identifying an Omega enlarger

[Pieter]

Be aware that the lens turret requires special boards for some lenses if you want the turret to rotate.

I have been told that it is difficult to keep critical alignment when using the turret. If you don't absolutely need it, you might consider converting it back to single-lens. The single lens boards are pretty easy to swap out, but I don't know what is involved in changing out the turret.

[Bob Salomon]

I have been told that it is difficult to keep critical alignment when using the turret. If you don't absolutely need it, you might consider converting it back to single-lens. The single lens boards are pretty easy to swap out, but I don't know what is involved in changing out the turret.

You are correct!

[Fred L]

I have been told that it is difficult to keep critical alignment when using the turret. If you don't absolutely need it, you might consider converting it back to single-lens. The single lens boards are pretty easy to swap out, but I don't know what is involved in changing out the turret.

triple lens turret is pulled out same as single boards. grip the tab and pull. undo bolts that secure lens boards and swap onto another board.

[ic-racer]

As long as the 80mm (shortest one on the turret in my case) is aligned, the lower magnification of the longer lenses on the turret allow for enough leeway in their alignment to still make perfect prints. I do mount the 50mm and shorter lenses separate and shim thier mounting plates so I don't have to re-do the enlarger's alignment when switching between the shorter lenses and the turret.

[Mark Sampson]

We had numerous turret-mounted Super-Chromegas at (that big photo company) and never saw an alignment problem due to the turrets. D5XLs or D6s, I'm not sure now.
Chromegatrols blowing up was the most common problem, followed by misaligned color heads (due to the offset weight in the dichroic heads). That was an easy fix, though.
IIRC they had equipped the turrets with 63/2.8 EL-Nikkors to get around the back-focus issues. It's been ten years since they dismantled all that, though, (and we seldom enlarged from small formats) so I'm going from memory on that one.

[ic-racer]

As magnification increases, the tolerance at the film plane decreases. I do enlarge Minox to 16x20 inches with my Omega D. The negative needs to be between glass and perfectly centered over the lens and the lens aligned to the glass with sub-millimeter precision. Pretty much to the same tolerance they use when manufacturing the Minox camera!

Going the other way, I have tested a 150mm lens with a 2x enlargement of 4x5 film (8x10" print) and the alignment can be off as much as 2 millimeters with no loss of sharpness I could detect in the print corners at f16 though it did show with the grain magnifier on the projected image.