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The Sony A9’s PDAF array is linear — it detects vertical contrast well but struggles with horizontal contrast like a bird in profile, unlike the Olympus EM-series cameras which use cross-type sensors that detect any pattern orientation equally. This structural limitation, combined with the 200-600mm’s single focus motor and 2.1kg weight, explains why the A9 hit only 39% accuracy in the demanding afternoon session at the Hawk Conservancy Trust against the EM1x’s 45%.

Full-frame cameras used in APSC crop mode lose their full-frame noise advantage entirely — the cropped area has the same noise characteristics as a native APS-C sensor, which is identical to the Olympus cameras. Since the OM system’s faster lenses cancel out the remaining sensor noise difference in direct comparisons at matched apertures and focal lengths, the noise case for choosing full-frame over Olympus for birds in flight effectively disappears.

The EM1x’s noise at matched focal length and aperture is within 0.5 stops of the A9’s, and at ISO 3200 and above where birds-in-flight shooting actually occurs, the gap is negligible after standard denoising. The reason Olympus users perceive worse noise is usually that they are comparing against full-frame cameras with faster lenses — once the comparison accounts for matched apertures and magnification, the EM1x frequently looks cleaner in real-world files.

Matching the EM1x and A9 at equivalent subject magnification and aperture — rather than at the same focal length and ISO, which is the comparison most reviewers use — shows the two systems within 0.5 stops of each other at ISO 3200. The perceived noise advantage of Sony full-frame is largely an artefact of unfair comparison conditions that favour the larger sensor by ignoring how much more light the smaller-sensor OM lenses gather per pixel.

At base ISO, the A9 has 1–2 stops more dynamic range than the EM1x, but at ISO 3200 where birds-in-flight shooting typically occurs, the difference narrows to around 0.5 stops — negligible for most subjects. The 1.3-stop lens speed advantage of the OM pro telephoto lenses over the Sony 200-600mm effectively eliminates any remaining DR gap in practice when the comparison is made at matched apertures.