular polarizer on the lens and rotate it while watching the reflections on the car. Rotating a polarizer will dial the reflections up or down. I usually don't like to *completely* kill the reflections (or the card wont look shiny) but I try to tame them down so they aren't a distraction.
I'm pretty sure that DPP allows you to dminish the blue and/or green channels without affecting the red. I'd be really surprised if Lightroom/Photoshop didn't let you do so as well. In an image as dark as this one, the rest of the car wouldn't know the difference.
