a57 v d5100 for first DSLR

Started Apr 6, 2013 | Questions thread
Leonard Migliore
Leonard Migliore Forum Pro • Posts: 16,483

Fat Dragon wrote:

Wally626 wrote:

Checked my A77 versus a light meter in a very unscientific test.

Camera multi spot mode says 1/50 at f/2.8 ISO 1600

Camera spot meter mode on small 18 percent grey card centered in the scene says 1/15 at f/2.8 ISO 1600

Incident light meter says between 1/30 and 1/60 at f/2.8 ISO 1600

In the image the one using the camera spot meter was too bright the multi spot and incident meter shots were exposed corectly. Base on rough approximation the meter was probably about 1/40 versus the 1/50 the camera gave so pretty close.

The Sony camera is probably calibrated for a 12 percent gray card which would be why the scene was a bit over exposed using an 18 percent gray card.

To help a layman out, would this test indicate differences in actual ISO levels between various cameras, or simply a different approach to metering in the SLT as compared to an SLR or incident light meter?

Most recent Sony sensors are "ISOless', meaning that their noise levels do not depend on the selected ISO. So all the test indicates is the level of amplification of the sensor signals to produce a specific brightness level on a JPG. Which is something only of significance to the sensor electronics designer and his priest.

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Leonard Migliore

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