Clark Objective



 
 
The objective is an air spaced achromatic doublet consisting of a bi-convex crown glass lens in front of a plano-concave flint lens. The lens diameter measures 9 - 1/4 inches, with a clear aperature of 9". The focal length is 108". 
Edge view of the objective removed from the cell. The lens and lens cell have no serial numbers or marks other than ones used for alignment. 
Edge detail of the inside of the brass lens cell.
The spacing of the two lens elements is accomplished by three strips of paper spaced 120 degrees apart, one of which can be seen in this photo.

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