A.K.A. Single View Lens.
I think these were the basic option.
A diaphragm in front of a single cell of 2 or 3 cemented components which have the concave surface towards the diaphragm.
Less astigmatism & field curvature than the Petzval. The problems being a max aperture of f11 and barrel distortion in the outer field.
Anybody used one of these ancient optics? They were still being offered by Beck in 1903 as seperate lenses as well as the cheap option in their "Frena" range of cameras.
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