As the saying goes, “There’s no such thing as a free lunch.” And it looks like this applies to camera tech as much as anything else. According to a new report, the Sony a9 had to sacrifice some dynamic range to reach the crazy 20fps speeds everyone is so excited about.
The report comes from DPReview, who performed their ISO Invariance test during Sony’s multi-day launch event in NYC.
For this test, reviewer Rishi Sanyal takes several frames with the a9 at the same shutter speed and aperture settings, but with different ISOs. Then he takes the photos into post and equalizes the brightness of the RAW files. In this way, he’s able to determine where the sensor’s noise floor is, revealing the camera’s dynamic range.
The conclusion is a bit disheartening:
It’s immediately obvious the a9 is not ISO-invariant. This means the camera is adding a fair amount of read noise that results in noisy shadows, limiting dynamic range at base ISO.
It’s not the typical performance we’ve come to expect from Sony sensors and we suspect the higher readout speed is leading to greater noise. In other words, it appears this sensor was likely optimized for speed at the expense of low ISO dynamic range.
As a result, DPR suggests you do NOT shoot this camera below ISO 640 and then try to recover shadows in post… you’ll be disappointed. To see exactly why, check out the full report and sample images over at DPReview.