No. Focus with Aldis Back Lens Canera Extension at Infinity Plate covered sharply at full aperture Comments Source
Duo Trio Duo Trio Duo Trio
  Ins, Ins. Ins. Ins. Ins. Ins.
1 10   10 1/4   8 x 5   20
2 11 1/2 8 3/4 11 1/2 8 8 1/2 x 6 1/2 6 1/2 x 4 3/4 20
2a 12 3/4 9 3/4 12 1/4 8 3/4 10 x 8 7 x 5 For Series II to from F/12 with Duo and F/9 with Trio 20
3 14 1/2 11 14 1/2 10 11 x 9 8 1/2 x 6 1/2 20
4 17    13 17 12 12 x 10 10 x 8 20
             
6   9   8 1/2   6 1/2 x 4 3/4 20
6a   10   9 1/2   8 1/2 x 6 1/2 20
7 15 11 1/2 15 1/2 10 1/2 12 x 10 9 x 7 For Series III to form F/16.5 with Duo and F/11 with Trio 20
8 18   18 1/2   13 x 11   20
9 22   23   17 x 13   20