Dallmeyer 3A / 3D

[lallan]

What is the difference between a Dallmeyer 3A and a Dallmeyer 3D lens? I have done some web searching and all I was able to come up with is both are modifications of a Petzval design.

Thanks,

....lyle

 

[smieglitz]

From an old Anthony catalog the 3A was "of ordinary intensity or rapidity" with 12" rear focus for full-plate.

The 3D had a smaller rear focus of 10.5" and was designated for either groups on full-plate or views on 8x10 being "entirely free from distortion and flare." Presumably this meant the 3A was faster and less corrected for spherical abberations, i.e., it gave rounder or more 3-dimensional looks to the portraits. I suspect the 3A was around f/3.8 (but listed as 12" focus & 4" element diameter) and the 3D around f/5 (10.5" focus & 2.125" diameter). The Lens Collector's Vade Mecum echoes those figures.

Joe