True Focus and Absolute Position Lock
True Focus helps solve one of the most lingering challenges that faces serious photographers today: true, accurate focusing through- out the image field. Without multi-point auto-focus a typical auto- focus camera can only correctly measure focus on a subject that is in the center of the image. When a photographer wants to focus on a subject outside the center area, they have to lock focus on the subject and then re-compose the image. In short distances espe- cially, this re-composing causes focus error, as the plane of focus sharpness follows the camera’s movement, perpendicular to the axis of the lens.
The traditional solution for most DSLR cameras has been to equip the camera with a multi-point AF sensor. These sensors allow the photographer to fix an off-center focus point on an off-center sub- ject, which is then focused correctly. Such multi-point AF solutions are often tedious and inflexible to work with. Due to the physics of an SLR-camera, the off-center focus points that are offered are all clustered relatively close to the center of the image. To set focus outside of this center area, the photographer is still forced to focus first, and then shift the camera to reframe, with the resulting loss of focus as a result.
To overcome this problem, Hasselblad has used modern yaw rate sensor technology to measure angular velocity in an innovative way. The result is the new Absolute Position Lock (APL) processor, which forms the foundation of Hasselblad’s True Focus feature.
DIGITAL CAMERAS
Wi-Fi
The APL processor accurately logs camera movement during any re-composing, then uses these exact measurements to calculate the necessary focus adjustment, and issues the proper commands to the lens’s focus motor so it can compensate. The APL processor computes the advanced positional algorithms and carries out the required focus corrections at such rapid speed that no shutter lag occurs. The H5D’s firmware then further perfects the focus using the precise data retrieval system found on all H System lenses.
The plane of focus changes when the camera is tilted for composition.
