Quote Originally Posted by MichaelBriggs
Great prints have been made with both systems.
IMO, some of the arguments in Jensen article piece (link provided above by Doug) are nonsense. Comparing shadows cast with sunlight to shadows cast by diffused fluorescent light completly ignores the enlarging lens. After arguments have been made to persuade many readers that sunlight and shadows shows the collimated light sources are superior, the enlarging lens is finally mentioned and conceded to have some role in the process. There is also use of moralistic words rather than technical terminology, e.g., diffusion density isn't "washout", nor is it "flare".
Dead ON!!! There are a number of "cracks" in this article ... one in that he assumes that every lamp merely radiates in all directions - the last time I looked, the EYA Halogen lamp in my D5500 has a built-in parabolic reflector. That serves to "directionalize" - collimate to some extent - the output from the filament. *After* this "raw" light (from either system) passes through the enlarging lens the rays (see "ray trace") follow the same paths anyway ... otherwise there would be no definite focal plane.

The REAL reason to collimate is not to affect "sharpness"; it is to provide even illumination across the focal plane.

I've worked with optical systems with adjustable collimation. To set these up, one removes the projection lens and works the adjusting screws (or whatever) until the lamp filament projected to the focal plane is *centered* and in the best possible focus. That will insure the most even illumination possible over the plane of focus.

A system with condensing lenses - IMHO - n.b. - is NOT clearly and absolutely superior. It is more complex, heavier, more expensive - "feistier" in many ways - and possibly delivers "brighter" light (tad more efficient).

While I doubt the "superiority" I don't think there is an "inferiority" either. It is a matter of ... aesthetics, tastes, superstition ... whatever... a LOT like everything else in photography.