Recently we released a video testing the BMPCC 4K and comparing it to some similarly priced, mirrorless cameras. Now in our testing, the BMPCC 4K didn't perform as well as the other mirrorless cameras, when exposing 3 stops over. Which was strange, at 1 and 2 stops over, the camera performed brilliantly, so we decided to take a closer look.
Performance 'Issues' Explained
Now to first understand why this was happening, it's important to understand our testing methods. Our aim with these tests, was to find out, how each camera performed in the same environment, using the same settings with the same lighting conditions. During our previous tests, every camera we tested was subject to the same settings and by no means did we shoot the scene with the cameras in a way which would have best suited that camera. The BMPCC 4K was no exception here. The settings were as follows:
- 0 Stops/ 'normal' exposure - ISO 400, T2.8, shutter 1/50
- + 1 Stops ISO 400, T2, shutter 1/50
- + 2 Stops ISO 800, T2, shutter 1/50
- + 3 Stops ISO 1600, T2, Shutter 1/50
If you didn't already know, the BMPCC 4K has a dual native ISO (400 & 3200), meaning that there are two analogue circuits on the sensor for the ISO. By switching from ISO 800 to ISO 1600, we were switching to the higher ISO circuit where there is less dynamic range in the highlights.
Many people were commenting, that if we had shot the tests at ISO 400, or in RAW, we would have had better results, and from our tests above, we found just that. From our tests, using ISO 400, we found that the BMPCC 4K performed much better, and handled overexposure at +3 stops, much better than when it was at ISO 1600. And when it came to the second native ISO 3200, it too performed better than in our original tests at 1600. At ISO 3200 the camera didn't perform as well as ISO 400, but it was definitely a step up from our first test.
Now we also tested how the RAW compares to the Prores. Here when using the highlight recovery option in Davinci Resolve, we were able to pull back almost an extra stop of information than in the Prores. What's interesting, however, is when not using highlight recovery, we couldn't see a difference between the RAW and the Prores. The highlight recovery in Resolve, is really where the difference is here. For the most part, it works great, and drastically changes the shot and saves a lot of information. When you look at ISO 1600 with highlight recovery, there is something really strange going on with the image. The areas that are clipped are going a little orange, this does happen slightly with the other ISO's but nothing this extreme. If you look at the colour chart, all the colour seem off with a slightly more saturated, orangey tint to them.