There is optical alignment and there is vertical alignment of the light source, negative and lens. Frequently these adjustments involve tweaking the little bit of play that exists in light boxes, and negative carriers to get things lined up.
The steps involved would be like using a laser alignment device to see the diffraction pattern off the lens and get the optical center of the lens. Then make a big X centered on that spot on the baseboard. Then take the negative carrier out and see that the projection of the light source borders are the same distance from the center of the X. If not then shift the head, lightbox or the lensboard to get them aligned. Then put the negative carrier in and see that the projected corners are all the same distance from the center of the X. Even high-end large format enlargers can have very little leeway when using them for full-frame printing of the the maximum negative size. This is just one method. Like optical alignment, there are a lot of ways to get the job done.
I have shop manuals and service manuals for all my enlargers and this type of alignment is not discussed in those manuals. (Some manuals do cover it in brief ie the Chromega-D manual).
Last edited by ic-racer; 06-18-2009 at 03:58 PM. Click to view previous post history.