Special Hand Made Speed Lens-board

by Jo Lommen.

Some of my Large Format friends, had some serious doubts about the stability and light proof of the single lens board I made for my Aero experiment. Well, to be frank, I must say it crossed my mind, that under certain circumstances the lens board, not holding  the weight of the huge Aero Lens would bend a bit and give way to incoming light.  So it is obvious I had to find a solution for that. I already made a double lens board for the Aldis lens, but as the Aero lens has such a great diameter, there is not much space around on the board itself. On the other hand the second board will give a lot more stability to the lens board. So I decided to start building a prototype double lens board especially made for the Aero Lens.

Hand crafted precision:

The lower lens-board, must fit exactly into the square light trap of the front standard and the upper lens-board must fit precisely into the standard frame, thus creating an absolute reliable light-trap. 

Apart from the magnificent timeless design of brushed aluminum and the modern hex screws, these two boards built together, make one 2 mm strong lens-board, strong enough to resist the huge weight of the Aero lens. It has to hold for years and years under rude conditions. 

Consequence is that  the retaining ring, which must find its place between the lower (a) square and the lower (small) lens board, lying on the low rim (b) , has to  sacrifice 1 mm of its thickness, as there is no more space between a and b than just 4 mm. Not too much for a retainer with a diameter of 85 mm!

Front and rear board brought together in a

Double light-trap board hold together by hex screws. Rear and front board fitting exactly into the square standard.

a=lower light trap: b= low rim on which rest the rear board: c= high rim on which rest the front board: d=inner standard