INSTRUCTIONS TO USE THE BRAINBOX © Arca Swiss
- Determination of aperture and focusing point
1. Move the Brainbox to the rear end of the optical rail with the locking knob
positioned on the right hand side. Focus to the near point.
2. Drive the Brainbox to the rear function carrier until you have contact with it.
Move the knob on the right hand side of the Brainbox downwards and, still holding the knob, focus to the far point.
3. The reading for the correct aperture appertaining to the depth of field for
your format and degree of magnification can now be taken (¼ or ∞).
4. Take the reading for the extension factor on the right hand side of the
brainbox and focus to the middle of the two focusing points (i.e. half the extension).
5. The sensor is re-locked by reversing the Brainbox back to the near focusing point.
- Determination of the tilt angle for the camera back
1. Cut the template supplied to fit your camera format and trace the square to the
groundglass with a waterproof pen. The centre of the groundglass is the
2. Instead of focusing to the near and far points, focus now to the newly
marked H-base lines (57mm or 114mm). The top line corresponds to the near point, the
bottom line relates to the far point. Proceed as described above. The extension factor
shown on the right of the Brainbox, will result in the following swing/tilt ratios:
Base line 57mm: (format: 6x9cm - 4x5") 1mm = 1.0°
Base line 114mm: (format: 5x7" - 8x10") 1mm = 0.5°
The sensor is re-locked by reversing the Brainbox back to the near focusing point.
Please note: According to Th. Scheimpflug's principle, the tilt and swing angle are not
identical for the rear and front standard and can therefore not be translated