Quote Originally Posted by Donald Miller
My experience has shown the Callier effect lacks validity. If you haven't tried this for yourself, then I encourage you to determine the accuracy of these statements without simply accepting either Ansel Adams or Fred Pickers pronouncements.
Don,

the so-called Callier Effect is a reduced transmission thru silver based film, due to light stray. It depends mainly on the aperture of the light source. It is a matter of fact that a condenser enlarger produces a higher contrast than a color head with diffuse light. This *is" the Callier Effect. However, some photographers believe, that the Callier Effect also affects the shape of the density curve (i.e. that the effect changes over density and can, e.g., improve shadow detail). This isnít necessarily the case in practice.

Apart from the aperture of the light source, the Callier Effect is dependent on:
- grain size and shape
- aperture of the enlarger lens
- film gamma and density

However, the impact of gamma and density is usually much smaller than that of the light source. The effect of grain, gamma and density are much depended on the film type. We have to take into account, that modern film has different characteristics than the one used by former masters. So we may come to different conclusions today.