Alpha 910 — Full-Frame Camera Bodies Compared | alpha910.com

What the sensor line tells you about motion

A global shutter reads the whole sensor at once, which removes rolling-shutter distortion from stills and video.

A rolling shutter reads the sensor row by row. Each row records a slightly different instant, so a bat, a ball or a splash comes out skewed or bent.

The Alpha 9 III reads the entire sensor in one go, and Sony reports distortion-free capture of fast action in stills and in video.

The same read-out changes flash work: synchronization is possible at shutter speeds up to 1/80,000 second, well past the sync limit of a focal-plane shutter.

• Sensor resolution, in megapixels
• Maximum shutter speed, in seconds
• Continuous burst rate, in frames per second
• Video frame rate and bit depth
• Stabilization compensation, in CIPA stops

Reading a specification sheet in order

Five checks in the order the sheet presents them, each one named for the failure it catches.

Start at the sensor line: size in millimetres, resolution in megapixels, then the read-out type if the sheet names one.

Next comes the shutter line. Record the fastest speed and the conditions attached to it, because a ceiling can be switched off.

Close with stabilization and video. Stops only compare when the sheet says CIPA, and video needs frame rate and bit depth together.

• Sensor line — failure: resolution quoted for a cropped mode instead of the full frame
• Burst line — failure: frames per second quoted without AF/AE tracking or with blackout
• Shutter line — failure: 1/80,000 s switched off in movie mode, with Var. Shutter, or with no lens
• Stabilization line — failure: stops quoted without a CIPA reference, so brands cannot be compared
• Pre-shot timing — failure: no Pre-Capture, which records up to about one second before the shutter is pressed

Which figures are standardised

Resolution, seconds, frames per second, bit depth and CIPA stops are standardised; the rest is phrasing.

A megapixel counts the same way on any sheet, and a frame per second is counted the same way too. Those lines compare directly between brands.

CIPA stabilization stops follow a published test method, so eight stops on one body means what eight stops means on another.

Phrases such as blackout-free, distortion-free and world's first describe behaviour rather than a measured unit. Treat them as claims to check.