I've just recently started shooting video and stills on a DJI Phantom 4 Pro and have noticed some image gain / noise when reviewing my video footage. I've shot with and without ND filters, usually shooting in manual modeD-Log 2.7K @ 50fps Shutter speed 1/100 ISO 500 (which appears to be locked) I've attached an image with an un/graded comparison. The image noise is more noticeable during the motion. I'm wondering if anyone else has noticed this and has any suggestions. Also, is there a simple fix to unlocking the ISO. For some reason I'm unable to adjust it.

Hi there. Thank you for reaching out and we're sorry for the trouble. D-Log has been improved in the firmware 0418 update. The dynamic range in D-Log becomes larger, and the default ISO is higher due to the change of the gamma curve. In D-Log, when the gain is set to 1, ISO is 500 and the dynamic range is the largest. The sensitivity of the digital camera is determined by gain. It is not related to ISO. ISO is introduced because, with this parameter, photographers use the exposure system for film more easily. The brightness of a digital photo depends on a sensor of which the output signal is in a linear relationship with lights, global digital control, and gamma. Once gamma changes, brightness and ISO change accordingly.

For some cameras, ISO is not set to 100 when the gain is set to 1.
For example, with a normal gamma curve (Rec.709):
Panasonic GH4: 200
Red Dragon: 250
Nikon D600/610: 100
Leica M: 150
SONY RX100: 125

In D-Log, ISO is relatively larger when the gain is set to 1 and only one or some fixed ISO options are available.

However, if the gain of a sensor is increased, the dynamic range will be decreased and noises will become more obvious. So, currently, ISO is set to 500 for optimal dynamic range in D-Log. Whether or not ISO can be set to a higher value will be determined after image quality evaluation and configuration. DJI is working on this. Thank you for your understanding and support.