Re: Double vs Single Condenser Lens

A R wrote:
> I've started taking 6x6 photos. Instead of buying a new enlarger, I'm
> adapting my trustworthy MPP condenser to take 6x6 negs. This has
> involved fabricating a new lens board, fabricating a new neg holder,
> purchasing a new enlarging lens and replacing the condenser.
> 
> Now, I have a pair of spherical condenser lenses but unfortunately I
> have no cell to mount them in. A single lens on its own fits snuggly in
> the enlarger head and seems (by eyeball) to give a uniform illumination
> across the easel.
> 
> I know some enlargers use single apsherical lenses but what
> advantage/disadvantage do I have using a single spherical lens?
> 
> Come to think of it, I'm not to sure why condenser lenses come in pairs!
> 
> 
The double condenser;
-shortens the focal length of the condenser a lot
-the symmetry cancels our most spherical aberration  (make the light 
more efficient and even)