Help! - K-5 entering its Blue Period ( intermittently photos == cyan )

Started Apr 9, 2014 | Discussions thread
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BobORama Senior Member • Posts: 2,486
Help! - K-5 entering its Blue Period ( intermittently photos == cyan )


I did a series of shots today with a Sigma 10mm / 2.8 - which I acquired recently. The camera was powered off / on a few times during the session, so the issue persisted between them.

I did a time lapse last night with the lens, and got ~5000 shots out of it all were properly exposed ( though I hosed up the focus, so its garbage. )

On checking the images, Green looks proper, Red and Blue look way off, curve wise. And it varies from shot to shot within the same bracket some times, so I could not have changed the settings.

Is there some way in which the lens is causing this bad behaviour?

Based on what I know about the readout of the image data, there is not a mechanism by which only the red or blue components would be miss-read - as its all the same circuitry, and the problem covers the whole sensor, which discounts one of the DAC's or amps failing. Its almost as if WB is horribly messed up. I don't have RAW for these... so I cannot see if the issue is sensor or in WB.

Take a look here:

I appreciate your thoughts.

 BobORama's gear list:BobORama's gear list
Pentax K-5 Pentax K-1 Sigma 10mm F2.8 EX DC HSM Diagonal Fisheye Pentax smc DA 18-55mm F3.5-5.6 AL WR Samyang 14mm F2.8 IF ED MC Aspherical +9 more
Pentax K-5
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