Exactly correct.
This let's me recommend one of the best things I think Aperture user's can do for themselves: set up one of the List views as a spreadsheet of all metadata (all that you can). The application of this to your question will be apparent.
What I recommend is added every single available metadata field to the List View -- Expanded Metadata Overlay.
"{Control}+j" will bring up the "Browser & Viewer Metadata" dialog. Select "List -- Expanded" from the View dropdown. Add _every_ field listed in the left column. Click "OK".
Now any time you change to List view ("{Control}+l" on my machine -- I don't think I customized this one), expanded view ("{Shift}+u" toggled between "Basic" and "Expanded" -- same as in the Browser) you will see, in spreadsheet form, a column for each metadata field that Aperture allows you to see. Scroll over to the column headed "Lens" and see how your lenses are named in the EXIF. Note that you can resize and move columns, and you can sort rows by any column (click the header, click again to reverse).
Most of my lenses are named. Cameras with fixed lenses frequently do not supply a lens name in the EXIF. Note, too, that the same lens may be listed differently by different cameras. Using the three metadata fields "Lens", "Camera Make", and "Camera Model" I can usually get the results I need.