I sent them just the first flight file of 4GB using a share with Google Drive - it's limited to 10GB so I would not be able to send all four files anyway. Here's the text of my email that accompanied the video file.
DJI_0001.MP4
Gentlemen,
In the YouTube video that you refer to (
)
I refer to several issues I have with the
P4P and I have attached one of the four files of the flight in question. In it you will see the blown highlights in the sky and also the flickering/pulsing artifact that occurs every 30 frames -- flickering most obvious from about 3:30 onward, while flying over the pond. So, let me start at the beginning.
1. The camera settings were D-Log, with a custom setting of -2/-2/-2 for sharpness, contrast and saturation. The exposure was controlled manually with 30fps, f/6.3, ISO100 and a shutter speed determined partly by the Go app histogram and partly by the observation of the video feed.
2. It is always difficult to see the Go app screen when working in bright daylight even with the brightness turned all the way up on my Samsung tablet. When using D-Log in particular the washed out screen is even more washed out due to the DR compression of D-Log making it even more difficult to see the video feed on the Go app. This makes confirming critical focus and exposure very difficult.
3. I set the exposure first by looking at the video feed and then checking the histogram. The histogram looked very low so I adjusted the exposure up a bit and then the feed looked over exposed so I reduced it half way between those points. At this point the peak value in the histogram was less than 75 indicating no clipping and that the exposure was pretty far away from clipping the highlights. The min value was about 20 indication there was no crushing of the blacks.
4. I reviewed the video in Adobe PP CC and found the problems mentioned in the video with terribly blown highlights even the the Go app histogram did not show that the exposure was any where near clipping. I also noted the flickering/pulsing problem and verified it occurs every 30 frames. You can single step the video and when going from frame 29 to frame 0, every second, you see the Lumetri scope indicate a jump in the values.
5. This flickering problem is not limited to the new
P4P and also exists with the Inspire 1 Pro with X5 camera. I own both the
P4P and the I1 Pro and this flickering problem occurs with both cameras. I have found that the flickering issue becomes more noticeable after doing contrast stretching in post and the more you stretch the contrast the more visible the flickering. D-Log requires a large amount of contrast stretching and seems to produce the greatest amount of visible flickering in the final output.
So, my feeling is that D-Log is not properly handling contrast and that data is being lost. However, even if this turns out not to be the case the operational problem is that it is so hard to determine proper exposure and critical focus when using D-Log due to the washed out screen. Also, the flickering effect is made worse when using D-Log due to the contrast stretching amplifying the artifact.
You will note that I have posted two more videos with the
P4P that are not as critical and demonstrate that even with the image processing problems it's still possible to get good video. In this video (
) I shoot using D-Cinelike and was able to get much better exposure because the histogram was more accurate and it was easier to see the video feed. My last video (
) was also shot using D-Cinelike with a custom setting of -1/0,-1 and also using the new firmware from 09Dec2016. Exposure was once again manual with f/5.6, ISO100 and a shutter speed that was 1/1000 throughout.
For me the biggest problem is the flicker issue but I would also like to see D-Log improved both from a functioning standpoint and an operational one. The Go app histogram needs to be useful to help set the exposure because the video feed, being so washed out, makes visual adjustment of exposure very difficult.
Thank you,
Brian Stirling