75LVR color shift

[J-KNIGHT]

Having a problem that is showing on every frame I bring into eXposure from my 75LVr's CF card. On each frame, the right side is warm green while the left half is neutral. The shift is subtle (but noticeable) and fairly abrupt right down the middle. Any help would be appreciated.

[filmcapture]

What lens do you use?

[ThierryH]

Having a problem that is showing on every frame I bring into eXposure from my 75LVr's CF card. On each frame, the right side is warm green while the left half is neutral. The shift is subtle (but noticeable) and fairly abrupt right down the middle. Any help would be appreciated.

Dear j-Knight,

it has to do with the sensor's non-linear response, and that the default ref. files from Sinar are done without lens (sensor shading). A solution to overcome this problem is to make another default ref file with e.g. a standard 80mm lens at e.g. f 8 and to use this reference for all shots, with all lenses. It will by far be better than any default ref file provided by the manufacturer.

Best regards,
Thierry

[J-KNIGHT]

Dear j-Knight,

it has to do with the sensor's non-linear response, and that the default ref. files from Sinar are done without lens (sensor shading). A solution to overcome this problem is to make another default ref file with e.g. a standard 80mm lens at e.g. f 8 and to use this reference for all shots, with all lenses. It will by far be better than any default ref file provided by the manufacturer.

Best regards,
Thierry

Thanks for your help.  Exactly how do I create and then apply the new reference file?  You can reach me at:   [email protected]
Is there a Sinar publication that details the exact steps in creating and applying the file?

[bdp]

It's all in the help file. But basically - when tethered press command-p then take a shot with a piece of white opaque plexiglass over the lens. Save this shot with a name that records the lens and aperture then you can select this from the capture tab when shooting in the future to apply it to every subsequent shot. This is different from the 'shading mode', which is for retrospective application of shading files when shooting to CF card. That is where the shot taken with the plexiglass is organised in the contact sheet before the shots you want to apply it to, then you enter shading mode to select which files have that shading file applied to them. Great for tech cameras where lens movements or stitching can create differing colour casts. You should probably make the exposure with the plexiglass 1 or 2 stops brighter than the shot without by using the shutter speed, not aperture, so that the shading file is bright, but overexposed to the point of clipped highlights.

Ben

[ThierryH]

It's all in the help file. But basically - when tethered press command-p then take a shot with a piece of white opaque plexiglass over the lens. Save this shot with a name that records the lens and aperture then you can select this from the capture tab when shooting in the future to apply it to every subsequent shot. This is different from the 'shading mode', which is for retrospective application of shading files when shooting to CF card. That is where the shot taken with the plexiglass is organised in the contact sheet before the shots you want to apply it to, then you enter shading mode to select which files have that shading file applied to them. Great for tech cameras where lens movements or stitching can create differing colour casts. You should probably make the exposure with the plexiglass 1 or 2 stops brighter than the shot without by using the shutter speed, not aperture, so that the shading file is bright, but overexposed to the point of clipped highlights.

Ben

... in addition, this, to be found in eXposure "Help":

Best regards,
Thierry