a57 v d5100 for first DSLR

Started Apr 6, 2013 | Questions thread
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Leonard Migliore
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It lets the camera focus
In reply to Bjorn_L, Apr 9, 2013

Bjorn_L wrote:

123Mike wrote:

That is your hypothesis. I have another: the sensor is more sensitive to begin with.

Amusing theory given that they use the same sensor.  The a57 just gives up 1/3 to 1/2 stop due to their puzzling use a old technology called a Translucent Mirror.  It is possible to have an EVF without this loss (such as Olympus and Panasonic do).  I don't understand what advantage Sony thinks they get with this approach.  The viewfinder in the gh2, for example, compares favorably to the Sony ones I have seen.

The mirror in the SLT is, obviously, not used to look at the image since the EVF runs off the sensor as it does with all mirrorless cameras. It is, rather, used to allow phase detection autofocus like SLR's have. Phase autofocus is much faster than contrast autofocus, which is used by other mirrorless systems.

So it's a kluge, but it replaces another and more massive kluge, the reflex viewing system. I would expect all this stuff to be gone when on-sensor phase detection becomes more mature.

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Leonard Migliore

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