Tag: power zoom

The Sony NEX system collapsible zoom will be an f/3.5-5.6 design focusing to 0.3m if specifications accidentally included with the information on the NEX-5R are accurate. And it will be a power zoom, we think.

The Sony.com info includes in the camera specification this line:

“AF Illuminator : Built-in, LED type (with a range of approx. 0.3-3.0m (with E PZ16-50mm F3.5-5.6 OSS attached))”

This is not the existing 18-55mm OSS lens shown on the camera product shots, or included in the list of compatible lenses. The clue is in the name, E PZ instead of just E or SEL. The 50mm could easily be a typo, but combined with the different focus range (down to 30cm instead of the 25cm minimum) we think this reference is definitely to a new compact, collapsing 16-50mm f/3.5-5.6 power zoom.

Those who are hoping for an f/2.8 might indeed get one of a different type,  but this specification looks competitive as a replacement for the 18-55mm, and not unlike the Olympus/Panasonic Micro FourThirds 14-42mm collapsible power zooms.

All the stocks of the NEX-5R currently being offered, and all the samples apparently previewed by the press, have been fitted with the old (existing) 18-55mm OSS lens.

Here is the page on which you will find, under the specs for the AF illuminator only, the reference to the previously unannounced E PZ lens model:

http://store.sony.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10551&storeId=10151&langId=-1&productId=8198552921666484205#specifications

Here is a page listing all the current compatible lenses (expand to view 10):

http://store.sony.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10551&storeId=10151&langId=-1&productId=8198552921666484205#compatability

It is worth noting that the Phase Detect PDAF system of the NEX-5R could reduce the true resolution of the central focus zone by as much as 20% locally (vertical) and raw image interpolation will restore the integrity of the images despite 99 focus points, each one of which uses three different sensel-based phase detect pixel pairs to cope with the range of exit pupil positions found on different lenses. Since the outer zone of any image is usually slightly lower resolution than the centre, the effect will be to make the NEX-5R more even in sharpness/resolution across the frame but lacking the very sharp centre zone normally found.

Added: we calculate that the PDAF uses 594 single pixels at the minimum based on three pixel pairs (one for each of three exit pupil positions) per AF point.

Effective PDAF depends on the camera knowing the actual design of the lens, because the focus distance and the rear exit pupil (rear nodal point and exit pupil diameter) are both needed for the camera to switch seamlessly to the correct pitch of on-sensor PDAF points. On-sensor PDAF is a bit like the old microprism or split image screens, it depends on a relative darkening of one side or the other of a pair of pixels as focus is changed. It works best close to the lens axis and over a specific range of apertures.

New lenses can be designed to be highly efficient with on-sensor PDAF. On-sensor PDAF has probably been designed to be usable with older lenses. What you probably can not expect from the 5R, or other on-sensor PDAF models, is reliable PDAF using SSM or SAM Alpha lenses on an LA-EA1 adaptor. It may be that it won’t work at all with some Alpha lenses even if they function with contrast detect focusing (and will still use that on the 5R).

– DK