Sony SLT camera explained

Single-lens translucent (SLT) is a Sony proprietary designation for Sony Alpha cameras which employ a pellicle mirror, electronic viewfinder, and phase-detection autofocus system. They employ the same Minolta A-mount as Sony Alpha DSLR cameras.[1]

Sony SLT cameras have a semi-transparent fixed mirror which diverts a portion of incoming light to a phase-detection autofocus sensor, while the remaining light strikes a digital image sensor. The image sensor feeds the electronic viewfinder, and also records still images and video on command. The utility of the SLT design is to allow full-time phase-detection autofocus during electronic viewfinder, live view, and video recording operation.[2] [3] With the advent of digital image sensors with integrated phase-detection, the SLT design is no longer required to accomplish this goal, as evidenced by cameras such as the Sony NEX-5R, Fujifilm X-100s, and Nikon 1,[4] [5] although the SLT design avoids having pixels unavailable for image formation due to their space on the sensor being occupied by a dedicated phase detection autofocus sensor.

The term "translucent" is a misnomer for the actual SLT design, which employs a pellicle mirror that is not translucent. Pellicle mirrors have been used in single-lens reflex cameras from at least the 1960s (see Canon Pellix) and in the Pentax EI2000/Hewlett Packard 912 digital SLR of 2000 which used an optical viewfinder and on-sensor contrast-detection focussing.

List of SLT cameras

Model Announcement Megapixels Sensor Screen Built-in flash
2010 14 MP 3" articulated (pop-up)
2011 16 MP 3" fixed (pop-up)
2012 16 MP 2.7" tilting (pop-up)
2010 16 MP 3" articulated (pop-up)
2012 16 MP 3" articulated (pop-up)
2013 20 MP 2.7" tilting (pop-up)
2011 24 MP 3" articulated (pop-up)
2015 24 MP 2.7" tilting (pop-up)
2011 24 MP 3" fully articulated (pop-up)
2014 24 MP 3" fully articulated (pop-up)
2012 24 MP 3" fully articulated
2016 42 MP 3" fully articulated

All of the above cameras record 1920x1080 video at 60i/30p (NTSC regions) or 50i/25p (PAL regions), in MPEG-4, AVCHD or H.264 formats. The Alpha 65 and 77 also records video at 50p or 60p, and the Alpha 99II records 4k video at 100 Mbit/s (using XAVC S) with full sensor read-out.

Source: summarised from the full comparison table at DP Review.

See also

Notes and References

  1. Web site: Lenses for Translucent Mirror cameras. Sony.com .
  2. Web site: Sony Single-Lens Translucent Cameras . KolariVision.com.
  3. Web site: Mirrorless Cameras: A Primer . December 15, 2011.
  4. Web site: Fujifilm's phase detection system explained . Digital Photography Review.
  5. Web site: Nikon V1, J1: Two new compact system cameras for Nikon's mirrorless debut . Mike Tomkins . Imaging Resource.