auto white balance wildly different for Fuji / Rokinon lens

[jbreiden]

Camera is Fuji X-T2. Manual focus, aperture priority, aperture f/6.3.  White balance is in the default automatic setting, and is coming up with radically different solutions for the two lenses. Rokinon results are much more color accurate. Any idea what is going on?

 

Settings are factory default except:

SET UP > BUTTON/DIAL SETTING > SHOOT WITHOUT LENS : ON

SET UP > POWER MANAGEMENT > PERFORMANCE : BOOST

SET UP > POWER MANAGEMENT > AUTO POWER OFF : OFF

SET UP > CONNECTION SETTING > PC SHOOT MODE : USB AUTO

SET UP > SHOOTING SETTINGS > SHUTTER TYPE : ES

MF/AF > MF ASSIST > FOCUS PEAK HIGHLIGHT > RED(LOW)

 

Fuji "smart" lens:

Lens Info                       : 56mm f/1.2

Lens Make                       : FUJIFILM

Lens Model                      : XF56mmF1.2 R

 

Rokinon "dumb" lens:

Rokinon RK50M-FX 50mm F1.2 AS UMC High Speed Lens Lens for Fuji 

 

 

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Edited August 10, 2017 by jbreiden

[Vidalgo]

On 1st image red channel is clipped a bit, as comparing to 2nd. And overall exposure shifted to right side.

May be worth to repeat test with negative exposure correction for first lens.

Edited August 10, 2017 by Vidalgo

[jbreiden]

This difference is reproducible across multiple Fuji X-T2 cameras, and multiple Fuji & Rokinon lenses.

 

Fuji's 50mm lens acts just like the Fuji 56mm in terms of color. I don't get it.

 

Lens Info                       : 50mm f/2

Lens Make                       : FUJIFILM

Lens Model                      : XF50mmF2 R WR

[CDBC]

I don't know a lot about this (film I know about, digital still a newbie) but to my mind, unless your cards are all showing the same 18% grey background - and I mean, the same grey, same brightness - then trying to draw conclusions about colour saturation or accuracy seems, well, impossible.

 

(OK, now I look forward to being told why my theory doesn't work ... )

Edited August 11, 2017 by CDBC