Pixel shift results when a filter in an imaging path has a wedge that alters the angle of a beam of transmitted light, thus causing a shift of the image detected on a high-resolution CCD camera.  When two or more images of the same object acquired using different filter sets are overlaid (in order to simultaneously view fluorescence from multiple fluorophores), any significant non-zero filter wedge angle means that the images will not be registered to identical pixels on the CCD camera. Hence, images produced by different fluorophores will not be accurately correlated or combined. 

The BrightLine ZERO™ option guarantees that the worst-case image shift when interchanging Semrock ZERO sets will be less than ± 1 pixel, measured relative to the mean image position for a large sample of filter sets. 

For further information, please refer to our technical note: What is Pixel Shift?