Quote Originally Posted by dancqu View Post
Questions from one who does not use a laser for alignment.
Is that reflecting surface meant to be an exact substitute
for the negative? Is it assumed that the negative and
the reflecting surface occupy the same plane? Dan
Just to elaborate on what the others have pointed out.

The IMPORTANT alignment is between LENS and NEGATIVE and the baseboard is not so critical (especially at high magnification). HOWEVER, there is no easy way to get the laser between the lens and the negative stage so the usual practice is to align negative stage (or carrier) to the baseboard, then align the lens to the baseboard. In general, a optical glass is used as the reflecting surface (like a microscope slide) and it is either positioned on the negative stage or carrier, or held on the front rim of the lens. In practice, I usually just put a glass negative carrier in the negative stage and reflect off of that.

Just to elaborate on another technique I use; I have found the concentric rings of the diffraction pattern that occurs when the laser is pointed directly in to the center of the lens may be a better indication of lens centering than the front rim of the barrel. This is especially true on my 30mm Rokkor used for Minox and 16mm. The front of the lens barrel is the aperture ring, and it has a little wobble in it.