Ian (127), interesting results. Thanks for putting the test and article together. It should be helpful in both a general sense (e.g. pointing out the need to make test prints) and to potential buyers of used enlarging lenses.

While you were careful to point out the parameters of your testing, and avoid any temptation to draw (or even suggest) conclusions beyond the scope of the tests, it may be helpful to point out a couple of additional caveats:

1. It's unclear whether these lenses were of the same or similar generations (dates of design and manufacture), or whether they were equivalent offerings (quality-wise) between the different manufacturers.

The Schneider Componar, for example, is old enough not to show up on the Schneider Vintage Lens Data page. If memory serves me, the Componar was an entry-level series dating from the mid '60s, with perhaps an even earlier design. I believe the Componar was replaced at the entry level by the Comparon, with the "better" grade in that generation being the early Componons. The Componons have since been replaced by the Componon-S, with the top-of-the-line APO Componon HM lenses being added more recently still.

2. Several of the usual control factors one might use in doing comparison tests are eliminated by the fact that these are used lenses. As such, there is no way to know how previous owners might have treated them, and any lack of care would likely impact the current capability of the individual lenses.